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SubjectRe: [PATCH] tracing/x86: fix trace event registration for syscalls without arguments
On Mon, 27 Apr 2020 16:16:20 +0300
Konstantin Khlebnikov <khlebnikov@yandex-team.ru> wrote:

> Bump, bug still present in 5.7.0-rc3
>
> root@kernel0:~# uname -r
> 5.7.0-rc3-test
>
> root@kernel0:~# ls -d /sys/kernel/tracing/events/syscalls/sys_enter_{sync,fsync}
> ls: cannot access '/sys/kernel/tracing/events/syscalls/sys_enter_sync': No such file or directory
> /sys/kernel/tracing/events/syscalls/sys_enter_fsync
>
> On 08/04/2020 21.13, Konstantin Khlebnikov wrote:
> > Syscalls without arguments now has no ABI subs, instead of that macro
> > SYSCALL_DEFINE0() defines __abi_sys_name as aliase to __do_sys_name.
> >
> > As a result in find_syscall_meta() kallsyms_lookup() returns
> > "__do_sys_name" which does not match with declared trace event.
> >
> > Also see commit 1c758a2202a6 ("tracing/x86: Update syscall trace events
> > to handle new prefixed syscall func names")

This is the first I've seen of this patch.

> >
> > Fixes: d2b5de495ee9 ("x86/entry: Refactor SYSCALL_DEFINE0 macros")
> > Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
> > ---
> > arch/x86/include/asm/ftrace.h | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
> > index 85be2f506272..70b96cae5b42 100644
> > --- a/arch/x86/include/asm/ftrace.h
> > +++ b/arch/x86/include/asm/ftrace.h
> > @@ -61,11 +61,12 @@ static inline bool arch_syscall_match_sym_name(const char *sym, const char *name
> > {
> > /*
> > * Compare the symbol name with the system call name. Skip the
> > - * "__x64_sys", "__ia32_sys" or simple "sys" prefix.
> > + * "__x64_sys", "__ia32_sys", "__do_sys" or simple "sys" prefix.
> > */
> > return !strcmp(sym + 3, name + 3) ||
> > (!strncmp(sym, "__x64_", 6) && !strcmp(sym + 9, name + 3)) ||
> > - (!strncmp(sym, "__ia32_", 7) && !strcmp(sym + 10, name + 3));
> > + (!strncmp(sym, "__ia32_", 7) && !strcmp(sym + 10, name + 3)) ||
> > + (!strncmp(sym, "__do_sys", 8) && !strcmp(sym + 8, name + 3));
> > }

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve

> >
> > #ifndef COMPILE_OFFSETS
> >

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