Re: [PATCH v17 07/16] tracing: Add ftrace_fill_perf_regs() for perf event

[Will Deacon <will@kernel.org>]

On Wed, Oct 16, 2024 at 09:59:12AM +0900, Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> 
> Add ftrace_fill_perf_regs() which should be compatible with the
> perf_fetch_caller_regs(). In other words, the pt_regs returned from the
> ftrace_fill_perf_regs() must satisfy 'user_mode(regs) == false' and can be
> used for stack tracing.
> 
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Nicholas Piggin <npiggin@gmail.com>
> Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
> Cc: Naveen N Rao <naveen@kernel.org>
> Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
> Cc: Heiko Carstens <hca@linux.ibm.com>
> Cc: Vasily Gorbik <gor@linux.ibm.com>
> Cc: Alexander Gordeev <agordeev@linux.ibm.com>
> Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
> Cc: Sven Schnelle <svens@linux.ibm.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: x86@kernel.org
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> 
> ---
>   Changes in v16:
>    - Fix s390 to clear psw.mask according to Heiko's suggestion.
> ---
>  arch/arm64/include/asm/ftrace.h   |    7 +++++++
>  arch/powerpc/include/asm/ftrace.h |    7 +++++++
>  arch/s390/include/asm/ftrace.h    |    6 ++++++
>  arch/x86/include/asm/ftrace.h     |    7 +++++++
>  include/linux/ftrace.h            |   31 +++++++++++++++++++++++++++++++
>  5 files changed, 58 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
> index d344c69eb01e..6493a575664f 100644
> --- a/arch/arm64/include/asm/ftrace.h
> +++ b/arch/arm64/include/asm/ftrace.h
> @@ -146,6 +146,13 @@ ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
>  	return regs;
>  }
>  
> +#define arch_ftrace_fill_perf_regs(fregs, _regs) do {		\
> +		(_regs)->pc = arch_ftrace_regs(fregs)->pc;			\
> +		(_regs)->regs[29] = arch_ftrace_regs(fregs)->fp;		\
> +		(_regs)->sp = arch_ftrace_regs(fregs)->sp;			\
> +		(_regs)->pstate = PSR_MODE_EL1h;		\
> +	} while (0)

arm64 bit looks correct to me:

Acked-by: Will Deacon <will@kernel.org>

Will