Hi Masami,
On Wed, Nov 28, 2018 at 01:29:45AM +0900, Masami Hiramatsu wrote:
Since commit 4378a7d4be30 ("arm64: implement syscall wrappers") introduced "__arm64_" prefix to all syscall wrapper symbols in sys_call_table, syscall tracer can not find corresponding metadata from syscall name. In the result, we have no syscall ftrace events on arm64 kernel, and some bpf testcases are failed on arm64.
To fix this issue, this introduces custom arch_syscall_match_sym_name() which skips first 8 bytes when comparing the syscall and symbol names.
Fixes: 4378a7d4be30 ("arm64: implement syscall wrappers") Reported-by: Naresh Kamboju naresh.kamboju@linaro.org Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Cc: stable@vger.kernel.org
arch/arm64/include/asm/ftrace.h | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index caa955f10e19..a710f79db442 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -56,6 +56,15 @@ static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs) { return is_compat_task(); }
+#define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
+static inline bool arch_syscall_match_sym_name(const char *sym,
const char *name)+{
- /* Since all syscall functions have __arm64_ prefix, we must skip it */
- return !strcmp(sym + 8, name);
+}
This looks fine to me, but I'm curious about whether this is supposed to work with compat syscalls as well, where the prefix is "__arm64_compat_".
If we broadly follow the x86 lead, we'd have:
return (!strncmp(sym, "__arm64_", 8) && !strcmp(sym + 8, name)) || (!strncmp(sym, "__arm64_compat_", 15) && !strcmp(sym + 15, name));
Do we need to handle compat (i.e. 32-bit) tasks here?
Will