| Message ID | 20180713161136.29104-10-christophe.lyon@st.com |
|---|---|
| State | New |
| Headers | show |
| Series | FDPIC ABI for ARM | expand |
Hi Christophe, On 13/07/18 17:11, christophe.lyon@st.com wrote: > From: Christophe Lyon <christophe.lyon@linaro.org> > > In FDPIC mode, the trampoline generated to support pointers to nested > functions looks like: > > .word trampoline address > .word trampoline GOT address > ldr r12, [pc, #8] > ldr r9, [pc, #8] > ldr pc, [pc] The comment in the code says the last one is: ldr pc, [pc, #8] ; #4 for Thumb2 I'm assuming the code one is correct. > .word static chain value > .word GOT address > .word function's address > > because in FDPIC function pointers are actually pointers to function > descriptors, we have to actually generate a function descriptor for > the trampoline. > > 2018-XX-XX Christophe Lyon <christophe.lyon@st.com> > Mickaël Guêné <mickael.guene@st.com> > > gcc/ > * config/arm/arm.c (arm_asm_trampoline_template): Add FDPIC > support. > (arm_trampoline_init): Likewise. > (arm_trampoline_init): Likewise. > * config/arm/arm.h (TRAMPOLINE_SIZE): Likewise. > > Change-Id: I4b5127261a9aefa0f0318f110574ec07a856aeb1 > > diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c > index 51da2bc..ffc9128 100644 > --- a/gcc/config/arm/arm.c > +++ b/gcc/config/arm/arm.c > @@ -3950,13 +3950,50 @@ arm_warn_func_return (tree decl) > .word static chain value > .word function's address > XXX FIXME: When the trampoline returns, r8 will be clobbered. */ > +/* In FDPIC mode, the trampoline looks like: > + .word trampoline address > + .word trampoline GOT address > + ldr r12, [pc, #8] ; #4 for Thumb2 > + ldr r9, [pc, #8] ; #4 for Thumb2 > + ldr pc, [pc, #8] ; #4 for Thumb2 > + .word static chain value > + .word GOT address > + .word function's address > +*/ > static void > arm_asm_trampoline_template (FILE *f) > { > fprintf (f, "\t.syntax unified\n"); > > - if (TARGET_ARM) > + if (TARGET_FDPIC) > + { > + /* The first two words are a function descriptor pointing to the > + trampoline code just below. */ > + if (TARGET_ARM) > + fprintf (f, "\t.arm\n"); > + else if (TARGET_THUMB2) > + fprintf (f, "\t.thumb\n"); > + else > + /* Only ARM and Thumb-2 are supported. */ > + gcc_assert ( !TARGET_ARM && !TARGET_THUMB2); > + This cannot trigger based on the two clauses above. I think you want to just make it gcc_unreachable (). > + assemble_aligned_integer (UNITS_PER_WORD, const0_rtx); > + assemble_aligned_integer (UNITS_PER_WORD, const0_rtx); > + /* Trampoline code which sets the static chain register but also > + PIC register before jumping into real code. */ > + asm_fprintf (f, "\tldr\t%r, [%r, #%d]\n", > + STATIC_CHAIN_REGNUM, PC_REGNUM, > + TARGET_THUMB2 ? 8 : 4); > + asm_fprintf (f, "\tldr\t%r, [%r, #%d]\n", > + PIC_OFFSET_TABLE_REGNUM, PC_REGNUM, > + TARGET_THUMB2 ? 8 : 4); > + asm_fprintf (f, "\tldr\t%r, [%r, #%d]\n", > + PC_REGNUM, PC_REGNUM, > + TARGET_THUMB2 ? 8 : 4); > + assemble_aligned_integer (UNITS_PER_WORD, const0_rtx); > + } > + else if (TARGET_ARM) > { > fprintf (f, "\t.arm\n"); > asm_fprintf (f, "\tldr\t%r, [%r, #0]\n", STATIC_CHAIN_REGNUM, PC_REGNUM); > @@ -3997,12 +4034,37 @@ arm_trampoline_init (rtx m_tramp, tree fndecl, rtx chain_value) > emit_block_move (m_tramp, assemble_trampoline_template (), > GEN_INT (TRAMPOLINE_SIZE), BLOCK_OP_NORMAL); > > - mem = adjust_address (m_tramp, SImode, TARGET_32BIT ? 