@@ -71,12 +71,21 @@ void arch__fix_tev_from_maps(struct perf_probe_event *pev,
struct probe_trace_event *tev, struct map *map)
{
/*
- * ppc64 ABIv2 local entry point is currently always 2 instructions
- * (8 bytes) after the global entry point.
+ * When probing at a function entry point, we normally always want the
+ * LEP since that catches calls to the function through both the GEP and
+ * the LEP. Hence, we would like to probe at an offset of 8 bytes if
+ * the user only specified the function entry.
+ *
+ * However, if the user specifies an offset, we fall back to using the
+ * GEP since all userspace applications (objdump/readelf) show function
+ * disassembly with offsets from the GEP.
+ *
+ * In addition, we shouldn't specify an offset for kretprobes.
*/
- if (!pev->uprobes && map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS) {
- tev->point.address += PPC64LE_LEP_OFFSET;
+ if (pev->point.offset || pev->point.retprobe || !map)
+ return;
+
+ if (map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS)
tev->point.offset += PPC64LE_LEP_OFFSET;
- }
}
#endif
So far, we used to treat probe point offsets as being offset from the LEP. However, userspace applications (objdump/readelf) always show disassembly and offsets from the function GEP. This is confusing to the user as we will end up probing at an address different from what the user expects when looking at the function disassembly with readelf/objdump. Fix this by changing how we modify probe address with perf. If only the function name is provided, we assume the user needs the LEP. Otherwise, if an offset is specified, we assume that the user knows the exact address to probe based on function disassembly, and so we just place the probe from the GEP offset. Finally, kretprobe was also broken with kallsyms as we were trying to specify an offset. This patch also fixes that issue. Cc: Mark Wielaard <mjw@redhat.com> Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Balbir Singh <bsingharora@gmail.com> Reported-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> --- v2: Removed un-necessary check for uprobes tools/perf/arch/powerpc/util/sym-handling.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)