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Message-ID: <CAHVXubgTkoWYEybsbXVbCMO4JaMAChaSq4BgqZZO9ih7OxwUyA@mail.gmail.com>
Date: Tue, 3 Oct 2023 20:27:12 +0200
From: Alexandre Ghiti <alexghiti@...osinc.com>
To: Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Sami Tolvanen <samitolvanen@...gle.com>,
Kees Cook <keescook@...omium.org>,
linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
linux-riscv@...ts.infradead.org, Conor Dooley <conor@...nel.org>,
Conor Dooley <conor.dooley@...rochip.com>
Subject: Re: [PATCH -fixes] riscv: Fix ftrace syscall handling which are now
prefixed with __riscv_
@Conor Dooley This fails checkpatch but the documentation here states
that this is how to do:
https://elixir.bootlin.com/linux/latest/source/Documentation/trace/ftrace-design.rst#L246
On Tue, Oct 3, 2023 at 8:24 PM Alexandre Ghiti <alexghiti@...osinc.com> wrote:
>
> ftrace creates entries for each syscall in the tracefs but has failed
> since commit 08d0ce30e0e4 ("riscv: Implement syscall wrappers") which
> prefixes all riscv syscalls with __riscv_.
>
> So fix this by implementing arch_syscall_match_sym_name() which allows us
> to ignore this prefix.
>
> And also ignore compat syscalls like x86/arm64 by implementing
> arch_trace_is_compat_syscall().
>
> Fixes: 08d0ce30e0e4 ("riscv: Implement syscall wrappers")
> Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
> ---
> arch/riscv/include/asm/ftrace.h | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
> index 740a979171e5..2b2f5df7ef2c 100644
> --- a/arch/riscv/include/asm/ftrace.h
> +++ b/arch/riscv/include/asm/ftrace.h
> @@ -31,6 +31,27 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
> return addr;
> }
>
> +/*
> + * Let's do like x86/arm64 and ignore the compat syscalls.
> + */
> +#define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
> +static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
> +{
> + return is_compat_task();
> +}
> +
> +#define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
> +static inline bool arch_syscall_match_sym_name(const char *sym,
> + const char *name)
> +{
> + /*
> + * Since all syscall functions have __riscv_ prefix, we must skip it.
> + * However, as we described above, we decided to ignore compat
> + * syscalls, so we don't care about __riscv_compat_ prefix here.
> + */
> + return !strcmp(sym + 8, name);
> +}
> +
> struct dyn_arch_ftrace {
> };
> #endif
> --
> 2.39.2
>
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