8 : 12); > - emit_move_insn (mem, chain_value); > + if (TARGET_FDPIC) > + { > + rtx funcdesc = XEXP (DECL_RTL (fndecl), 0); > + rtx fnaddr = gen_rtx_MEM (Pmode, funcdesc); > + rtx gotaddr = gen_rtx_MEM (Pmode, plus_constant (Pmode, funcdesc, 4)); > + rtx trampoline_code_start > + = plus_constant (Pmode, XEXP (m_tramp, 0), TARGET_THUMB2 ? 9 : 8); 9? Can you comment on this value? > + > + /* Write initial funcdesc which points to the trampoline. */ > + mem = adjust_address (m_tramp, SImode, 0); > + emit_move_insn (mem, trampoline_code_start); > + mem = adjust_address (m_tramp, SImode, 4); > + emit_move_insn (mem, gen_rtx_REG (Pmode, PIC_OFFSET_TABLE_REGNUM)); > + /* Setup static chain. */ > + mem = adjust_address (m_tramp, SImode, 20); > + emit_move_insn (mem, chain_value); > + /* GOT + real function entry point. */ > + mem = adjust_address (m_tramp, SImode, 24); > + emit_move_insn (mem, gotaddr); > + mem = adjust_address (m_tramp, SImode, 28); > + emit_move_insn (mem, fnaddr); > + } > + else > + { > + mem = adjust_address (m_tramp, SImode, TARGET_32BIT ? 8 : 12); > + emit_move_insn (mem, chain_value); > > - mem = adjust_address (m_tramp, SImode, TARGET_32BIT ? 12 : 16); > - fnaddr = XEXP (DECL_RTL (fndecl), 0); > - emit_move_insn (mem, fnaddr); > + mem = adjust_address (m_tramp, SImode, TARGET_32BIT ? 12 : 16); > + fnaddr = XEXP (DECL_RTL (fndecl), 0); > + emit_move_insn (mem, fnaddr); > + } > > a_tramp = XEXP (m_tramp, 0); > emit_library_call (gen_rtx_SYMBOL_REF (Pmode, "__clear_cache"), > @@ -4016,7 +4078,9 @@ arm_trampoline_init (rtx m_tramp, tree fndecl, rtx chain_value) > static rtx > arm_trampoline_adjust_address (rtx addr) > { > - if (TARGET_THUMB) > + /* For FDPIC don't fix trampoline address since it's a function > + descriptor and not a function address. */ > + if (TARGET_THUMB && !TARGET_FDPIC) > addr = expand_simple_binop (Pmode, IOR, addr, const1_rtx, > NULL, 0, OPTAB_LIB_WIDEN); > return addr; > diff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h > index 4671d64..22a65a1 100644 > --- a/gcc/config/arm/arm.h > +++ b/gcc/config/arm/arm.h > @@ -1581,7 +1581,7 @@ typedef struct > #define INIT_EXPANDERS arm_init_expanders () > > /* Length in units of the trampoline for entering a nested function. */ > -#define TRAMPOLINE_SIZE (TARGET_32BIT ? 16 : 20) > +#define TRAMPOLINE_SIZE (TARGET_FDPIC ? 32 : (TARGET_32BIT ? 16 : 20)) > > /* Alignment required for a trampoline in bits. */ > #define TRAMPOLINE_ALIGNMENT 32 > -- > 2.6.3 >
On Wed, 29 Aug 2018 at 13:01, Kyrill Tkachov <kyrylo.tkachov@foss.arm.com> wrote: > > Hi Christophe, > > On 13/07/18 17:11, christophe.lyon@st.com wrote: > > From: Christophe Lyon <christophe.lyon@linaro.org> > > > > In FDPIC mode, the trampoline generated to support pointers to nested > > functions looks like: > > > > .word trampoline address > > .word trampoline GOT address > > ldr r12, [pc, #8] > > ldr r9, [pc, #8] > > ldr pc, [pc] > > The comment in the code says the last one is: > ldr pc, [pc, #8] ; #4 for Thumb2 > > I'm assuming the code one is correct. Right, it looks like a typo in the commit message. > > > .word static chain value > > .word GOT address > > .word function's address > > > > because in FDPIC function pointers are actually pointers to function > > descriptors, we have to actually generate a function descriptor for > > the trampoline. > > > > 2018-XX-XX Christophe Lyon <christophe.lyon@st.com> > > Mickaël Guêné <mickael.guene@st.com> > > > > gcc/ > > * config/arm/arm.c (arm_asm_trampoline_template): Add