[PATCH 2/2] powerpc/trace: Update syscall name matching logic to account for ppc_ prefix

[Naveen N. Rao]

Some syscall entry functions on powerpc are prefixed with
ppc_/ppc32_/ppc64_ rather than the usual sys_/__se_sys prefix. fork(),
clone(), swapcontext() are some examples of syscalls with such entry
points. We need to match against these names when initializing ftrace
syscall tracing.

Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
---
Tracing fork() and clone() was working so far since those had "ppc_" 
prefix and we were jumping past the initial 3 characters to account for 
"SyS_" prefix. We were not enabling tracing for ppc32_/ppc64_ prefixed 
syscall entry points so far.

- Naveen

 arch/powerpc/include/asm/ftrace.h | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index 731cb4314a42..331b17b2e46e 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -67,13 +67,30 @@ struct dyn_arch_ftrace {
 #endif
 
 #if defined(CONFIG_FTRACE_SYSCALLS) && !defined(__ASSEMBLY__)
-#ifdef PPC64_ELF_ABI_v1
+/*
+ * Some syscall entry functions on powerpc start with "ppc_" (fork and clone,
+ * for instance) or ppc32_/ppc64_. We should also match the sys_ variant with
+ * those.
+ */
 #define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
+#ifdef PPC64_ELF_ABI_v1
 static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
 {
 	/* We need to skip past the initial dot, and the __se_sys alias */
 	return !strcmp(sym + 1, name) ||
-		(!strncmp(sym, ".__se_sys", 9) && !strcmp(sym + 6, name));
+		(!strncmp(sym, ".__se_sys", 9) && !strcmp(sym + 6, name)) ||
+		(!strncmp(sym, ".ppc_", 5) && !strcmp(sym + 5, name + 4)) ||
+		(!strncmp(sym, ".ppc32_", 7) && !strcmp(sym + 7, name + 4)) ||
+		(!strncmp(sym, ".ppc64_", 7) && !strcmp(sym + 7, name + 4));
+}
+#else
+static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
+{
+	return !strcmp(sym, name) ||
+		(!strncmp(sym, "__se_sys", 8) && !strcmp(sym + 5, name)) ||
+		(!strncmp(sym, "ppc_", 4) && !strcmp(sym + 4, name + 4)) ||
+		(!strncmp(sym, "ppc32_", 6) && !strcmp(sym + 6, name + 4)) ||
+		(!strncmp(sym, "ppc64_", 6) && !strcmp(sym + 6, name + 4));
 }
 #endif
 #endif /* CONFIG_FTRACE_SYSCALLS && !__ASSEMBLY__ */
-- 
2.17.0