| Message ID | 20241010101510.1487477-3-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: stacktrace: improve unwind reporting | expand |
On Thu, Oct 10, 2024 at 11:15:02AM +0100, Mark Rutland wrote: > For historical reasons the layout of struct pt_regs is dependent on the > ocnfigured endianness, with the order of the 'sycallno' and 'unused2' configured Reviewed-by: Mark Brown <broonie@kernel.org>
On Thu, 10 Oct 2024, Mark Brown wrote: > On Thu, Oct 10, 2024 at 11:15:02AM +0100, Mark Rutland wrote: > > > For historical reasons the layout of struct pt_regs is dependent on the > > ocnfigured endianness, with the order of the 'sycallno' and 'unused2' > > configured and 'syscallno' Miroslav
diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h index 10eca3a3fed49..1ae671fe64d86 100644 --- a/arch/arm64/include/asm/ptrace.h +++ b/arch/arm64/include/asm/ptrace.h @@ -162,13 +162,9 @@ struct pt_regs { }; }; u64 orig_x0; -#ifdef __AARCH64EB__ - u32 unused2; s32 syscallno; -#else - s32 syscallno; - u32 unused2; -#endif + u32 unused; + u64 sdei_ttbr1; /* Only valid when ARM64_HAS_GIC_PRIO_MASKING is enabled. */ u64 pmr_save;
For historical reasons the layout of struct pt_regs is dependent on the ocnfigured endianness, with the order of the 'sycallno' and 'unused2' fields varying dependent upon whether __AARCH64EB__ is defined. We no longer depend on the order of these two fields and can remove the ifdeffery. The current conditional layout was introduced in commit: 35d0e6fb4d219d64 ("arm64: syscallno is secretly an int, make it official") At the time, this was necessary so that the entry assembly could use a single STP instruction to save the pt_regs::{orig_x0,syscallno} fields, without logic that was conditional on the endianness of the kernel: | el0_svc_naked: | stp x0, xscno, [sp, #S_ORIG_X0] // save the original x0 and syscall number This logic was converted to C in commit: f37099b6992a0b81 ("arm64: convert syscall trace logic to C") Since that commit, we no longer manipulate pt_regs::orig_x0 from assembly, and only manipulate pt_regs::syscallno as a 32-bit quantity early in the kernel_entry assembly: | /* Not in a syscall by default (el0_svc overwrites for real syscall) */ | .if \el == 0 | mov w21, #NO_SYSCALL | str w21, [sp, #S_SYSCALLNO] | .endif Given the above, there's no longer a need for the layout of pt_regs::{syscallno,unused2} to depend on the endianness of the kernel. This patch removes the ifdeffery and places 'syscallno' before 'unused2' regardless of the endianess of the kernel. At the same time, 'unused2' is renamed to 'unused', as it is the only unused field within pt_regs. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Josh Poimboeuf <jpoimboe@kernel.org> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Brown <broonie@kernel.org> Cc: Miroslav Benes <mbenes@suse.cz> Cc: Puranjay Mohan <puranjay12@gmail.com> Cc: Will Deacon <will@kernel.org> --- arch/arm64/include/asm/ptrace.h | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)