FDPIC > > support. > > (arm_trampoline_init): Likewise. > > (arm_trampoline_init): Likewise. > > * config/arm/arm.h (TRAMPOLINE_SIZE): Likewise. > > > > Change-Id: I4b5127261a9aefa0f0318f110574ec07a856aeb1 > > > > diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c > > index 51da2bc..ffc9128 100644 > > --- a/gcc/config/arm/arm.c > > +++ b/gcc/config/arm/arm.c > > @@ -3950,13 +3950,50 @@ arm_warn_func_return (tree decl) > > .word static chain value > > .word function's address > > XXX FIXME: When the trampoline returns, r8 will be clobbered. */ > > +/* In FDPIC mode, the trampoline looks like: > > + .word trampoline address > > + .word trampoline GOT address > > + ldr r12, [pc, #8] ; #4 for Thumb2 > > + ldr r9, [pc, #8] ; #4 for Thumb2 > > + ldr pc, [pc, #8] ; #4 for Thumb2 > > + .word static chain value > > + .word GOT address > > + .word function's address > > +*/ > > static void > > arm_asm_trampoline_template (FILE *f) > > { > > fprintf (f, "\t.syntax unified\n"); > > > > - if (TARGET_ARM) > > + if (TARGET_FDPIC) > > + { > > + /* The first two words are a function descriptor pointing to the > > + trampoline code just below. */ > > + if (TARGET_ARM) > > + fprintf (f, "\t.arm\n"); > > + else if (TARGET_THUMB2) > > + fprintf (f, "\t.thumb\n"); > > + else > > + /* Only ARM and Thumb-2 are supported. */ > > + gcc_assert ( !TARGET_ARM && !TARGET_THUMB2); > > + > > This cannot trigger based on the two clauses above. I think you want to just make it gcc_unreachable (). > OK > > + assemble_aligned_integer (UNITS_PER_WORD, const0_rtx); > > + assemble_aligned_integer (UNITS_PER_WORD, const0_rtx); > > + /* Trampoline code which sets the static chain register but also > > + PIC register before jumping into real code. */ > > + asm_fprintf (f, "\tldr\t%r, [%r, #%d]\n", > > + STATIC_CHAIN_REGNUM, PC_REGNUM, > > + TARGET_THUMB2 ? 8 : 4); > > + asm_fprintf (f, "\tldr\t%r, [%r, #%d]\n", > > + PIC_OFFSET_TABLE_REGNUM, PC_REGNUM, > > + TARGET_THUMB2 ? 8 : 4); > > + asm_fprintf (f, "\tldr\t%r, [%r, #%d]\n", > > + PC_REGNUM, PC_REGNUM, > > + TARGET_THUMB2 ? 8 : 4); > > + assemble_aligned_integer (UNITS_PER_WORD, const0_rtx); > > + } > > + else if (TARGET_ARM) > > { > > fprintf (f, "\t.arm\n"); > > asm_fprintf (f, "\tldr\t%r, [%r, #0]\n", STATIC_CHAIN_REGNUM, PC_REGNUM); > > @@ -3997,12 +4034,37 @@ arm_trampoline_init (rtx m_tramp, tree fndecl, rtx chain_value) > > emit_block_move (m_tramp, assemble_trampoline_template (), > > GEN_INT (TRAMPOLINE_SIZE), BLOCK_OP_NORMAL); > > > > - mem = adjust_address (m_tramp, SImode, TARGET_32BIT ? 8 : 12); > > - emit_move_insn (mem, chain_value); > > + if (TARGET_FDPIC) > > + { > > + rtx funcdesc = XEXP (DECL_RTL (fndecl), 0); > > + rtx fnaddr = gen_rtx_MEM (Pmode, funcdesc); > > + rtx gotaddr = gen_rtx_MEM (Pmode, plus_constant (Pmode, funcdesc, 4)); > > + rtx trampoline_code_start > > + = plus_constant (Pmode, XEXP (m_tramp, 0), TARGET_THUMB2 ? 9 : 8); > > 9? Can you comment on this value? > The function start address is a offset 8, but in Thumb mode we want bit 0 set to 1 to indicate thumb-ness. > > + > > + /* Write initial funcdesc which points to the trampoline. */ > > + mem = adjust_address (m_tramp, SImode, 0); > > + emit_move_insn (mem, trampoline_code_start); > > + mem = adjust_address (m_tramp, SImode, 4); > > + emit_move_insn (mem, gen_rtx_REG (Pmode, PIC_OFFSET_TABLE_REGNUM)); > > + /* Setup static chain. */ > > + mem = adjust_address (m_tramp, SImode, 20); > > + emit_move_insn (mem, chain_value); > > + /* GOT + real function entry point. */ > > + mem = adjust_address (m_tramp, SImode, 24); > > + emit_move_insn (mem, gotaddr); > > + mem = adjust_address (m_tramp, SImode, 28); > > + emit_move_insn (mem, fnaddr); > > + } > > + else > > + { > > + mem = adjust_address (m_tramp, SImode, TARGET_32BIT ? 