| Message ID | 1487190207-5025-1-git-send-email-adhemerval.zanella@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
Ping. On 15/02/2017 21:23, Adhemerval Zanella wrote: > This is an update patch from my previous version (v3) based mainly on > glibc comments on exported loader symbol [1]. The changes from previous > version are: > > - Remove __tcb_private_ss call on libgcc and emit a data usage on > glibc symbol when split-stack is used. This removes the runtime > errors when running on older glibc and instead make the loader > fails with a missing symbol. > > - Add glibc version check on split-stack support check. > > - Some comments fixes on morestack.S. > > - Remove some compile warnings on morestack-c.c. > > -- > > This patch adds the split-stack support on aarch64 (PR #67877). As for > other ports this patch should be used along with glibc and gold support. > > The support is done similar to other architectures: a split-stack field > is allocated before TCB by glibc, a target-specific __morestack implementation > and helper functions are added in libgcc and compiler supported in adjusted > (split-stack prologue, va_start for argument handling). I also plan to > send the gold support to adjust stack allocation acrosss split-stack > and default code calls. > > Current approach is to set the final stack adjustments using a 2 instructions > at most (mov/movk) which limits stack allocation to upper limit of 4GB. > The morestack call is non standard with x10 hollding the requested stack > pointer, x11 the argument pointer (if required), and x12 to return > continuation address. Unwinding is handled by a personality routine that > knows how to find stack segments. > > Split-stack prologue on function entry is as follow (this goes before the > usual function prologue): > > function: > mrs x9, tpidr_el0 > mov x10, <required stack allocation> > movk x10, #0x0, lsl #16 > sub x10, sp, x10 > mov x11, sp # if function has stacked arguments > adrp x12, main_fn_entry > add x12, x12, :lo12:.L2 > cmp x9, x10 > b.lt <main_fn_entry> > b __morestack > main_fn_entry: > [function prologue] > > Notes: > > 1. Even if a function does not allocate a stack frame, a split-stack prologue > is created. It is to avoid issues with tail call for external symbols > which might require linker adjustment (libgo/runtime/go-varargs.c). > > 2. Basic-block reordering (enabled with -O2) will move split-stack TCB ldr > to after the required stack calculation. > > 3. Similar to powerpc, When the linker detects a call from split-stack to > non-split-stack code, it adds 16k (or more) to the value found in "allocate" > instructions (so non-split-stack code gets a larger stack). The amount is > tunable by a linker option. The edit means aarch64 does not need to > implement __morestack_non_split, necessary on x86 because insufficient > space is available there to edit the stack comparison code. This feature > is only implemented in the GNU gold linker. > > 4. AArch64 does not handle >4G stack initially and although it is possible > to implement it, limiting to 4G allows to materize the allocation with > only 2 instructions (mov + movk) and thus simplifying the linker > adjustments required. Supporting multiple threads each requiring more > than 4G of stack is probably not that important, and likely to OOM at > run time. > > 5. The TCB support on GLIBC is meant to be included in version 2.26. > > 6. The continuation address materialized on x12 is done using 'adrp' > plus add and a static relocation. Current code uses the > aarch64_expand_mov_immediate function and since a better alternative > would be 'adp', it could be a future optimization (not implemented > in this patch). > > [1] https://sourceware.org/ml/libc-alpha/2017-02/msg00272.html > > libgcc/ChangeLog: > > * libgcc/config.host: Use t-stack and t-statck-aarch64 for > aarch64*-*-linux. > * libgcc/config/aarch64/morestack-c.c: New file. > * libgcc/config/aarch64/morestack.S: Likewise. > * libgcc/config/aarch64/t-stack-aarch64: Likewise. > * libgcc/generic-morestack.c (__splitstack_find): Add aarch64-specific > code. > > gcc/ChangeLog: > > * common/config/aarch64/aarch64-common.c > (aarch64_supports_split_stack): New function. > (TARGET_SUPPORTS_SPLIT_STACK): New macro. > * gcc/config/aarch64/aarch64-linux.h (TARGET_ASM_FILE_END): Remove > macro. > * gcc/config/aarch64/aarch64-protos.h: Add > aarch64_expand_split_stack_prologue and > aarch64_split_stack_space_check. > * gcc/config/aarch64/aarch64.c (aarch64_gen_far_branch): Add suport > to emit 'b' instruction to rtx different than LABEL_REF. > (aarch64_expand_builtin_va_start): Use internal argument pointer > instead of virtual_incoming_args_rtx. > (morestack_ref): New symbol. > (aarch64_load_split_stack_value): New function. > (aarch64_expand_split_stack_prologue): Likewise. > (aarch64_internal_arg_pointer): Likewise. > (aarch64_split_stack_space_check): Likewise. > (aarch64_file_end): Emit the split-stack note sections. > (TARGET_ASM_FILE_END): New macro. > (TARGET_INTERNAL_ARG_POINTER): Likewise. > * gcc/config/aarch64/aarch64.h (aarch64_frame): Add > split_stack_arg_pointer to setup the argument pointer when using > split-stack. > * gcc/config/aarch64/aarch64.md > (UNSPECV_SPLIT_STACK_RETURN): Likewise. > (split_stack_prologue): New expand. > (split_stack_space_check): Likewise. > (split_stack_cond_call): Likewise. > --- > gcc/common/config/aarch64/aarch64-common.c | 31 +++- > gcc/config/aarch64/aarch64-linux.h | 2 - > gcc/config/aarch64/aarch64-protos.h | 2 + > gcc/config/aarch64/aarch64.c | 176 ++++++++++++++++++++- > gcc/config/aarch64/aarch64.h | 3 + > gcc/config/aarch64/aarch64.md | 56 +++++++ > libgcc/config.host | 1 + > libgcc/config/aarch64/morestack-c.c | 85 ++++++++++ > libgcc/config/aarch64/morestack.S | 246 +++++++++++++++++++++++++++++ > libgcc/config/aarch64/t-stack-aarch64 | 3 + > libgcc/generic-morestack.c | 1 + > 11 files changed, 601 insertions(+), 5 deletions(-) > create mode 100644 libgcc/config/aarch64/morestack-c.c > create mode 100644 libgcc/config/aarch64/morestack.S > create mode 100644 libgcc/config/aarch64/t-stack-aarch64 > > diff --git a/gcc/common/config/aarch64/aarch64-common.c b/gcc/common/config/aarch64/aarch64-common.c > index a0b7f48..05fe4e4 100644 > --- a/gcc/common/config/aarch64/aarch64-common.c > +++ b/gcc/common/config/aarch64/aarch64-common.c > @@ -107,6 +107,36 @@ aarch64_handle_option (struct gcc_options *opts, > } > } > > +/* -fsplit-stack uses an area allocated before thread pointer (which points > + to TCB) and it is available on glibc-2.26. GLIBC also exports a symbol > + (__libc_tcb_private_ss) to signal it allocates the pre-TCB area. > + This aims to prevent binaries linked against newer GLIBC to run on > + non-supported ones. */ > + > +static bool > +aarch64_supports_split_stack (bool report ATTRIBUTE_UNUSED, > + struct gcc_options *opts ATTRIBUTE_UNUSED) > +{ > +#ifndef TARGET_GLIBC_MAJOR > +#define TARGET_GLIBC_MAJOR 0 > +#endif > +#ifndef TARGET_GLIBC_MINOR > +#define TARGET_GLIBC_MINOR 0 > +#endif > + > + /* Note: Can't test DEFAULT_ABI here, it isn't set until later. */ > + if (TARGET_GLIBC_MAJOR * 1000 + TARGET_GLIBC_MINOR >= 2026) > + return true; > + > + if (report) > + error ("%<-fsplit-stack%> currently only supported on AArch64 GNU/Linux" > + " with glibc-2.26 or later"); > + return false; > +} > + > +#undef TARGET_SUPPORTS_SPLIT_STACK > +#define TARGET_SUPPORTS_SPLIT_STACK aarch64_supports_split_stack > + > struct gcc_targetm_common targetm_common = TARGETM_COMMON_INITIALIZER; > > /* An ISA extension in the co-processor and main instruction set space. */ > @@ -340,4 +370,3 @@ aarch64_rewrite_mcpu (int argc, const char **argv) > } > > #undef AARCH64_CPU_NAME_LENGTH > - > diff --git a/gcc/config/aarch64/aarch64-linux.h b/gcc/config/aarch64/aarch64-linux.h > index c45fc1d..b8daba4 100644 > --- a/gcc/config/aarch64/aarch64-linux.h > +++ b/gcc/config/aarch64/aarch64-linux.h > @@ -80,8 +80,6 @@ > } \ > while (0) > > -#define TARGET_ASM_FILE_END file_end_indicate_exec_stack > - > /* Uninitialized common symbols in non-PIE executables, even with > strong definitions in dependent shared libraries, will resolve > to COPY relocated symbol in the executable. See PR65780. */ > diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h > index 9543f8c..5766afd 100644 > --- a/gcc/config/aarch64/aarch64-protos.h > +++ b/gcc/config/aarch64/aarch64-protos.h > @@ -383,6 +383,8 @@ void aarch64_err_no_fpadvsimd (machine_mode, const char *); > void aarch64_expand_epilogue (bool); > void aarch64_expand_mov_immediate (rtx, rtx); > void aarch64_expand_prologue (void); > +void aarch64_expand_split_stack_prologue (void); > +void aarch64_split_stack_space_check (rtx, rtx); > void aarch64_expand_vector_init (rtx, rtx); > void aarch64_init_cumulative_args (CUMULATIVE_ARGS *, const_tree, rtx, > const_tree, unsigned); > diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c > index 4be3131..c21116a 100644 > --- a/gcc/config/aarch64/aarch64.c > +++ b/gcc/config/aarch64/aarch64.c > @@ -913,7 +913,12 @@ aarch64_gen_far_branch (rtx * operands, int pos_label, const char * dest, > snprintf (buffer, sizeof (buffer), "%s%s", branch_format, label_ptr); > output_asm_insn (buffer, operands); > > - snprintf (buffer, sizeof (buffer), "b\t%%l%d\n%s:", pos_label, label_ptr); > + if (GET_CODE (operands[pos_label]) == LABEL_REF) > + snprintf (buffer, sizeof (buffer), "b\t%%l%d\n%s:", pos_label, > + label_ptr); > + else > + snprintf (buffer, sizeof (buffer), "b\t%%%d\n%s:", pos_label, > + label_ptr); > operands[pos_label] = dest_label; > output_asm_insn (buffer, operands); > return ""; > @@ -10139,7 +10144,7 @@ aarch64_expand_builtin_va_start (tree valist, rtx nextarg ATTRIBUTE_UNUSED) > /* Emit code to initialize STACK, which points to the next varargs stack > argument. CUM->AAPCS_STACK_SIZE gives the number of stack words used > by named arguments. STACK is 8-byte aligned. */ > - t = make_tree (TREE_TYPE (stack), virtual_incoming_args_rtx); > + t = make_tree (TREE_TYPE (stack), crtl->args.internal_arg_pointer); > if (cum->aapcs_stack_size > 0) > t = fold_build_pointer_plus_hwi (t, cum->aapcs_stack_size * UNITS_PER_WORD); > t = build2 (MODIFY_EXPR, TREE_TYPE (stack), stack, t); > @@ -14682,6 +14687,167 @@ aarch64_excess_precision (enum excess_precision_type type) > return FLT_EVAL_METHOD_UNPREDICTABLE; > } > > +/* -fsplit-stack support. */ > + > +/* A SYMBOL_REF for __morestack. */ > +static GTY(()) rtx morestack_ref; > + > +/* Load split-stack area from thread pointer position. The split-stack is > + allocate just before thread pointer. */ > + > +static rtx > +aarch64_load_split_stack_value (bool use_hard_reg) > +{ > + /* Offset from thread pointer to split-stack area. */ > + const int psso = -8; > + > + rtx ssvalue = use_hard_reg > + ? gen_rtx_REG (Pmode, R9_REGNUM) : gen_reg_rtx (Pmode); > + ssvalue = aarch64_load_tp (ssvalue); > + rtx mem = gen_rtx_MEM (Pmode, plus_constant (Pmode, ssvalue, psso)); > + emit_move_insn (ssvalue, mem); > + return ssvalue; > +} > + > +/* Emit -fsplit-stack prologue, which goes before the regular function > + prologue. */ > + > +void > +aarch64_expand_split_stack_prologue (void) > +{ > + rtx ssvalue, reg10, reg11, reg12, cc, cmp, jump; > + HOST_WIDE_INT allocate; > + rtx_code_label *ok_label = NULL; > + > + gcc_assert (flag_split_stack && reload_completed); > + > + /* It limits total maximum stack allocation on 4G so its value can be > + materialized using two instructions at most (movn/movk). It might be > + used by the linker to add some extra space for split calling non split > + stack functions. */ > + allocate = cfun->machine->frame.frame_size; > + if (allocate > ((int64_t)1 << 32)) > + { > + sorry ("Stack frame larger than 4G is not supported for -fsplit-stack"); > + return; > + } > + > + if (morestack_ref == NULL_RTX) > + { > + morestack_ref = gen_rtx_SYMBOL_REF (Pmode, "__morestack"); > + SYMBOL_REF_FLAGS (morestack_ref) |= (SYMBOL_FLAG_LOCAL > + | SYMBOL_FLAG_FUNCTION); > + } > + > + ssvalue = aarch64_load_split_stack_value (true); > + > + /* Always emit two insns to calculate the requested stack, so the linker > + can edit them when adjusting size for calling non-split-stack code. */ > + reg10 = gen_rtx_REG (Pmode, R10_REGNUM); > + emit_insn (gen_rtx_SET (reg10, GEN_INT (allocate & 0xffff))); > + emit_insn (gen_insv_immdi (reg10, GEN_INT (16), > + GEN_INT ((allocate & 0xffff0000) >> 16))); > + emit_insn (gen_sub3_insn (reg10, stack_pointer_rtx, reg10)); > + > + ok_label = gen_label_rtx (); > + > + /* If function uses stacked arguments save the old stack value so morestack > + can return it. */ > + reg11 = gen_rtx_REG (Pmode, R11_REGNUM); > + if (crtl->args.size > + || cfun->machine->frame.saved_varargs_size) > + emit_move_insn (reg11, stack_pointer_rtx); > + > + /* x12 holds the continuation address used to return to function. */ > + reg12 = gen_rtx_REG (Pmode, R12_REGNUM); > + aarch64_expand_mov_immediate (reg12, gen_rtx_LABEL_REF (VOIDmode, ok_label)); > + > + /* Jump to __morestack call if current ss guard is not suffice. */ > + cc = aarch64_gen_compare_reg (GE, ssvalue, reg10); > + cmp = gen_rtx_fmt_ee (GE, VOIDmode, cc, const0_rtx); > + jump = gen_split_stack_cond_call (morestack_ref, cmp, ok_label, reg12); > + > + aarch64_emit_unlikely_jump (jump); > + JUMP_LABEL (jump) = ok_label; > + LABEL_NUSES (ok_label)++; > + > + /* __morestack will call us here. */ > + emit_label (ok_label); > +} > + > +/* Implement TARGET_ASM_FILE_END. */ > + > +static void > +aarch64_file_end (void) > +{ > + file_end_indicate_exec_stack (); > + > + if (flag_split_stack) > + { > + file_end_indicate_split_stack (); > + > + /* Emit a reference to special symbol that LIBC uses to declare it > + supports the split-stack before TCB. */ > + switch_to_section (data_section); > + fprintf (asm_out_file, "\t.align 3\n"); > + fprintf (asm_out_file, "\t.quad __libc_tcb_private_ss\n"); > + } > +} > + > +/* Return the internal arg pointer used for function incoming arguments. */ > + > +static rtx > +aarch64_internal_arg_pointer (void) > +{ > + if (flag_split_stack > + && (lookup_attribute ("no_split_stack", DECL_ATTRIBUTES (cfun->decl)) > + == NULL)) > + { > + if (cfun->machine->frame.split_stack_arg_pointer == NULL_RTX) > + { > + rtx pat; > + > + cfun->machine->frame.split_stack_arg_pointer = gen_reg_rtx (Pmode); > + REG_POINTER (cfun->machine->frame.split_stack_arg_pointer) = 1; > + > + /* Put the pseudo initialization right after the note at the > + beginning of the function. */ > + pat = gen_rtx_SET (cfun->machine->frame.split_stack_arg_pointer, > + gen_rtx_REG (Pmode, R11_REGNUM)); > + push_topmost_sequence (); > + emit_insn_after (pat, get_insns ()); > + pop_topmost_sequence (); > + } > + return plus_constant (Pmode, cfun->machine->frame.split_stack_arg_pointer, > + FIRST_PARM_OFFSET (current_function_decl)); > + } > + return virtual_incoming_args_rtx; > +} > + > +/* Emit -fsplit-stack dynamic stack allocation space check. */ > + > +void > +aarch64_split_stack_space_check (rtx size, rtx label) > +{ > + rtx ssvalue, cc, cmp, jump, temp; > + rtx requested = gen_reg_rtx (Pmode); > + > + /* Load __private_ss from TCB. */ > + ssvalue = aarch64_load_split_stack_value (false); > + > + temp = gen_reg_rtx (Pmode); > + > + /* And compare it with frame pointer plus required stack. */ > + size = force_reg (Pmode, size); > + emit_move_insn (requested, gen_rtx_MINUS (Pmode, stack_pointer_rtx, size)); > + > + /* Jump to label call if current ss guard is not suffice. */ > + cc = aarch64_gen_compare_reg (LT, temp, ssvalue); > + cmp = gen_rtx_fmt_ee (GEU, VOIDmode, cc, const0_rtx); > + jump = emit_jump_insn (gen_condjump (cmp, cc, label)); > + JUMP_LABEL (jump) = label; > +} > + > /* Target-specific selftests. */ > > #if CHECKING_P > @@ -14754,6 +14920,9 @@ aarch64_run_selftests (void) > #undef TARGET_ASM_FILE_START > #define TARGET_ASM_FILE_START aarch64_start_file > > +#undef TARGET_ASM_FILE_END > +#define TARGET_ASM_FILE_END aarch64_file_end > + > #undef TARGET_ASM_OUTPUT_MI_THUNK > #define TARGET_ASM_OUTPUT_MI_THUNK aarch64_output_mi_thunk > > @@ -14839,6 +15008,9 @@ aarch64_run_selftests (void) > #undef TARGET_FRAME_POINTER_REQUIRED > #define TARGET_FRAME_POINTER_REQUIRED aarch64_frame_pointer_required > > +#undef TARGET_INTERNAL_ARG_POINTER > +#define TARGET_INTERNAL_ARG_POINTER aarch64_internal_arg_pointer > + > #undef TARGET_GIMPLE_FOLD_BUILTIN > #define TARGET_GIMPLE_FOLD_BUILTIN aarch64_gimple_fold_builtin > > diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h > index e4fb96f..510f60a 100644 > --- a/gcc/config/aarch64/aarch64.h > +++ b/gcc/config/aarch64/aarch64.h > @@ -594,6 +594,9 @@ struct GTY (()) aarch64_frame > unsigned wb_candidate2; > > bool laid_out; > + > + /* Alternative internal arg pointer for -fsplit-stack. */ > + rtx split_stack_arg_pointer; > }; > > typedef struct GTY (()) machine_function > diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md > index 5adc5ed..b0141f9 100644 > --- a/gcc/config/aarch64/aarch64.md > +++ b/gcc/config/aarch64/aarch64.md > @@ -150,6 +150,7 @@ > UNSPECV_SET_FPSR ; Represent assign of FPSR content. > UNSPECV_BLOCKAGE ; Represent a blockage > UNSPECV_PROBE_STACK_RANGE ; Represent stack range probing. > + UNSPECV_SPLIT_STACK_CALL ; Represent a morestack call > ] > ) > > @@ -5572,3 +5573,58 @@ > > ;; ldp/stp peephole patterns > (include "aarch64-ldpstp.md") > + > +;; Handle -fsplit-stack > +(define_expand "split_stack_prologue" > + [(const_int 0)] > + "" > +{ > + aarch64_expand_split_stack_prologue (); > + DONE; > +}) > + > +;; If there are operand 0 bytes available on the stack, jump to > +;; operand 1. > +(define_expand "split_stack_space_check" > + [(set (match_dup 2) (compare:CC (match_dup 3) (match_dup 2))) > + (set (pc) (if_then_else > + (geu (match_dup 4) (const_int 0)) > + (label_ref (match_operand 1)) > + (pc)))] > + "" > +{ > + aarch64_split_stack_space_check (operands[0], operands[1]); > + DONE; > +}) > + > +;; A __morestack call using branch > + > +(define_expand "split_stack_cond_call" > + [(match_operand 0 "aarch64_call_insn_operand" "") > + (match_operand 1 "" "") > + (match_operand 2 "" "") > + (match_operand 3 "" "")] > + "" > +{ > + emit_jump_insn (gen_split_stack_cond_call_di (operands[0], operands[1], > + operands[2], operands[3])); > + DONE; > +}) > + > + > +(define_insn "split_stack_cond_call_<mode>" > + [(set (pc) > + (if_then_else > + (match_operand 1 "aarch64_comparison_operator" "") > + (label_ref (match_operand 2 "" "")) > + (pc))) > + (set (reg:P 1) (unspec_volatile:P [(match_operand:P 0 "aarch64_call_insn_operand" "") > + (reg:P 1)] > + UNSPECV_SPLIT_STACK_CALL)) > + (use (match_operand:P 3 "register_operand" ""))] > + "" > + { > + return aarch64_gen_far_branch (operands, 0, "Lbcond", "b%M1\\t"); > + } > + [(set_attr "type" "branch")] > +) > diff --git a/libgcc/config.host b/libgcc/config.host > index 9472a60..d6f4312 100644 > --- a/libgcc/config.host > +++ b/libgcc/config.host > @@ -347,6 +347,7 @@ aarch64*-*-linux*) > md_unwind_header=aarch64/linux-unwind.h > tmake_file="${tmake_file} ${cpu_type}/t-aarch64" > tmake_file="${tmake_file} ${cpu_type}/t-softfp t-softfp t-crtfm" > + tmake_file="${tmake_file} t-stack aarch64/t-stack-aarch64" > ;; > alpha*-*-linux*) > tmake_file="${tmake_file} alpha/t-alpha alpha/t-ieee t-crtfm alpha/t-linux" > diff --git a/libgcc/config/aarch64/morestack-c.c b/libgcc/config/aarch64/morestack-c.c > new file mode 100644 > index 0000000..607ef05 > --- /dev/null > +++ b/libgcc/config/aarch64/morestack-c.c > @@ -0,0 +1,85 @@ > +/* AArch64 support for -fsplit-stack. > + * Copyright (C) 2016 Free Software Foundation, Inc. > + * > + * This file is free software; you can redistribute it and/or modify it > + * under the terms of the GNU General Public License as published by the > + * Free Software Foundation; either version 3, or (at your option) any > + * later version. > + * > + * This file is distributed in the hope that it will be useful, but > + * WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + * General Public License for more details. > + * > + * Under Section 7 of GPL version 3, you are granted additional > + * permissions described in the GCC Runtime Library Exception, version > + * 3.1, as published by the Free Software Foundation. > + * > + * You should have received a copy of the GNU General Public License and > + * a copy of the GCC Runtime Library Exception along with this program; > + * see the files COPYING3 and COPYING.RUNTIME respectively. If not, see > + * <http://www.gnu.org/licenses/>. > + */ > + > +#ifndef inhibit_libc > + > +#include <stdint.h> > +#include <stdlib.h> > +#include <stddef.h> > +#include "generic-morestack.h" > + > +#define INITIAL_STACK_SIZE 0x4000 > +#define BACKOFF 0x1000 > + > +void __generic_morestack_set_initial_sp (void *sp, size_t len); > +void *__morestack_get_guard (void); > +void __morestack_set_guard (void *); > +void *__morestack_make_guard (void *stack, size_t size); > +void __morestack_load_mmap (void); > + > +/* split-stack area position from thread pointer. */ > +#define SPLITSTACK_PTR_TP (-8) > + > +/* Initialize the stack guard when the program starts or when a new > + thread. This is called from a constructor using ctors section. */ > +void > +__stack_split_initialize (void) > +{ > + register uintptr_t* sp __asm__ ("sp"); > + uintptr_t *ss = (uintptr_t*)((char*)__builtin_thread_pointer () > + + SPLITSTACK_PTR_TP); > + *ss = (uintptr_t)sp - INITIAL_STACK_SIZE; > + __generic_morestack_set_initial_sp (sp, INITIAL_STACK_SIZE); > +} > + > +/* Return current __private_ss. */ > +void * > +__morestack_get_guard (void) > +{ > + void **ss = (void**)((char*)__builtin_thread_pointer () > + + SPLITSTACK_PTR_TP); > + return *ss; > +} > + > +/* Set __private_ss to ptr. */ > +void > +__morestack_set_guard (void *ptr) > +{ > + void **ss = (void**)((char*)__builtin_thread_pointer () > + + SPLITSTACK_PTR_TP); > + *ss = ptr; > +} > + > +/* Return the stack guard value for given stack. */ > +void * > +__morestack_make_guard (void *stack, size_t size) > +{ > + return (void*)((uintptr_t)stack - size + BACKOFF); > +} > + > +/* Make __stack_split_initialize a high priority constructor. */ > +static void (*const ctors []) > + __attribute__ ((used, section (".ctors.65535"), aligned (sizeof (void *)))) > + = { __stack_split_initialize, __morestack_load_mmap }; > + > +#endif /* !defined (inhibit_libc) */ > diff --git a/libgcc/config/aarch64/morestack.S b/libgcc/config/aarch64/morestack.S > new file mode 100644 > index 0000000..c8a3d82 > --- /dev/null > +++ b/libgcc/config/aarch64/morestack.S > @@ -0,0 +1,246 @@ > +# AArch64 support for -fsplit-stack. > +# Copyright (C) 2016 Free Software Foundation, Inc. > + > +# This file is part of GCC. > + > +# GCC is free software; you can redistribute it and/or modify it under > +# the terms of the GNU General Public License as published by the Free > +# Software Foundation; either version 3, or (at your option) any later > +# version. > + > +# GCC is distributed in the hope that it will be useful, but WITHOUT ANY > +# WARRANTY; without even the implied warranty of MERCHANTABILITY or > +# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License > +# for more details. > + > +# Under Section 7 of GPL version 3, you are granted additional > +# permissions described in the GCC Runtime Library Exception, version > +# 3.1, as published by the Free Software Foundation. > + > +# You should have received a copy of the GNU General Public License and > +# a copy of the GCC Runtime Library Exception along with this program; > +# see the files COPYING3 and COPYING.RUNTIME respectively. If not, see > +# <http://www.gnu.org/licenses/>. > + > +/* Define an entry point visible from C. */ > +#define ENTRY(name) \ > + .globl name; \ > + .type name,%function; \ > + .align 4; \ > + name##: > + > +#define END(name) \ > + .size name,.-name > + > +/* __morestack frame size. */ > +#define MORESTACK_FRAMESIZE 112 > +/* Offset from __morestack frame where the new stack size is saved and > + passed to __generic_morestack. */ > +#define NEWSTACK_SAVE 96 > + > +#define BACKOFF 0x1000 > +# Large excess allocated when calling non-split-stack code. > +#define NON_SPLIT_STACK 0x100000 > + > +/* split-stack area position from thread pointer. */ > +#define SPLITSTACK_PTR_TP -8 > + > + .text > +ENTRY(__morestack_non_split) > + .cfi_startproc > +# We use a cleanup to restore the tcbhead_t.__private_ss if > +# an exception is thrown through this code. > + add x10, x10, NON_SPLIT_STACK > + .cfi_endproc > +END(__morestack_non_split) > +# Fall through into __morestack > + > +# This function is called with non-standard calling conventions, on entry > +# x10 is the requested stack pointer. The split-stack prologue is in the > +# form: > +# > +# function: > +# mrs x9, tpidr_el0 > +# mov x10, <required stack allocation> > +# movk x10, #0x0, lsl #16 > +# sub x10, sp, x10 > +# mov x11, sp # if function has stacked arguments > +# adrp x12, main_fn_entry > +# add x12, x12, :lo12:.L2 > +# cmp x9, x10 > +# b.lt <main_fn_entry> > +# b __morestack > +# main_fn_entry: > +# [function prologue] > +# > +# The N bit is also restored to indicate that the function is called > +# (so the prologue addition can set up the argument pointer correctly). > + > +ENTRY(__morestack) > +.LFB1: > + .cfi_startproc > + > +#ifdef __PIC__ > + .cfi_personality 0x9b,DW.ref.__gcc_personality_v0 > + .cfi_lsda 0x1b,.LLSDA1 > +#else > + .cfi_personality 0x3,__gcc_personality_v0 > + .cfi_lsda 0x3,.LLSDA1 > +#endif > + > + # Calculate requested stack size. > + sub x10, sp, x10 > + # Save parameters > + stp x29, x30, [sp, -MORESTACK_FRAMESIZE]! > + .cfi_def_cfa_offset MORESTACK_FRAMESIZE > + .cfi_offset 29, -MORESTACK_FRAMESIZE > + .cfi_offset 30, -MORESTACK_FRAMESIZE+8 > + add x29, sp, 0 > + .cfi_def_cfa_register 29 > + # Adjust the requested stack size for the frame pointer save. > + stp x0, x1, [sp, 16] > + stp x2, x3, [sp, 32] > + add x10, x10, BACKOFF > + stp x4, x5, [sp, 48] > + stp x6, x7, [sp, 64] > + stp x8, x12, [sp, 80] > + str x10, [sp, 96] > + > + # void __morestack_block_signals (void) > + bl __morestack_block_signals > + > + # void *__generic_morestack (size_t *pframe_size, > + # void *old_stack, > + # size_t param_size) > + # pframe_size: is the size of the required stack frame (the function > + # amount of space remaining on the allocated stack). > + # old_stack: points at the parameters the old stack > + # param_size: size in bytes of parameters to copy to the new stack. > + add x0, x29, NEWSTACK_SAVE > + add x1, x29, MORESTACK_FRAMESIZE > + mov x2, 0 > + bl __generic_morestack > + > + # Start using new stack > + mov sp, x0 > + > + # Set __private_ss stack guard for the new stack. > + ldr x9, [x29, NEWSTACK_SAVE] > + add x0, x0, BACKOFF > + sub x0, x0, x9 > +.LEHB0: > + mrs x1, tpidr_el0 > + str x0, [x1, SPLITSTACK_PTR_TP] > + > + # void __morestack_unblock_signals (void) > + bl __morestack_unblock_signals > + > + # Set up for a call to the target function. > + ldp x0, x1, [x29, 16] > + ldp x2, x3, [x29, 32] > + ldp x4, x5, [x29, 48] > + ldp x6, x7, [x29, 64] > + ldp x8, x12, [x29, 80] > + add x11, x29, MORESTACK_FRAMESIZE > + # Indicate __morestack was called. > + cmp x12, 0 > + blr x12 > + > + stp x0, x1, [x29, 16] > + stp x2, x3, [x29, 32] > + stp x4, x5, [x29, 48] > + stp x6, x7, [x29, 64] > + > + bl __morestack_block_signals > + > + # void *__generic_releasestack (size_t *pavailable) > + add x0, x29, NEWSTACK_SAVE > + bl __generic_releasestack > + > + # Reset __private_ss stack guard to value for old stack > + ldr x9, [x29, NEWSTACK_SAVE] > + add x0, x0, BACKOFF > + sub x0, x0, x9 > + > + # Update TCB split stack field > +.LEHE0: > + mrs x1, tpidr_el0 > + str x0, [x1, SPLITSTACK_PTR_TP] > + > + bl __morestack_unblock_signals > + > + # Use old stack again. > + add sp, x29, MORESTACK_FRAMESIZE > + > + ldp x0, x1, [x29, 16] > + ldp x2, x3, [x29, 32] > + ldp x4, x5, [x29, 48] > + ldp x6, x7, [x29, 64] > + ldp x29, x30, [x29] > + > + .cfi_remember_state > + .cfi_restore 30 > + .cfi_restore 29 > + .cfi_def_cfa 31, 0 > + > + ret > + > +# This is the cleanup code called by the stack unwinder when > +# unwinding through code between .LEHB0 and .LEHE0 above. > +cleanup: > + .cfi_restore_state > + # Reuse the new stack allocation to save/restore the > + # exception header > + str x0, [x29, NEWSTACK_SAVE] > + # size_t __generic_findstack (void *stack) > + add x0, x29, MORESTACK_FRAMESIZE > + bl __generic_findstack > + sub x0, x29, x0 > + add x0, x0, BACKOFF > + # Restore split-stack guard value > + mrs x1, tpidr_el0 > + str x0, [x1, SPLITSTACK_PTR_TP] > + ldr x0, [x29, NEWSTACK_SAVE] > + b _Unwind_Resume > + .cfi_endproc > +END(__morestack) > + > + .section .gcc_except_table,"a",@progbits > + .align 4 > +.LLSDA1: > + # @LPStart format (omit) > + .byte 0xff > + # @TType format (omit) > + .byte 0xff > + # Call-site format (uleb128) > + .byte 0x1 > + # Call-site table length > + .uleb128 .LLSDACSE1-.LLSDACSB1 > +.LLSDACSB1: > + # region 0 start > + .uleb128 .LEHB0-.LFB1 > + # length > + .uleb128 .LEHE0-.LEHB0 > + # landing pad > + .uleb128 cleanup-.LFB1 > + # no action (ie a cleanup) > + .uleb128 0 > +.LLSDACSE1: > + > + > + .global __gcc_personality_v0 > +#ifdef __PIC__ > + # Build a position independent reference to the personality function. > + .hidden DW.ref.__gcc_personality_v0 > + .weak DW.ref.__gcc_personality_v0 > + .section .data.DW.ref.__gcc_personality_v0,"awG",@progbits,DW.ref.__gcc_personality_v0,comdat > + .type DW.ref.__gcc_personality_v0, @object > + .align 3 > +DW.ref.__gcc_personality_v0: > + .size DW.ref.__gcc_personality_v0, 8 > + .quad __gcc_personality_v0 > +#endif > + > + .section .note.GNU-stack,"",@progbits > + .section .note.GNU-split-stack,"",@progbits > + .section .note.GNU-no-split-stack,"",@progbits > diff --git a/libgcc/config/aarch64/t-stack-aarch64 b/libgcc/config/aarch64/t-stack-aarch64 > new file mode 100644 > index 0000000..4babb4e > --- /dev/null > +++ b/libgcc/config/aarch64/t-stack-aarch64 > @@ -0,0 +1,3 @@ > +# Makefile fragment to support -fsplit-stack for aarch64. > +LIB2ADD_ST += $(srcdir)/config/aarch64/morestack.S \ > + $(srcdir)/config/aarch64/morestack-c.c > diff --git a/libgcc/generic-morestack.c b/libgcc/generic-morestack.c > index adbe436..e91ceb4 100644 > --- a/libgcc/generic-morestack.c > +++ b/libgcc/generic-morestack.c > @@ -943,6 +943,7 @@ __splitstack_find (void *segment_arg, void *sp, size_t *len, > nsp -= 2 * 160; > #elif defined __s390__ > nsp -= 2 * 96; > +#elif defined __aarch64__ > #else > #error "unrecognized target" > #endif >
