From: Ian Munsie <[email protected]>
Some architectures have unusual symbol names and the generic code to
match the symbol name with the function name for the syscall metadata
will fail. For example, symbols on PPC64 start with a period and the
generic code will fail to match them.
This patch splits out the match logic into a standalone weak function
that can be overridden on archs with unusual symbol names.
Signed-off-by: Ian Munsie <[email protected]>
---
Documentation/trace/ftrace-design.txt | 3 +++
include/linux/ftrace.h | 1 +
kernel/trace/trace_syscalls.c | 19 ++++++++++++-------
3 files changed, 16 insertions(+), 7 deletions(-)
diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
index 6fca17b..d996d0a 100644
--- a/Documentation/trace/ftrace-design.txt
+++ b/Documentation/trace/ftrace-design.txt
@@ -250,6 +250,9 @@ You need very few things to get the syscalls tracing in an arch.
- If the system call table on this arch is more complicated than a simple array
of addresses of the system calls, implement an arch_syscall_addr to return
the address of a given system call.
+- If the symbol names of the system calls do not match the function names on
+ this arch, implement an arch_syscall_match_sym_name with the appropriate
+ logic to return true if the function name corresponds with the symbol name.
- Tag this arch as HAVE_SYSCALL_TRACEPOINTS.
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index dcd6a7c..8f6290a 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -527,6 +527,7 @@ extern enum ftrace_dump_mode ftrace_dump_on_oops;
#ifdef CONFIG_FTRACE_SYSCALLS
unsigned long arch_syscall_addr(int nr);
+bool arch_syscall_match_sym_name(const char *sym, const char *name);
#endif /* CONFIG_FTRACE_SYSCALLS */
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index b31ea2d..85983fd 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -81,13 +81,7 @@ static struct syscall_metadata *find_syscall_meta(unsigned long syscall)
kallsyms_lookup(syscall, NULL, NULL, NULL, str);
for ( ; start < stop; start++) {
- /*
- * Only compare after the "sys" prefix. Archs that use
- * syscall wrappers may have syscalls symbols aliases prefixed
- * with "SyS" instead of "sys", leading to an unwanted
- * mismatch.
- */
- if (start->name && !strcmp(start->name + 3, str + 3))
+ if (start->name && arch_syscall_match_sym_name(str, start->name))
return start;
}
return NULL;
@@ -452,6 +446,17 @@ unsigned long __init __weak arch_syscall_addr(int nr)
return (unsigned long)sys_call_table[nr];
}
+bool __weak arch_syscall_match_sym_name(const char *sym, const char *name)
+{
+ /*
+ * Only compare after the "sys" prefix. Archs that use
+ * syscall wrappers may have syscalls symbols aliases prefixed
+ * with "SyS" instead of "sys", leading to an unwanted
+ * mismatch.
+ */
+ return (!strcmp(sym + 3, name + 3));
+}
+
int __init init_ftrace_syscalls(void)
{
struct syscall_metadata *meta;
--
1.7.2.3
On Mon, Dec 6, 2010 at 23:29, Ian Munsie wrote:
> From: Ian Munsie <[email protected]>
>
> Some architectures have unusual symbol names and the generic code to
> match the symbol name with the function name for the syscall metadata
> will fail. For example, symbols on PPC64 start with a period and the
> generic code will fail to match them.
>
> This patch splits out the match logic into a standalone weak function
> that can be overridden on archs with unusual symbol names.
>
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -527,6 +527,7 @@ extern enum ftrace_dump_mode ftrace_dump_on_oops;
> #ifdef CONFIG_FTRACE_SYSCALLS
>
> unsigned long arch_syscall_addr(int nr);
> +bool arch_syscall_match_sym_name(const char *sym, const char *name);
>
> #endif /* CONFIG_FTRACE_SYSCALLS */
>
> --- a/kernel/trace/trace_syscalls.c
> +++ b/kernel/trace/trace_syscalls.c
> @@ -81,13 +81,7 @@ static struct syscall_metadata *find_syscall_meta(unsigned long syscall)
> kallsyms_lookup(syscall, NULL, NULL, NULL, str);
>
> for ( ; start < stop; start++) {
> - /*
> - * Only compare after the "sys" prefix. Archs that use
> - * syscall wrappers may have syscalls symbols aliases prefixed
> - * with "SyS" instead of "sys", leading to an unwanted
> - * mismatch.
> - */
> - if (start->name && !strcmp(start->name + 3, str + 3))
> + if (start->name && arch_syscall_match_sym_name(str, start->name))
> return start;
> }
> return NULL;
> @@ -452,6 +446,17 @@ unsigned long __init __weak arch_syscall_addr(int nr)
> return (unsigned long)sys_call_table[nr];
> }
>
> +bool __weak arch_syscall_match_sym_name(const char *sym, const char *name)
> +{
> + /*
> + * Only compare after the "sys" prefix. Archs that use
> + * syscall wrappers may have syscalls symbols aliases prefixed
> + * with "SyS" instead of "sys", leading to an unwanted
> + * mismatch.
> + */
> + return (!strcmp(sym + 3, name + 3));
> +}
useless set of parenthesis, and this overhead sucks. weak +
additional function call just for a strcmp for most people ? why not
make it into a define in the header:
#ifndef arch_syscall_match_sym_name
#define arch_syscall_match_sym_name(sym, name) !strcmp(sym + 3, name + 3)
#endif
-mike
Excerpts from Mike Frysinger's message of Tue Dec 07 15:56:49 +1100 2010:
> useless set of parenthesis, and this overhead sucks. weak +
> additional function call just for a strcmp for most people ? why not
> make it into a define in the header:
> #ifndef arch_syscall_match_sym_name
> #define arch_syscall_match_sym_name(sym, name) !strcmp(sym + 3, name + 3)
> #endif
> -mike
No problem, will change it.
Cheers,
-Ian
On Tue, 2010-12-07 at 16:06 +1100, Ian Munsie wrote:
> Excerpts from Mike Frysinger's message of Tue Dec 07 15:56:49 +1100 2010:
> > useless set of parenthesis, and this overhead sucks. weak +
> > additional function call just for a strcmp for most people ? why not
> > make it into a define in the header:
> > #ifndef arch_syscall_match_sym_name
> > #define arch_syscall_match_sym_name(sym, name) !strcmp(sym + 3, name + 3)
Make it a static inline function please.
-- Steve
> > #endif
> > -mike
>
> No problem, will change it.
>
> Cheers,
> -Ian