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tracing/syscalls: Allow arch specific syscall symbol matching 

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 moves the match logic out into a separate function which an
arch can override by defining ARCH_HAS_SYSCALL_MATCH_SYM_NAME in
asm/ftrace.h and implementing arch_syscall_match_sym_name.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
LKML-Reference: <1296703645-18718-5-git-send-email-imunsie@au1.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Ian Munsie 2011-02-03 14:27:23 +11:00 committed by Steven Rostedt
parent c763ba06bd
commit b2d5549681
2 changed files with 18 additions and 7 deletions
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4
Documentation/trace/ftrace-design.txt
View File

@ -250,6 +250,10 @@ 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, define ARCH_HAS_SYSCALL_MATCH_SYM_NAME in asm/ftrace.h and
implement 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.

21
kernel/trace/trace_syscalls.c
View File

@ -60,6 +60,19 @@ extern struct syscall_metadata *__stop_syscalls_metadata[];
static struct syscall_metadata **syscalls_metadata;
#ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
static inline bool 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);
}
#endif
static __init struct syscall_metadata *
find_syscall_meta(unsigned long syscall)
{
@ -73,13 +86,7 @@ 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;