On Thu, 19 Apr 2018 11:54:24 +0900
Namhyung Kim <namhy...@kernel.org> wrote:
> On Wed, Apr 18, 2018 at 07:37:59PM -0500, Kim Phillips wrote:
> > diff --git a/tools/perf/arch/arm64/util/sym-handling.c
> > b/tools/perf/arch/arm64/util/sym-handling.c
> > index 0051b1ee8450..5c4a2e208bbc 100644
> > --- a/tools/perf/arch/arm64/util/sym-handling.c
> > +++ b/tools/perf/arch/arm64/util/sym-handling.c
> > @@ -20,3 +20,16 @@ bool elf__needs_adjust_symbols(GElf_Ehdr ehdr)
> > ehdr.e_type == ET_DYN;
> > }
> > #endif
> > +
> > +const char *arch__normalize_symbol_name(const char *name)
> > +{
> > + /*
> > + * arm64 kernels compensating for a CPU erratum can put up a
> > + * module_emit_adrp_veneer in place of a module_emit_plt_entry
> > + */
> > + if (name && strlen(name) >= 23 &&
> > + !strncmp(name, "module_emit_adrp_veneer", 23))
> > + return "module_emit_plt_entry";
> > +
> > + return name;
> > +}
>
> I don't know it's always preferable or just for the test. It it's the
> latter it may be better to move it to the test code.
AFACT, the veneer is a moniker and doesn't technically exist, and
shouldn't be being looked-up. Both chunks of this diff are needed to
pass perf test 1: this chunk above is because in
arch__normalize_symbol_name(), we squash the perf test 1's "<veneer>
not in *kallsyms*" problem, and in the below chunk, we prevent it
coming up when the test code iterates over the *vmlinux* symbols. I.e.
we need to prevent the veneer from coming up in both kallsyms *and*
vmlinux.
> > diff --git a/tools/perf/tests/vmlinux-kallsyms.c
> > b/tools/perf/tests/vmlinux-kallsyms.c
> > index 1e5adb65632a..07064e76947d 100644
> > --- a/tools/perf/tests/vmlinux-kallsyms.c
> > +++ b/tools/perf/tests/vmlinux-kallsyms.c
> > @@ -163,6 +163,29 @@ int test__vmlinux_matches_kallsyms(struct test *test
> > __maybe_unused, int subtest
> >
> > continue;
> > }
> > + } else if (pair) {
> > + s64 skew = mem_start - UM(pair->start);
> > + struct map *kmap =
> > map_groups__find(&kallsyms.kmaps, type, mem_start);
> > + struct map *vmap = map_groups__find(&vmlinux.kmaps,
> > type, mem_start);
> > +
> > + /*
> > + * arm64 kernels compensating for a CPU erratum can
> > put up a
> > + * module_emit_adrp_veneer in place of a
> > module_emit_plt_entry
> > + */
> > + if (llabs(skew) < page_size)
>
> It seems that we needs to check it's the ARM64 at least. If it's a
OK.
> rare case we might need to add more paranoid checks.
It's certainly rare: Adding the authors of the veneer to cc for
comments:
Will, Ard, how probable are veneer-style symbols such as the
one introduced in commit a257e0257 "arm64/kernel: don't ban ADRP to
work around Cortex-A53 erratum #843419" to happen again in the future?
I would have thought WARNing on within-a-pagesize would be OK,
Namhyung. Are you suggesting checking instead for a hardcoded veneer
symbol string?
Thanks,
Kim
> > + {
> > + pr_debug("NO ERR FOR SKEW %ld: %#" PRIx64
> > ": diff start addr v: %s k: %#" PRIx64 " %s\n",
> > + skew, mem_start, sym->name,
> > UM(pair->start), pair->name);
> > + continue;
> > + }
> > +
> > + pr_debug("ERR : %#" PRIx64 ": diff start addr v: %s
> > k: %#" PRIx64 " %s\n",
> > + mem_start, sym->name, UM(pair->start),
> > pair->name);
> > +
> > + if (kmap && vmap) {
> > + pr_debug(" : map v: %s k: %s\n",
> > + vmap->dso->short_name,
> > kmap->dso->short_name);
> > + }
> > } else
> > pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
> > mem_start, sym->name);
