[PATCH -fixes] riscv: Fix ftrace syscall handling which are now prefixed with __riscv_

[PATCH -fixes] riscv: Fix ftrace syscall handling which are now prefixed with __riscv_

[Alexandre Ghiti]

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@rivosinc.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

Re: [PATCH -fixes] riscv: Fix ftrace syscall handling which are now prefixed with __riscv_

[Alexandre Ghiti]

@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@rivosinc.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@rivosinc.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
>

Re: [PATCH -fixes] riscv: Fix ftrace syscall handling which are now prefixed with __riscv_

[Sami Tolvanen]

On Tue, Oct 3, 2023 at 11:24 AM Alexandre Ghiti <alexghiti@rivosinc.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@rivosinc.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);
> +}

Good catch, thanks for fixing this!

Reviewed-by: Sami Tolvanen <samitolvanen@google.com>

Sami

Re: [PATCH -fixes] riscv: Fix ftrace syscall handling which are now prefixed with __riscv_

[Masami Hiramatsu]

On Tue,  3 Oct 2023 20:24:07 +0200
Alexandre Ghiti <alexghiti@rivosinc.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().
> 

Looks good to me,

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thank you,

> Fixes: 08d0ce30e0e4 ("riscv: Implement syscall wrappers")
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.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
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>

Re: [PATCH -fixes] riscv: Fix ftrace syscall handling which are now prefixed with __riscv_

[Björn Töpel]

Alexandre Ghiti <alexghiti@rivosinc.com> writes:

> @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

FWIW, I'll relax the PW CI checkpatch test going forward. It's way too
strict...

Re: [PATCH -fixes] riscv: Fix ftrace syscall handling which are now prefixed with __riscv_

[Björn Töpel]

Alexandre Ghiti <alexghiti@rivosinc.com> writes:

> 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@rivosinc.com>

This fix does the BPF test suite happier!

Tested-by: Björn Töpel <bjorn@rivosinc.com>

Re: [PATCH -fixes] riscv: Fix ftrace syscall handling which are now prefixed with __riscv_

[patchwork-bot+linux-riscv]

Hello:

This patch was applied to riscv/linux.git (fixes)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Tue,  3 Oct 2023 20:24:07 +0200 you 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.
> 
> [...]

Here is the summary with links:
  - [-fixes] riscv: Fix ftrace syscall handling which are now prefixed with __riscv_
    https://git.kernel.org/riscv/c/a87e7d3e8832

You are awesome, thank you!
-- 
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