diff --git a/gcc/common/config/aarch64/aarch64-common.c b/gcc/common/config/aarch64/aarch64-common.c index a0b7f48..05fe4e4 100644 --- a/gcc/common/config/aarch64/aarch64-common.c +++ b/gcc/common/config/aarch64/aarch64-common.c @@ -107,6 +107,36 @@ aarch64_handle_option (struct gcc_options *opts, } } +/* -fsplit-stack uses an area allocated before thread pointer (which points + to TCB) and it is available on glibc-2.26. GLIBC also exports a symbol + (__libc_tcb_private_ss) to signal it allocates the pre-TCB area. + This aims to prevent binaries linked against newer GLIBC to run on + non-supported ones. */ + +static bool +aarch64_supports_split_stack (bool report ATTRIBUTE_UNUSED, + struct gcc_options *opts ATTRIBUTE_UNUSED) +{ +#ifndef TARGET_GLIBC_MAJOR +#define TARGET_GLIBC_MAJOR 0 +#endif +#ifndef TARGET_GLIBC_MINOR +#define TARGET_GLIBC_MINOR 0 +#endif + + /* Note: Can't test DEFAULT_ABI here, it isn't set until later. */ + if (TARGET_GLIBC_MAJOR * 1000 + TARGET_GLIBC_MINOR >= 2026) + return true; + + if (report) + error ("%<-fsplit-stack%> currently only supported on AArch64 GNU/Linux" + " with glibc-2.26 or later"); + return false; +} + +#undef TARGET_SUPPORTS_SPLIT_STACK +#define TARGET_SUPPORTS_SPLIT_STACK aarch64_supports_split_stack + struct gcc_targetm_common targetm_common = TARGETM_COMMON_INITIALIZER; /* An ISA extension in the co-processor and main instruction set space. */ @@ -340,4 +370,3 @@ aarch64_rewrite_mcpu (int argc, const char **argv) } #undef AARCH64_CPU_NAME_LENGTH - diff --git a/gcc/config/aarch64/aarch64-linux.h b/gcc/config/aarch64/aarch64-linux.h index c45fc1d..b8daba4 100644 --- a/gcc/config/aarch64/aarch64-linux.h +++ b/gcc/config/aarch64/aarch64-linux.h @@ -80,8 +80,6 @@ } \ while (0) -#define TARGET_ASM_FILE_END file_end_indicate_exec_stack - /* Uninitialized common symbols in non-PIE executables, even with strong definitions in dependent shared libraries, will resolve to COPY relocated symbol in the executable. See PR65780. */ diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h index 9543f8c..5766afd 100644 --- a/gcc/config/aarch64/aarch64-protos.h +++ b/gcc/config/aarch64/aarch64-protos.h @@ -383,6 +383,8 @@ void aarch64_err_no_fpadvsimd (machine_mode, const char *); void aarch64_expand_epilogue (bool); void aarch64_expand_mov_immediate (rtx, rtx); void aarch64_expand_prologue (void); +void aarch64_expand_split_stack_prologue (void); +void aarch64_split_stack_space_check (rtx, rtx); void aarch64_expand_vector_init (rtx, rtx); void aarch64_init_cumulative_args (CUMULATIVE_ARGS *, const_tree, rtx, const_tree, unsigned); diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c index 4be3131..c21116a 100644 --- a/gcc/config/aarch64/aarch64.c +++ b/gcc/config/aarch64/aarch64.c @@ -913,7 +913,12 @@ aarch64_gen_far_branch (rtx * operands, int pos_label, const char * dest, snprintf (buffer, sizeof (buffer), "%s%s", branch_format, label_ptr); output_asm_insn (buffer, operands); - snprintf (buffer, sizeof (buffer), "b\t%%l%d\n%s:", pos_label, label_ptr); + if (GET_CODE (operands[pos_label]) == LABEL_REF) + snprintf (buffer, sizeof (buffer), "b\t%%l%d\n%s:", pos_label, + label_ptr); + else + snprintf (buffer, sizeof (buffer), "b\t%%%d\n%s:", pos_label, + label_ptr); operands[pos_label] = dest_label; output_asm_insn (buffer, operands); return ""; @@ -10139,7 +10144,7 @@ aarch64_expand_builtin_va_start (tree valist, rtx nextarg ATTRIBUTE_UNUSED) /* Emit code to initialize STACK, which points to the next varargs stack argument. CUM->AAPCS_STACK_SIZE gives the number of stack words used by named arguments. STACK is 8-byte aligned. */ - t = make_tree (TREE_TYPE (stack), virtual_incoming_args_rtx); + t = make_tree (TREE_TYPE (stack), crtl->args.internal_arg_pointer); if (cum->aapcs_stack_size > 0) t = fold_build_pointer_plus_hwi (t, cum->aapcs_stack_size * UNITS_PER_WORD); t = build2 (MODIFY_EXPR, TREE_TYPE (stack), stack, t); @@ -14682,6 +14687,167 @@ aarch64_excess_precision (enum excess_precision_type type) return FLT_EVAL_METHOD_UNPREDICTABLE; } +/* -fsplit-stack support. */ + +/* A SYMBOL_REF for __morestack. */ +static GTY(()) rtx morestack_ref; + +/* Load split-stack area from thread pointer position. The split-stack is + allocate just before thread pointer. */ + +static rtx +aarch64_load_split_stack_value (bool use_hard_reg) +{ + /* Offset from thread pointer to split-stack area. */ + const int psso = -8; + + rtx ssvalue = use_hard_reg + ? gen_rtx_REG (Pmode, R9_REGNUM) : gen_reg_rtx (Pmode); + ssvalue = aarch64_load_tp (ssvalue); + rtx mem = gen_rtx_MEM (Pmode, plus_constant (Pmode, ssvalue, psso)); + emit_move_insn (ssvalue, mem); + return ssvalue; +} + +/* Emit -fsplit-stack prologue, which goes before the regular function + prologue. */ + +void +aarch64_expand_split_stack_prologue (void) +{ + rtx ssvalue, reg10, reg11, reg12, cc, cmp, jump; + HOST_WIDE_INT allocate; + rtx_code_label *ok_label = NULL; + + gcc_assert (flag_split_stack && reload_completed); + + /* It limits total maximum stack allocation on 4G so its value can be + materialized using two instructions at most (movn/movk). It might be + used by the linker to add some extra space for split calling non split + stack functions. */ + allocate = cfun->machine->frame.frame_size; + if (allocate > ((int64_t)1 << 32)) + { + sorry ("Stack frame larger than 4G is not supported for -fsplit-stack"); + return; + } + + if (morestack_ref == NULL_RTX) + { + morestack_ref = gen_rtx_SYMBOL_REF (Pmode, "__morestack"); + SYMBOL_REF_FLAGS (morestack_ref) |= (SYMBOL_FLAG_LOCAL + | SYMBOL_FLAG_FUNCTION); + } + + ssvalue = aarch64_load_split_stack_value (true); + + /* Always emit two insns to calculate the requested stack, so the linker + can edit them when adjusting size for calling non-split-stack code. */ + reg10 = gen_rtx_REG (Pmode, R10_REGNUM); + emit_insn (gen_rtx_SET (reg10, GEN_INT (allocate & 0xffff))); + emit_insn (gen_insv_immdi (reg10, GEN_INT (16), + GEN_INT ((allocate & 0xffff0000) >> 16))); + emit_insn (gen_sub3_insn (reg10, stack_pointer_rtx, reg10)); + + ok_label = gen_label_rtx (); + + /* If function uses stacked arguments save the old stack value so morestack + can return it. */ + reg11 = gen_rtx_REG (Pmode, R11_REGNUM); + if (crtl->args.size + || cfun->machine->frame.saved_varargs_size) + emit_move_insn (reg11, stack_pointer_rtx); + + /* x12 holds the continuation address used to return to function. */ + reg12 = gen_rtx_REG (Pmode, R12_REGNUM); + aarch64_expand_mov_immediate (reg12, gen_rtx_LABEL_REF (VOIDmode, ok_label)); + + /* Jump to __morestack call if current ss guard is not suffice. */ + cc = aarch64_gen_compare_reg (GE, ssvalue, reg10); + cmp = gen_rtx_fmt_ee (GE, VOIDmode, cc, const0_rtx); + jump = gen_split_stack_cond_call (morestack_ref, cmp, ok_label, reg12); + + aarch64_emit_unlikely_jump (jump); + JUMP_LABEL (jump) = ok_label; + LABEL_NUSES (ok_label)++; + + /* __morestack will call us here. */ + emit_label (ok_label); +} + +/* Implement TARGET_ASM_FILE_END. */ + +static void +aarch64_file_end (void) +{ + file_end_indicate_exec_stack (); + + if (flag_split_stack) + { + file_end_indicate_split_stack (); + + /* Emit a reference to special symbol that LIBC uses to declare it + supports the split-stack before TCB. */ + switch_to_section (data_section); + fprintf (asm_out_file, "\t.align 3\n"); + fprintf (asm_out_file, "\t.quad __libc_tcb_private_ss\n"); + } +} + +/* Return the internal arg pointer used for function incoming arguments. */ + +static rtx +aarch64_internal_arg_pointer (void) +{ + if (flag_split_stack + && (lookup_attribute ("no_split_stack", DECL_ATTRIBUTES (cfun->decl)) + == NULL)) + { + if (cfun->machine->frame.split_stack_arg_pointer == NULL_RTX) + { + rtx pat; + + cfun->machine->frame.split_stack_arg_pointer = gen_reg_rtx (Pmode); + REG_POINTER (cfun->machine->frame.split_stack_arg_pointer) = 1; + + /* Put the pseudo initialization right after the note at the + beginning of the function. */ + pat = gen_rtx_SET (cfun->machine->frame.split_stack_arg_pointer, + gen_rtx_REG (Pmode, R11_REGNUM)); + push_topmost_sequence (); + emit_insn_after (pat, get_insns ()); + pop_topmost_sequence (); + } + return plus_constant (Pmode, cfun->machine->frame.split_stack_arg_pointer, + FIRST_PARM_OFFSET (current_function_decl)); + } + return virtual_incoming_args_rtx; +} + +/* Emit -fsplit-stack dynamic stack allocation space check. */ + +void +aarch64_split_stack_space_check (rtx size, rtx label) +{ + rtx ssvalue, cc, cmp, jump, temp; + rtx requested = gen_reg_rtx (Pmode); + + /* Load __private_ss from TCB. */ + ssvalue = aarch64_load_split_stack_value (false); + + temp = gen_reg_rtx (Pmode); + + /* And compare it with frame pointer plus required stack. */ + size = force_reg (Pmode, size); + emit_move_insn (requested, gen_rtx_MINUS (Pmode, stack_pointer_rtx, size)); + + /* Jump to label call if current ss guard is not suffice. */ + cc = aarch64_gen_compare_reg (LT, temp, ssvalue); + cmp = gen_rtx_fmt_ee (GEU, VOIDmode, cc, const0_rtx); + jump = emit_jump_insn (gen_condjump (cmp, cc, label)); + JUMP_LABEL (jump) = label; +} + /* Target-specific selftests. */ #if CHECKING_P @@ -14754,6 +14920,9 @@ aarch64_run_selftests (void) #undef TARGET_ASM_FILE_START #define TARGET_ASM_FILE_START aarch64_start_file +#undef TARGET_ASM_FILE_END +#define TARGET_ASM_FILE_END aarch64_file_end + #undef TARGET_ASM_OUTPUT_MI_THUNK #define TARGET_ASM_OUTPUT_MI_THUNK aarch64_output_mi_thunk @@ -14839,6 +15008,9 @@ aarch64_run_selftests (void) #undef TARGET_FRAME_POINTER_REQUIRED #define TARGET_FRAME_POINTER_REQUIRED aarch64_frame_pointer_required +#undef TARGET_INTERNAL_ARG_POINTER +#define TARGET_INTERNAL_ARG_POINTER aarch64_internal_arg_pointer + #undef TARGET_GIMPLE_FOLD_BUILTIN #define TARGET_GIMPLE_FOLD_BUILTIN aarch64_gimple_fold_builtin diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h index e4fb96f..510f60a 100644 --- a/gcc/config/aarch64/aarch64.h +++ b/gcc/config/aarch64/aarch64.h @@ -594,6 +594,9 @@ struct GTY (()) aarch64_frame unsigned wb_candidate2; bool laid_out; + + /* Alternative internal arg pointer for -fsplit-stack. */ + rtx split_stack_arg_pointer; }; typedef struct GTY (()) machine_function diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md index 5adc5ed..b0141f9 100644 --- a/gcc/config/aarch64/aarch64.md +++ b/gcc/config/aarch64/aarch64.md @@ -150,6 +150,7 @@ UNSPECV_SET_FPSR ; Represent assign of FPSR content. UNSPECV_BLOCKAGE ; Represent a blockage UNSPECV_PROBE_STACK_RANGE ; Represent stack range probing. + UNSPECV_SPLIT_STACK_CALL ; Represent a morestack call ] ) @@ -5572,3 +5573,58 @@ ;; ldp/stp peephole patterns (include "aarch64-ldpstp.md") + +;; Handle -fsplit-stack +(define_expand "split_stack_prologue" + [(const_int 0)] + "" +{ + aarch64_expand_split_stack_prologue (); + DONE; +}) + +;; If there are operand 0 bytes available on the stack, jump to +;; operand 1. +(define_expand "split_stack_space_check" + [(set (match_dup 2) (compare:CC (match_dup 3) (match_dup 2))) + (set (pc) (if_then_else + (geu (match_dup 4) (const_int 0)) + (label_ref (match_operand 1)) + (pc)))] + "" +{ + aarch64_split_stack_space_check (operands[0], operands[1]); + DONE; +}) + +;; A __morestack call using branch + +(define_expand "split_stack_cond_call" + [(match_operand 0 "aarch64_call_insn_operand" "") + (match_operand 1 "" "") + (match_operand 2 "" "") + (match_operand 3 "" "")] + "" +{ + emit_jump_insn (gen_split_stack_cond_call_di (operands[0], operands[1], + operands[2], operands[3])); + DONE; +}) + + +(define_insn "split_stack_cond_call_<mode>" + [(set (pc) + (if_then_else + (match_operand 1 "aarch64_comparison_operator" "") + (label_ref (match_operand 2 "" "")) + (pc))) + (set (reg:P 1) (unspec_volatile:P [(match_operand:P 0 "aarch64_call_insn_operand" "") + (reg:P 1)] + UNSPECV_SPLIT_STACK_CALL)) + (use (match_operand:P 3 "register_operand" ""))] + "" + { + return aarch64_gen_far_branch (operands, 0, "Lbcond", "b%M1\\t"); + } + [(set_attr "type" "branch")] +) diff --git a/libgcc/config.host b/libgcc/config.host index 9472a60..d6f4312 100644 --- a/libgcc/config.host +++ b/libgcc/config.host @@ -347,6 +347,7 @@ aarch64*-*-linux*) md_unwind_header=aarch64/linux-unwind.h tmake_file="${tmake_file} ${cpu_type}/t-aarch64" tmake_file="${tmake_file} ${cpu_type}/t-softfp t-softfp t-crtfm" + tmake_file="${tmake_file} t-stack aarch64/t-stack-aarch64" ;; alpha*-*-linux*) tmake_file="${tmake_file} alpha/t-alpha alpha/t-ieee t-crtfm alpha/t-linux" diff --git a/libgcc/config/aarch64/morestack-c.c b/libgcc/config/aarch64/morestack-c.c new file mode 100644 index 0000000..607ef05 --- /dev/null +++ b/libgcc/config/aarch64/morestack-c.c @@ -0,0 +1,85 @@ +/* AArch64 support for -fsplit-stack. + * Copyright (C) 2016 Free Software Foundation, Inc. + * + * This file is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 3, or (at your option) any + * later version. + * + * This file is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * Under Section 7 of GPL version 3, you are granted additional + * permissions described in the GCC Runtime Library Exception, version + * 3.1, as published by the Free Software Foundation. + * + * You should have received a copy of the GNU General Public License and + * a copy of the GCC Runtime Library Exception along with this program; + * see the files COPYING3 and COPYING.RUNTIME respectively. If not, see + * <http://www.gnu.org/licenses/>. + */ + +#ifndef inhibit_libc + +#include <stdint.h> +#include <stdlib.h> +#include <stddef.h> +#include "generic-morestack.h" + +#define INITIAL_STACK_SIZE 0x4000 +#define BACKOFF 0x1000 + +void __generic_morestack_set_initial_sp (void *sp, size_t len); +void *__morestack_get_guard (void); +void __morestack_set_guard (void *); +void *__morestack_make_guard (void *stack, size_t size); +void __morestack_load_mmap (void); + +/* split-stack area position from thread pointer. */ +#define SPLITSTACK_PTR_TP (-8) + +/* Initialize the stack guard when the program starts or when a new + thread. This is called from a constructor using ctors section. */ +void +__stack_split_initialize (void) +{ + register uintptr_t* sp __asm__ ("sp"); + uintptr_t *ss = (uintptr_t*)((char*)__builtin_thread_pointer () + + SPLITSTACK_PTR_TP); + *ss = (uintptr_t)sp - INITIAL_STACK_SIZE; + __generic_morestack_set_initial_sp (sp, INITIAL_STACK_SIZE); +} + +/* Return current __private_ss. */ +void * +__morestack_get_guard (void) +{ + void **ss = (void**)((char*)__builtin_thread_pointer () + + SPLITSTACK_PTR_TP); + return *ss; +} + +/* Set __private_ss to ptr. */ +void +__morestack_set_guard (void *ptr) +{ + void **ss = (void**)((char*)__builtin_thread_pointer () + + SPLITSTACK_PTR_TP); + *ss = ptr; +} + +/* Return the stack guard value for given stack. */ +void * +__morestack_make_guard (void *stack, size_t size) +{ + return (void*)((uintptr_t)stack - size + BACKOFF); +} + +/* Make __stack_split_initialize a high priority constructor. */ +static void (*const ctors []) + __attribute__ ((used, section (".ctors.65535"), aligned (sizeof (void *)))) + = { __stack_split_initialize, __morestack_load_mmap }; + +#endif /* !defined (inhibit_libc) */ diff --git a/libgcc/config/aarch64/morestack.S b/libgcc/config/aarch64/morestack.S new file mode 100644 index 0000000..c8a3d82 --- /dev/null +++ b/libgcc/config/aarch64/morestack.S @@ -0,0 +1,246 @@ +# AArch64 support for -fsplit-stack. +# Copyright (C) 2016 Free Software Foundation, Inc. + +# This file is part of GCC. + +# GCC is free software; you can redistribute it and/or modify it under +# the terms of the GNU General Public License as published by the Free +# Software Foundation; either version 3, or (at your option) any later +# version. + +# GCC is distributed in the hope that it will be useful, but WITHOUT ANY +# WARRANTY; without even the implied warranty of MERCHANTABILITY or +# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +# for more details. + +# Under Section 7 of GPL version 3, you are granted additional +# permissions described in the GCC Runtime Library Exception, version +# 3.1, as published by the Free Software Foundation. + +# You should have received a copy of the GNU General Public License and +# a copy of the GCC Runtime Library Exception along with this program; +# see the files COPYING3 and COPYING.RUNTIME respectively. If not, see +# <http://www.gnu.org/licenses/>. + +/* Define an entry point visible from C. */ +#define ENTRY(name) \ + .globl name; \ + .type name,%function; \ + .align 4; \ + name##: + +#define END(name) \ + .size name,.-name + +/* __morestack frame size. */ +#define MORESTACK_FRAMESIZE 112 +/* Offset from __morestack frame where the new stack size is saved and + passed to __generic_morestack. */ +#define NEWSTACK_SAVE 96 + +#define BACKOFF 0x1000 +# Large excess allocated when calling non-split-stack code. +#define NON_SPLIT_STACK 0x100000 + +/* split-stack area position from thread pointer. */ +#define SPLITSTACK_PTR_TP -8 + + .text +ENTRY(__morestack_non_split) + .cfi_startproc +# We use a cleanup to restore the tcbhead_t.__private_ss if +# an exception is thrown through this code. + add x10, x10, NON_SPLIT_STACK + .cfi_endproc +END(__morestack_non_split) +# Fall through into __morestack + +# This function is called with non-standard calling conventions, on entry +# x10 is the requested stack pointer. The split-stack prologue is in the +# form: +# +# function: +# mrs x9, tpidr_el0 +# mov x10, <required stack allocation> +# movk x10, #0x0, lsl #16 +# sub x10, sp, x10 +# mov x11, sp # if function has stacked arguments +# adrp x12, main_fn_entry +# add x12, x12, :lo12:.L2 +# cmp x9, x10 +# b.lt <main_fn_entry> +# b __morestack +# main_fn_entry: +# [function prologue] +# +# The N bit is also restored to indicate that the function is called +# (so the prologue addition can set up the argument pointer correctly). + +ENTRY(__morestack) +.LFB1: + .cfi_startproc + +#ifdef __PIC__ + .cfi_personality 0x9b,DW.ref.__gcc_personality_v0 + .cfi_lsda 0x1b,.LLSDA1 +#else + .cfi_personality 0x3,__gcc_personality_v0 + .cfi_lsda 0x3,.LLSDA1 +#endif + + # Calculate requested stack size. + sub x10, sp, x10 + # Save parameters + stp x29, x30, [sp, -MORESTACK_FRAMESIZE]! + .cfi_def_cfa_offset MORESTACK_FRAMESIZE + .cfi_offset 29, -MORESTACK_FRAMESIZE + .cfi_offset 30, -MORESTACK_FRAMESIZE+8 + add x29, sp, 0 + .cfi_def_cfa_register 29 + # Adjust the requested stack size for the frame pointer save. + stp x0, x1, [sp, 16] + stp x2, x3, [sp, 32] + add x10, x10, BACKOFF + stp x4, x5, [sp, 48] + stp x6, x7, [sp, 64] + stp x8, x12, [sp, 80] + str x10, [sp, 96] + + # void __morestack_block_signals (void) + bl __morestack_block_signals + + # void *__generic_morestack (size_t *pframe_size, + # void *old_stack, + # size_t param_size) + # pframe_size: is the size of the required stack frame (the function + # amount of space remaining on the allocated stack). + # old_stack: points at the parameters the old stack + # param_size: size in bytes of parameters to copy to the new stack. + add x0, x29, NEWSTACK_SAVE + add x1, x29, MORESTACK_FRAMESIZE + mov x2, 0 + bl __generic_morestack + + # Start using new stack + mov sp, x0 + + # Set __private_ss stack guard for the new stack. + ldr x9, [x29, NEWSTACK_SAVE] + add x0, x0, BACKOFF + sub x0, x0, x9 +.LEHB0: + mrs x1, tpidr_el0 + str x0, [x1, SPLITSTACK_PTR_TP] + + # void __morestack_unblock_signals (void) + bl __morestack_unblock_signals + + # Set up for a call to the target function. + ldp x0, x1, [x29, 16] + ldp x2, x3, [x29, 32] + ldp x4, x5, [x29, 48] + ldp x6, x7, [x29, 64] + ldp x8, x12, [x29, 80] + add x11, x29, MORESTACK_FRAMESIZE + # Indicate __morestack was called. + cmp x12, 0 + blr x12 + + stp x0, x1, [x29, 16] + stp x2, x3, [x29, 32] + stp x4, x5, [x29, 48] + stp x6, x7, [x29, 64] + + bl __morestack_block_signals + + # void *__generic_releasestack (size_t *pavailable) + add x0, x29, NEWSTACK_SAVE + bl __generic_releasestack + + # Reset __private_ss stack guard to value for old stack + ldr x9, [x29, NEWSTACK_SAVE] + add x0, x0, BACKOFF + sub x0, x0, x9 + + # Update TCB split stack field +.LEHE0: + mrs x1, tpidr_el0 + str x0, [x1, SPLITSTACK_PTR_TP] + + bl __morestack_unblock_signals + + # Use old stack again. + add sp, x29, MORESTACK_FRAMESIZE + + ldp x0, x1, [x29, 16] + ldp x2, x3, [x29, 32] + ldp x4, x5, [x29, 48] + ldp x6, x7, [x29, 64] + ldp x29, x30, [x29] + + .cfi_remember_state + .cfi_restore 30 + .cfi_restore 29 + .cfi_def_cfa 31, 0 + + ret + +# This is the cleanup code called by the stack unwinder when +# unwinding through code between .LEHB0 and .LEHE0 above. +cleanup: + .cfi_restore_state + # Reuse the new stack allocation to save/restore the + # exception header + str x0, [x29, NEWSTACK_SAVE] + # size_t __generic_findstack (void *stack) + add x0, x29, MORESTACK_FRAMESIZE + bl __generic_findstack + sub x0, x29, x0 + add x0, x0, BACKOFF + # Restore split-stack guard value + mrs x1, tpidr_el0 + str x0, [x1, SPLITSTACK_PTR_TP] + ldr x0, [x29, NEWSTACK_SAVE] + b _Unwind_Resume + .cfi_endproc +END(__morestack) + + .section .gcc_except_table,"a",@progbits + .align 4 +.LLSDA1: + # @LPStart format (omit) + .byte 0xff + # @TType format (omit) + .byte 0xff + # Call-site format (uleb128) + .byte 0x1 + # Call-site table length + .uleb128 .LLSDACSE1-.LLSDACSB1 +.LLSDACSB1: + # region 0 start + .uleb128 .LEHB0-.LFB1 + # length + .uleb128 .LEHE0-.LEHB0 + # landing pad + .uleb128 cleanup-.LFB1 + # no action (ie a cleanup) + .uleb128 0 +.LLSDACSE1: + + + .global __gcc_personality_v0 +#ifdef __PIC__ + # Build a position independent reference to the personality function. + .hidden DW.ref.