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-rw-r--r--Documentation/trace/ftrace-design.txt4
-rw-r--r--kernel/trace/trace_syscalls.c21
2 files changed, 18 insertions, 7 deletions
diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
index 6fca17beee2f..79fcafc7fd64 100644
--- a/Documentation/trace/ftrace-design.txt
+++ b/Documentation/trace/ftrace-design.txt
@@ -250,6 +250,10 @@ You need very few things to get the syscalls tracing in an arch.
250- If the system call table on this arch is more complicated than a simple array 250- If the system call table on this arch is more complicated than a simple array
251 of addresses of the system calls, implement an arch_syscall_addr to return 251 of addresses of the system calls, implement an arch_syscall_addr to return
252 the address of a given system call. 252 the address of a given system call.
253- If the symbol names of the system calls do not match the function names on
254 this arch, define ARCH_HAS_SYSCALL_MATCH_SYM_NAME in asm/ftrace.h and
255 implement arch_syscall_match_sym_name with the appropriate logic to return
256 true if the function name corresponds with the symbol name.
253- Tag this arch as HAVE_SYSCALL_TRACEPOINTS. 257- Tag this arch as HAVE_SYSCALL_TRACEPOINTS.
254 258
255 259
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index af831545f656..86a23e7de031 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -60,6 +60,19 @@ extern struct syscall_metadata *__stop_syscalls_metadata[];
60 60
61static struct syscall_metadata **syscalls_metadata; 61static struct syscall_metadata **syscalls_metadata;
62 62
63#ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
64static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
65{
66 /*
67 * Only compare after the "sys" prefix. Archs that use
68 * syscall wrappers may have syscalls symbols aliases prefixed
69 * with "SyS" instead of "sys", leading to an unwanted
70 * mismatch.
71 */
72 return !strcmp(sym + 3, name + 3);
73}
74#endif
75
63static __init struct syscall_metadata * 76static __init struct syscall_metadata *
64find_syscall_meta(unsigned long syscall) 77find_syscall_meta(unsigned long syscall)
65{ 78{
@@ -73,13 +86,7 @@ find_syscall_meta(unsigned long syscall)
73 kallsyms_lookup(syscall, NULL, NULL, NULL, str); 86 kallsyms_lookup(syscall, NULL, NULL, NULL, str);
74 87
75 for ( ; start < stop; start++) { 88 for ( ; start < stop; start++) {
76 /* 89 if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name))
77 * Only compare after the "sys" prefix. Archs that use
78 * syscall wrappers may have syscalls symbols aliases prefixed
79 * with "SyS" instead of "sys", leading to an unwanted
80 * mismatch.
81 */
82 if ((*start)->name && !strcmp((*start)->name + 3, str + 3))
83 return *start; 90 return *start;
84 } 91 }
85 return NULL; 92 return NULL;