[PATCH 1/2] powerpc/trace elfv1: Update syscall name matching logic

[PATCH 1/2] powerpc/trace elfv1: Update syscall name matching logic

[Naveen N. Rao]

On powerpc64 ABIv1, we are enabling syscall tracing for only ~20
syscalls. This is due to commit e145242ea0df6 ("syscalls/core,
syscalls/x86: Clean up syscall stub naming convention") which has
changed the syscall entry wrapper prefix from "SyS" to "__se_sys".

Update the logic for ABIv1 to not just skip the initial dot, but also
the "__se_sys" prefix.

Fixes: commit e145242ea0df6 ("syscalls/core, syscalls/x86: Clean up syscall stub naming convention")
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/ftrace.h | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index f7a23c2dce74..731cb4314a42 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -71,13 +71,9 @@ struct dyn_arch_ftrace {
 #define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
 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 .sys or .SyS
-	 * prefix from the symbol name and the sys prefix from the system call name and
-	 * just match the rest. This is only needed on ppc64 since symbol names on
-	 * 32bit do not start with a period so the generic function will work.
-	 */
-	return !strcmp(sym + 4, name + 3);
+	/* 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));
 }
 #endif
 #endif /* CONFIG_FTRACE_SYSCALLS && !__ASSEMBLY__ */
-- 
2.17.0

[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@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

Re: [1/2] powerpc/trace elfv1: Update syscall name matching logic

[Michael Ellerman]

On Fri, 2018-05-04 at 13:14:24 UTC, "Naveen N. Rao" wrote:
> On powerpc64 ABIv1, we are enabling syscall tracing for only ~20
> syscalls. This is due to commit e145242ea0df6 ("syscalls/core,
> syscalls/x86: Clean up syscall stub naming convention") which has
> changed the syscall entry wrapper prefix from "SyS" to "__se_sys".
> 
> Update the logic for ABIv1 to not just skip the initial dot, but also
> the "__se_sys" prefix.
> 
> Fixes: commit e145242ea0df6 ("syscalls/core, syscalls/x86: Clean up syscall stub naming convention")
> Reported-by: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>

Series applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/0b7758aaf6543b9a10c8671db559e9

cheers