@@ -60,12 +60,32 @@ extern kprobe_opcode_t optprobe_template_end[];
#ifdef PPC64_ELF_ABI_v2
/* PPC64 ABIv2 needs local entry point */
+#ifdef CONFIG_KPROBES_ON_FTRACE
+/*
+ * Per livepatch.h, ftrace location is always within the first 16 bytes
+ * of a function on powerpc with -mprofile-kernel.
+ */
+#define kprobe_lookup_name(name, addr, offset) \
+{ \
+ addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); \
+ if (addr && !(offset)) { \
+ unsigned long faddr; \
+ faddr = ftrace_location_range((unsigned long)addr, \
+ (unsigned long)addr + 16);\
+ if (faddr) \
+ addr = (kprobe_opcode_t *)faddr; \
+ else \
+ addr = (kprobe_opcode_t *)ppc_function_entry(addr); \
+ } \
+}
+#else
#define kprobe_lookup_name(name, addr, offset) \
{ \
addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); \
if (addr && !(offset)) \
addr = (kprobe_opcode_t *)ppc_function_entry(addr); \
}
+#endif
#elif defined(PPC64_ELF_ABI_v1)
/*
* 64bit powerpc ABIv1 uses function descriptors:
KPROBES_ON_FTRACE avoids much of the overhead with regular kprobes as it eliminates the need for a trap, as well as the need to emulate or single-step instructions. Though OPTPROBES provides us with similar performance, we have limited optprobes trampoline slots. As such, when asked to probe at a function entry, default to using the ftrace infrastructure. With: # cd /sys/kernel/debug/tracing # echo 'p _do_fork' > kprobe_events before patch: # cat ../kprobes/list c0000000000daf08 k _do_fork+0x8 [DISABLED] c000000000044fc0 k kretprobe_trampoline+0x0 [OPTIMIZED] and after patch: # cat ../kprobes/list c0000000000d074c k _do_fork+0xc [DISABLED][FTRACE] c0000000000412b0 k kretprobe_trampoline+0x0 [OPTIMIZED] Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> --- arch/powerpc/include/asm/kprobes.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)