__gcc_personality_v0 + .weak DW.ref.__gcc_personality_v0 + .section .data.DW.ref.__gcc_personality_v0,"awG",@progbits,DW.ref.__gcc_personality_v0,comdat + .type DW.ref.__gcc_personality_v0, @object + .align 3 +DW.ref.__gcc_personality_v0: + .size DW.ref.__gcc_personality_v0, 8 + .quad __gcc_personality_v0 +#endif + + .section .note.GNU-stack,"",@progbits + .section .note.GNU-split-stack,"",@progbits + .section .note.GNU-no-split-stack,"",@progbits diff --git a/libgcc/config/aarch64/t-stack-aarch64 b/libgcc/config/aarch64/t-stack-aarch64 new file mode 100644 index 0000000..4babb4e --- /dev/null +++ b/libgcc/config/aarch64/t-stack-aarch64 @@ -0,0 +1,3 @@ +# Makefile fragment to support -fsplit-stack for aarch64. +LIB2ADD_ST += $(srcdir)/config/aarch64/morestack.S \ + $(srcdir)/config/aarch64/morestack-c.c diff --git a/libgcc/generic-morestack.c b/libgcc/generic-morestack.c index adbe436..e91ceb4 100644 --- a/libgcc/generic-morestack.c +++ b/libgcc/generic-morestack.c @@ -943,6 +943,7 @@ __splitstack_find (void *segment_arg, void *sp, size_t *len, nsp -= 2 * 160; #elif defined __s390__ nsp -= 2 * 96; +#elif defined __aarch64__ #else #error "unrecognized target" #endif
This is an update patch from my previous version (v3) based mainly on glibc comments on exported loader symbol [1]. The changes from previous version are: - Remove __tcb_private_ss call on libgcc and emit a data usage on glibc symbol when split-stack is used. This removes the runtime errors when running on older glibc and instead make the loader fails with a missing symbol. - Add glibc version check on split-stack support check. - Some comments fixes on morestack.S. - Remove some compile warnings on morestack-c.c. -- This patch adds the split-stack support on aarch64 (PR #67877). As for other ports this patch should be used along with glibc and gold support. The support is done similar to other architectures: a split-stack field is allocated before TCB by glibc, a target-specific __morestack implementation and helper functions are added in libgcc and compiler supported in adjusted (split-stack prologue, va_start for argument handling). I also plan to send the gold support to adjust stack allocation acrosss split-stack and default code calls. Current approach is to set the final stack adjustments using a 2 instructions at most (mov/movk) which limits stack allocation to upper limit of 4GB. The morestack call is non standard with x10 hollding the requested stack pointer, x11 the argument pointer (if required), and x12 to return continuation address. Unwinding is handled by a personality routine that knows how to find stack segments. Split-stack prologue on function entry is as follow (this goes before the usual function prologue): function: mrs x9, tpidr_el0 mov x10, <required stack allocation> movk x10, #0x0, lsl #16 sub x10, sp, x10 mov x11, sp # if function has stacked arguments adrp x12, main_fn_entry add x12, x12, :lo12:.L2 cmp x9, x10 b.lt <main_fn_entry> b __morestack main_fn_entry: [function prologue] Notes: 1. Even if a function does not allocate a stack frame, a split-stack prologue is created. It is to avoid issues with tail call for external symbols which might require linker adjustment (libgo/runtime/go-varargs.c). 2. Basic-block reordering (enabled with -O2) will move split-stack TCB ldr to after the required stack calculation. 3. Similar to powerpc, When the linker detects a call from split-stack to non-split-stack code, it adds 16k (or more) to the value found in "allocate" instructions (so non-split-stack code gets a larger stack). The amount is tunable by a linker option. The edit means aarch64 does not need to implement __morestack_non_split, necessary on x86 because insufficient space is available there to edit the stack comparison code. This feature is only implemented in the GNU gold linker. 4. AArch64 does not handle >4G stack initially and although it is possible to implement it, limiting to 4G allows to materize the allocation with only 2 instructions (mov + movk) and thus simplifying the linker adjustments required. Supporting multiple threads each requiring more than 4G of stack is probably not that important, and likely to OOM at run time. 5. The TCB support on GLIBC is meant to be included in version 2.26. 6. The continuation address materialized on x12 is done using 'adrp' plus add and a static relocation. Current code uses the aarch64_expand_mov_immediate function and since a better alternative would be 'adp', it could be a future optimization (not implemented in this patch). [1] https://sourceware.org/ml/libc-alpha/2017-02/msg00272.html libgcc/ChangeLog: * libgcc/config.host: Use t-stack and t-statck-aarch64 for aarch64*-*-linux. * libgcc/config/aarch64/morestack-c.c: New file. * libgcc/config/aarch64/morestack.S: Likewise. * libgcc/config/aarch64/t-stack-aarch64: Likewise. * libgcc/generic-morestack.c (__splitstack_find): Add aarch64-specific code. gcc/ChangeLog: * common/config/aarch64/aarch64-common.c (aarch64_supports_split_stack): New function. (TARGET_SUPPORTS_SPLIT_STACK): New macro. * gcc/config/aarch64/aarch64-linux.h (TARGET_ASM_FILE_END): Remove macro. * gcc/config/aarch64/aarch64-protos.h: Add aarch64_expand_split_stack_prologue and aarch64_split_stack_space_check. * gcc/config/aarch64/aarch64.c (aarch64_gen_far_branch): Add suport to emit 'b' instruction to rtx different than LABEL_REF. (aarch64_expand_builtin_va_start): Use internal argument pointer instead of virtual_incoming_args_rtx. (morestack_ref): New symbol. (aarch64_load_split_stack_value): New function. (aarch64_expand_split_stack_prologue): Likewise. (aarch64_internal_arg_pointer): Likewise. (aarch64_split_stack_space_check): Likewise. (aarch64_file_end): Emit the split-stack note sections. (TARGET_ASM_FILE_END): New macro. (TARGET_INTERNAL_ARG_POINTER): Likewise. * gcc/config/aarch64/aarch64.h (aarch64_frame): Add split_stack_arg_pointer to setup the argument pointer when using split-stack. * gcc/config/aarch64/aarch64.md (UNSPECV_SPLIT_STACK_RETURN): Likewise. (split_stack_prologue): New expand. (split_stack_space_check): Likewise. (split_stack_cond_call): Likewise. --- gcc/common/config/aarch64/aarch64-common.c | 31 +++- gcc/config/aarch64/aarch64-linux.h | 2 - gcc/config/aarch64/aarch64-protos.h | 2 + gcc/config/aarch64/aarch64.c | 176 ++++++++++++++++++++- gcc/config/aarch64/aarch64.h | 3 + gcc/config/aarch64/aarch64.md | 56 +++++++ libgcc/config.host | 1 + libgcc/config/aarch64/morestack-c.c | 85 ++++++++++ libgcc/config/aarch64/morestack.S | 246 +++++++++++++++++++++++++++++ libgcc/config/aarch64/t-stack-aarch64 | 3 + libgcc/generic-morestack.c | 1 + 11 files changed, 601 insertions(+), 5 deletions(-) create mode 100644 libgcc/config/aarch64/morestack-c.c create mode 100644 libgcc/config/aarch64/morestack.S create mode 100644 libgcc/config/aarch64/t-stack-aarch64 -- 2.7.4