Re: [GCC][PATCH 13/15, v6] arm: Add support for dwarf debug directives and pseudo hard-register for PAC feature.

[Richard Earnshaw via Gcc-patches]

On 18/01/2023 17:18, Srinath Parvathaneni via Gcc-patches wrote:

Hello,

This patch teaches the DWARF support in gcc about RA_AUTH_CODE pseudo 
hard-register and also
updates the ".save", ".cfi_register", ".cfi_offset", ".cfi_restore" directives 
accordingly.
This patch also adds support to emit ".pacspval" directive when "pac ip, lr, 
sp" instruction
in generated in the assembly.

RA_AUTH_CODE register number is 107 and it's dwarf register number is 143.

Applying this patch on top of PACBTI series posted here
https://gcc.gnu.org/pipermail/gcc-patches/2022-August/599658.html and when 
compiling the following
test.c with "-march=armv8.1-m.main+mve+pacbti -mbranch-protection=pac-ret 
-mthumb -mfloat-abi=hard
fasynchronous-unwind-tables -g -O0 -S" command line options, the assembly 
output after this patch
looks like below:

$cat test.c

void fun1(int a);
void fun(int a,...)
{
   fun1(a);
}

int main()
{
   fun (10);
   return 0;
}

$ arm-none-eabi-gcc -march=armv8.1-m.main+mve+pacbti 
-mbranch-protection=pac-ret -mthumb -mfloat-abi=hard
-fasynchronous-unwind-tables -g -O0 -S test.s

Assembly output:
...
fun:
...
 .pacspval
 pac ip, lr, sp
 .cfi_register 143, 12
 push{r3, r7, ip, lr}
 .save {r3, r7, ra_auth_code, lr}
...
 .cfi_offset 143, -24
...
 .cfi_restore 143
...
 aut ip, lr, sp
 bx  lr
...
main:
...
 .pacspval
 pac ip, lr, sp
 .cfi_register 143, 12
 push{r3, r7, ip, lr}
 .save {r3, r7, ra_auth_code, lr}
...
 .cfi_offset 143, -8
...
 .cfi_restore 143
...
 aut ip, lr, sp
 bx  lr
...

Regression tested on arm-none-eabi target and found no regressions.

Ok for master?

Regards,
Srinath.

2023-01-18  Srinath Parvathaneni  

 * config/arm/aout.h (ra_auth_code): Add entry in enum.
 (emit_multi_reg_push): Add RA_AUTH_CODE register to
 dwarf frame expression.
 (arm_emit_multi_reg_pop): Restore RA_AUTH_CODE register.
 (arm_expand_prologue): Update frame related information and reg notes
 for pac/pacbit insn.
 (arm_regno_class): Check for pac pseudo reigster.
 (arm_dbx_register_number): Assign ra_auth_code register number in 
dwarf.
 (arm_init_machine_status): Set pacspval_needed to zero.
 (arm_debugger_regno): Check for PAC register.
 (arm_unwind_emit_sequence): Print .save directive with ra_auth_code
 register.
 (arm_unwind_emit_set): Add entry for IP_REGNUM in switch case.
 (arm_unwind_emit): Update REG_CFA_REGISTER case._
 * config/arm/arm.h (FIRST_PSEUDO_REGISTER): Modify.
 (DWARF_PAC_REGNUM): Define.
 (IS_PAC_REGNUM): Likewise.
 (enum reg_class): Add PAC_REG entry.
 (machine_function): Add pacbti_needed state to structure.
 * config/arm/arm.md (RA_AUTH_CODE): Define.

gcc/testsuite/ChangeLog:

2023-01-18  Srinath Parvathaneni  

 * g++.target/arm/pac-1.C: New test.
 * gcc.target/arm/pac-15.c: Likewise.


OK.

R.

[GCC][PATCH 13/15, v6] arm: Add support for dwarf debug directives and pseudo hard-register for PAC feature.

[Srinath Parvathaneni via Gcc-patches]

Hello,

This patch teaches the DWARF support in gcc about RA_AUTH_CODE pseudo 
hard-register and also 
updates the ".save", ".cfi_register", ".cfi_offset", ".cfi_restore" directives 
accordingly.
This patch also adds support to emit ".pacspval" directive when "pac ip, lr, 
sp" instruction
in generated in the assembly.

RA_AUTH_CODE register number is 107 and it's dwarf register number is 143.

Applying this patch on top of PACBTI series posted here
https://gcc.gnu.org/pipermail/gcc-patches/2022-August/599658.html and when 
compiling the following
test.c with "-march=armv8.1-m.main+mve+pacbti -mbranch-protection=pac-ret 
-mthumb -mfloat-abi=hard
fasynchronous-unwind-tables -g -O0 -S" command line options, the assembly 
output after this patch
looks like below:

$cat test.c

void fun1(int a);
void fun(int a,...)
{
  fun1(a);
}

int main()
{
  fun (10);
  return 0;
}

$ arm-none-eabi-gcc -march=armv8.1-m.main+mve+pacbti 
-mbranch-protection=pac-ret -mthumb -mfloat-abi=hard
-fasynchronous-unwind-tables -g -O0 -S test.s

Assembly output:
...
fun:
...
.pacspval
pac ip, lr, sp
.cfi_register 143, 12
push{r3, r7, ip, lr}
.save {r3, r7, ra_auth_code, lr}
...
.cfi_offset 143, -24
...
.cfi_restore 143
...
aut ip, lr, sp
bx  lr
...
main:
...
.pacspval
pac ip, lr, sp
.cfi_register 143, 12
push{r3, r7, ip, lr}
.save {r3, r7, ra_auth_code, lr}
...
.cfi_offset 143, -8
...
.cfi_restore 143
...
aut ip, lr, sp
bx  lr
...

Regression tested on arm-none-eabi target and found no regressions.

Ok for master?

Regards,
Srinath.

2023-01-18  Srinath Parvathaneni  

* config/arm/aout.h (ra_auth_code): Add entry in enum.
(emit_multi_reg_push): Add RA_AUTH_CODE register to
dwarf frame expression.
(arm_emit_multi_reg_pop): Restore RA_AUTH_CODE register.
(arm_expand_prologue): Update frame related information and reg notes
for pac/pacbit insn.
(arm_regno_class): Check for pac pseudo reigster.
(arm_dbx_register_number): Assign ra_auth_code register number in dwarf.
(arm_init_machine_status): Set pacspval_needed to zero.
(arm_debugger_regno): Check for PAC register.
(arm_unwind_emit_sequence): Print .save directive with ra_auth_code
register.
(arm_unwind_emit_set): Add entry for IP_REGNUM in switch case.
(arm_unwind_emit): Update REG_CFA_REGISTER case._
* config/arm/arm.h (FIRST_PSEUDO_REGISTER): Modify.
(DWARF_PAC_REGNUM): Define.
(IS_PAC_REGNUM): Likewise.
(enum reg_class): Add PAC_REG entry.
(machine_function): Add pacbti_needed state to structure.
* config/arm/arm.md (RA_AUTH_CODE): Define.

gcc/testsuite/ChangeLog:

2023-01-18  Srinath Parvathaneni  

* g++.target/arm/pac-1.C: New test.
* gcc.target/arm/pac-15.c: Likewise.


pacbti_dwarf.patch
Description: pacbti_dwarf.patch