powerpc/ftrace: Implement raw syscall tracepoints on PowerPC
This patch implements the raw syscall tracepoints on PowerPC and exports
them for ftrace syscalls to use.
To minimise reworking existing code, I slightly re-ordered the thread
info flags such that the new TIF_SYSCALL_TRACEPOINT bit would still fit
within the 16 bits of the andi. instruction's UI field. The instructions
in question are in /arch/powerpc/kernel/entry_{32,64}.S to and the
_TIF_SYSCALL_T_OR_A with the thread flags to see if system call tracing
is enabled.
In the case of 64bit PowerPC, arch_syscall_addr and
arch_syscall_match_sym_name are overridden to allow ftrace syscalls to
work given the unusual system call table structure and symbol names that
start with a period.
Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index dde1296..169d039 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -60,4 +60,18 @@
#endif
+#if defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_PPC64) && !defined(__ASSEMBLY__)
+#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);
+}
+#endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_PPC64 && !__ASSEMBLY__ */
+
#endif /* _ASM_POWERPC_FTRACE */