8 : 12); > > + emit_move_insn (mem, chain_value); > > > > - mem = adjust_address (m_tramp, SImode, TARGET_32BIT ? 12 : 16); > > - fnaddr = XEXP (DECL_RTL (fndecl), 0); > > - emit_move_insn (mem, fnaddr); > > + mem = adjust_address (m_tramp, SImode, TARGET_32BIT ? 12 : 16); > > + fnaddr = XEXP (DECL_RTL (fndecl), 0); > > + emit_move_insn (mem, fnaddr); > > + } > > > > a_tramp = XEXP (m_tramp, 0); > > emit_library_call (gen_rtx_SYMBOL_REF (Pmode, "__clear_cache"), > > @@ -4016,7 +4078,9 @@ arm_trampoline_init (rtx m_tramp, tree fndecl, rtx chain_value) > > static rtx > > arm_trampoline_adjust_address (rtx addr) > > { > > - if (TARGET_THUMB) > > + /* For FDPIC don't fix trampoline address since it's a function > > + descriptor and not a function address. */ > > + if (TARGET_THUMB && !TARGET_FDPIC) > > addr = expand_simple_binop (Pmode, IOR, addr, const1_rtx, > > NULL, 0, OPTAB_LIB_WIDEN); > > return addr; > > diff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h > > index 4671d64..22a65a1 100644 > > --- a/gcc/config/arm/arm.h > > +++ b/gcc/config/arm/arm.h > > @@ -1581,7 +1581,7 @@ typedef struct > > #define INIT_EXPANDERS arm_init_expanders () > > > > /* Length in units of the trampoline for entering a nested function. */ > > -#define TRAMPOLINE_SIZE (TARGET_32BIT ? 16 : 20) > > +#define TRAMPOLINE_SIZE (TARGET_FDPIC ? 32 : (TARGET_32BIT ? 16 : 20)) > > > > /* Alignment required for a trampoline in bits. */ > > #define TRAMPOLINE_ALIGNMENT 32 > > -- > > 2.6.3 > > >
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c index 51da2bc..ffc9128 100644 --- a/gcc/config/arm/arm.c +++ b/gcc/config/arm/arm.c @@ -3950,13 +3950,50 @@ arm_warn_func_return (tree decl) .word static chain value .word function's address XXX FIXME: When the trampoline returns, r8 will be clobbered. */ +/* In FDPIC mode, the trampoline looks like: + .word trampoline address + .word trampoline GOT address + ldr r12, [pc, #8] ; #4 for Thumb2 + ldr r9, [pc, #8] ; #4 for Thumb2 + ldr pc, [pc, #8] ; #4 for Thumb2 + .word static chain value + .word GOT address + .word function's address +*/ static void arm_asm_trampoline_template (FILE *f) { fprintf (f, "\t.syntax unified\n"); - if (TARGET_ARM) + if (TARGET_FDPIC) + { + /* The first two words are a function descriptor pointing to the + trampoline code just below. */ + if (TARGET_ARM) + fprintf (f, "\t.arm\n"); + else if (TARGET_THUMB2) + fprintf (f, "\t.thumb\n"); + else + /* Only ARM and Thumb-2 are supported. */ + gcc_assert ( !TARGET_ARM && !TARGET_THUMB2); + + assemble_aligned_integer (UNITS_PER_WORD, const0_rtx); + assemble_aligned_integer (UNITS_PER_WORD, const0_rtx); + /* Trampoline code which sets the static chain register but also + PIC register before jumping into real code. */ + asm_fprintf (f, "\tldr\t%r, [%r, #%d]\n", + STATIC_CHAIN_REGNUM, PC_REGNUM, + TARGET_THUMB2 ? 8 : 4); + asm_fprintf (f, "\tldr\t%r, [%r, #%d]\n", + PIC_OFFSET_TABLE_REGNUM, PC_REGNUM, + TARGET_THUMB2 ? 8 : 4); + asm_fprintf (f, "\tldr\t%r, [%r, #%d]\n", + PC_REGNUM, PC_REGNUM, + TARGET_THUMB2 ? 