@@ -107,6 +107,21 @@ aarch64_handle_option (struct gcc_options *opts,
}
}
+/* -fsplit-stack uses a TCB field available on glibc-2.25. GLIBC also
+ exports symbol, __tcb_private_ss, to signal it has the field available
+ on TCB allocation. 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)
+{
+ return true;
+}
+
+#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 +355,3 @@ aarch64_rewrite_mcpu (int argc, const char **argv)
}
#undef AARCH64_CPU_NAME_LENGTH
-
@@ -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. */
@@ -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);
@@ -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 +14687,159 @@ 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 ();
+}
+
+/* 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 +14912,9 @@ 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 +15000,9 @@ 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
@@ -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
@@ -135,6 +135,7 @@
UNSPEC_VSTRUCTDUMMY
UNSPEC_SP_SET
UNSPEC_SP_TEST
+ UNSPEC_STACK_CHECK
UNSPEC_RSQRT
UNSPEC_RSQRTE
UNSPEC_RSQRTS
@@ -150,6 +151,7 @@
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 +5574,58 @@
;; 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")]
+)
@@ -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"
new file mode 100644
@@ -0,0 +1,88 @@
+/* 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);
+
+/* We declare is as weak so it fails either at stack linking or
+ at runtime if the GLIBC does not have the required TCB field. */
+extern void __tcb_private_ss (void) __attribute__ ((weak));
+
+/* 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)
+{
+ __tcb_private_ss ();
+
+ register uintptr_t* sp __asm__ ("sp");
+ uintptr_t *ss = ((char *)__builtin_thread_pointer () + SPLITSTACK_PTR_TP);
+ *ss = sp - INITIAL_STACK_SIZE;
+ __generic_morestack_set_initial_sp (sp, INITIAL_STACK_SIZE);
+}
+
+/* Return current __private_ss. */
+void *
+__morestack_get_guard (void)
+{
+ uintptr_t *ss = ((char *)__builtin_thread_pointer () + SPLITSTACK_PTR_TP);
+ return *ss;
+}
+
+/* Set __private_ss to ptr. */
+void
+__morestack_set_guard (void *ptr)
+{
+ uintptr_t *ss = ((char *)__builtin_thread_pointer () + SPLITSTACK_PTR_TP);
+ *ss = (uintptr_t) 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) */
new file mode 100644
@@ -0,0 +1,254 @@
+# 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
+# sub x10, sp, N & 0xfff000
+# sub x10, x10, N & 0xfff
+# ldr x9, [x9, 16]
+# adrp x12, main_fn_entry
+# add x12, x12, :lo12:main_fn_entry
+# [mov x11, sp] # If function has stacked arguments
+# cmp x9, x10
+# b.lt main_fn_entry
+# b __morestack
+# main_fn_entry: [x11 is argument pointer]
+# [prolog]
+#
+# The normal function prologue follows here, with a small addition at the
+# end to set up the argument pointer if required (the prolog):
+#
+# [...] # default function prologue
+# b.lt function:
+# function:
+#
+#
+# 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 tcbhead_t.__private_ss
+ 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
new file mode 100644
@@ -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
@@ -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
Changes from previous version: - The split-stack are is now allocated before the thread pointer (instead of tcbhead_t which is positioned after it) as decribed in glibc patch [1]. It has the advantage to not require linker changes to take in consideration the new tcbhead_t size and it also fixed the regression I was seeing on the previous version of this patch at runtime/pprof: __splitstack_setcontext updates some internal TLS variables and with split-stack trying to update a larger tcbhead_t field it clobbered the tls variable when using a default static linker (which expected a default tcbhead_t structure as size of 16). - Function aarch64_split_stack_space_check is changed back to previous implementation because a wrong comment in my previous version lead to wrong assumptions on [2]. The function will generate a jump to 'label' variable (which will call __morestack_allocate_stack_space) not the arch-specific __morestack implementation. I corrected the comment as wellA - Change the stack adjustments to always use 2 instructions. [3] I am not seeing any more issue when using split-stack neither check-go regressions with this version. [1] https://sourceware.org/ml/libc-alpha/2017-02/msg00247.html [2] https://gcc.gnu.org/ml/gcc-patches/2017-01/msg00093.html [3] https://gcc.gnu.org/ml/gcc-patches/2017-02/msg00055.html -- 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 __private_ss field is added on TCB in 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 similar to powerpc one: at most 2 GB of stack allocation is support so stack adjustments can be done with 2 instructions (either just a movn plus nop or a movn followed by movk). The morestack call is non standard with x10 hollding the requested stack pointer, x11 the argument pointer, 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 0x0 add 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 2.25. 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). 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: PR 67877 * 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_expand_prologue): Setup the argument pointer (x10) for split-stack. (aarch64_expand_builtin_va_start): Use internal argument pointer instead of virtual_incoming_args_rtx. (morestack_ref): New symbol. (aarch64_expand_split_stack_prologue): New function. (aarch64_file_end): Emit the split-stack note sections. (aarch64_internal_arg_pointer): Likewise. (aarch64_live_on_entry): Set the argument pointer for split-stack. (aarch64_split_stack_space_check): Likewise. (TARGET_ASM_FILE_END): New macro. (TARGET_EXTRA_LIVE_ON_ENTRY): Likewise. (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 (UNSPEC_STACK_CHECK): New unspec. (UNSPECV_SPLIT_STACK_RETURN): Likewise. (split_stack_prologue): New expand. (split_stack_space_check): Likewise. (split_stack_cond_call): New expand. --- gcc/common/config/aarch64/aarch64-common.c | 16 +- gcc/config/aarch64/aarch64-linux.h | 2 - gcc/config/aarch64/aarch64-protos.h | 2 + gcc/config/aarch64/aarch64.c | 168 ++++++++++++++++++- gcc/config/aarch64/aarch64.h | 3 + gcc/config/aarch64/aarch64.md | 57 +++++++ libgcc/config.host | 1 + libgcc/config/aarch64/morestack-c.c | 88 ++++++++++ libgcc/config/aarch64/morestack.S | 254 +++++++++++++++++++++++++++++ libgcc/config/aarch64/t-stack-aarch64 | 3 + libgcc/generic-morestack.c | 1 + 11 files changed, 590 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