8 : 4); + assemble_aligned_integer (UNITS_PER_WORD, const0_rtx); + } + else if (TARGET_ARM) { fprintf (f, "\t.arm\n"); asm_fprintf (f, "\tldr\t%r, [%r, #0]\n", STATIC_CHAIN_REGNUM, PC_REGNUM); @@ -3997,12 +4034,37 @@ arm_trampoline_init (rtx m_tramp, tree fndecl, rtx chain_value) emit_block_move (m_tramp, assemble_trampoline_template (), GEN_INT (TRAMPOLINE_SIZE), BLOCK_OP_NORMAL); - mem = adjust_address (m_tramp, SImode, TARGET_32BIT ? 8 : 12); - emit_move_insn (mem, chain_value); + if (TARGET_FDPIC) + { + rtx funcdesc = XEXP (DECL_RTL (fndecl), 0); + rtx fnaddr = gen_rtx_MEM (Pmode, funcdesc); + rtx gotaddr = gen_rtx_MEM (Pmode, plus_constant (Pmode, funcdesc, 4)); + rtx trampoline_code_start + = plus_constant (Pmode, XEXP (m_tramp, 0), TARGET_THUMB2 ? 9 : 8); + + /* Write initial funcdesc which points to the trampoline. */ + mem = adjust_address (m_tramp, SImode, 0); + emit_move_insn (mem, trampoline_code_start); + mem = adjust_address (m_tramp, SImode, 4); + emit_move_insn (mem, gen_rtx_REG (Pmode, PIC_OFFSET_TABLE_REGNUM)); + /* Setup static chain. */ + mem = adjust_address (m_tramp, SImode, 20); + emit_move_insn (mem, chain_value); + /* GOT + real function entry point. */ + mem = adjust_address (m_tramp, SImode, 24); + emit_move_insn (mem, gotaddr); + mem = adjust_address (m_tramp, SImode, 28); + emit_move_insn (mem, fnaddr); + } + else + { + mem = adjust_address (m_tramp, SImode, TARGET_32BIT ? 8 : 12); + emit_move_insn (mem, chain_value); - mem = adjust_address (m_tramp, SImode, TARGET_32BIT ? 12 : 16); - fnaddr = XEXP (DECL_RTL (fndecl), 0); - emit_move_insn (mem, fnaddr); + mem = adjust_address (m_tramp, SImode, TARGET_32BIT ? 12 : 16); + fnaddr = XEXP (DECL_RTL (fndecl), 0); + emit_move_insn (mem, fnaddr); + } a_tramp = XEXP (m_tramp, 0); emit_library_call (gen_rtx_SYMBOL_REF (Pmode, "__clear_cache"), @@ -4016,7 +4078,9 @@ arm_trampoline_init (rtx m_tramp, tree fndecl, rtx chain_value) static rtx arm_trampoline_adjust_address (rtx addr) { - if (TARGET_THUMB) + /* For FDPIC don't fix trampoline address since it's a function + descriptor and not a function address. */ + if (TARGET_THUMB && !TARGET_FDPIC) addr = expand_simple_binop (Pmode, IOR, addr, const1_rtx, NULL, 0, OPTAB_LIB_WIDEN); return addr; diff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h index 4671d64..22a65a1 100644 --- a/gcc/config/arm/arm.h +++ b/gcc/config/arm/arm.h @@ -1581,7 +1581,7 @@ typedef struct #define INIT_EXPANDERS arm_init_expanders () /* Length in units of the trampoline for entering a nested function. */ -#define TRAMPOLINE_SIZE (TARGET_32BIT ? 16 : 20) +#define TRAMPOLINE_SIZE (TARGET_FDPIC ? 32 : (TARGET_32BIT ? 16 : 20)) /* Alignment required for a trampoline in bits. */ #define TRAMPOLINE_ALIGNMENT 32
From: Christophe Lyon <christophe.lyon@linaro.org> In FDPIC mode, the trampoline generated to support pointers to nested functions looks like: .word trampoline address .word trampoline GOT address ldr r12, [pc, #8] ldr r9, [pc, #8] ldr pc, [pc] .word static chain value .word GOT address .word function's address because in FDPIC function pointers are actually pointers to function descriptors, we have to actually generate a function descriptor for the trampoline. 2018-XX-XX Christophe Lyon <christophe.lyon@st.com> Mickaël Guêné <mickael.guene@st.com> gcc/ * config/arm/arm.c (arm_asm_trampoline_template): Add FDPIC support. (arm_trampoline_init): Likewise. (arm_trampoline_init): Likewise. * config/arm/arm.h (TRAMPOLINE_SIZE): Likewise. Change-Id: I4b5127261a9aefa0f0318f110574ec07a856aeb1 -- 2.6.3