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| author | Steven Rostedt <srostedt@redhat.com> | 2011-04-12 18:53:25 -0400 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2011-05-16 14:44:20 -0400 |
| commit | dfad3d598c4bbbaf137588e22bac1ce624529f7e (patch) | |
| tree | 7df293e467f93913d1979a0e7131bb6e1977acd7 /scripts/recordmcount.h | |
| parent | ffd618fa39284f8cc343894b566dd42ec6e74e77 (diff) | |
| download | linux-dfad3d598c4bbbaf137588e22bac1ce624529f7e.tar.gz linux-dfad3d598c4bbbaf137588e22bac1ce624529f7e.tar.bz2 linux-dfad3d598c4bbbaf137588e22bac1ce624529f7e.zip | |
ftrace/recordmcount: Add warning logic to warn on mcount not recorded
There's some sections that should not have mcount recorded and should not have
modifications to the that code. But currently they waste some time by calling
mcount anyway (which simply returns). As the real answer should be to
either whitelist the section or have gcc ignore it fully.
This change adds a option to recordmcount to warn when it finds a section
that is ignored by ftrace but still contains mcount callers. This is not on
by default as developers may not know if the section should be completely
ignored or added to the whitelist.
Cc: John Reiser <jreiser@bitwagon.com>
Link: http://lkml.kernel.org/r/20110421023738.476989377@goodmis.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'scripts/recordmcount.h')
| -rw-r--r-- | scripts/recordmcount.h | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h index 657dbedd1c7f..22033d563bcd 100644 --- a/scripts/recordmcount.h +++ b/scripts/recordmcount.h @@ -313,7 +313,8 @@ static uint_t *sift_rel_mcount(uint_t *mlocp, * into nops. */ static void nop_mcount(Elf_Shdr const *const relhdr, - Elf_Ehdr const *const ehdr) + Elf_Ehdr const *const ehdr, + const char *const txtname) { Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff) + (void *)ehdr); @@ -336,6 +337,7 @@ static void nop_mcount(Elf_Shdr const *const relhdr, unsigned mcountsym = 0; unsigned t; + int once = 0; for (t = nrel; t; --t) { int ret = -1; @@ -353,8 +355,18 @@ static void nop_mcount(Elf_Shdr const *const relhdr, mcountsym = Elf_r_sym(relp); } - if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) - ret = make_nop((void *)ehdr, shdr->sh_offset + relp->r_offset); + if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) { + if (make_nop) + ret = make_nop((void *)ehdr, shdr->sh_offset + relp->r_offset); + if (warn_on_notrace_sect && !once) { + printf("Section %s has mcount callers being ignored\n", + txtname); + once = 1; + /* just warn? */ + if (!make_nop) + return; + } + } /* * If we successfully removed the mcount, mark the relocation @@ -501,12 +513,12 @@ do_func(Elf_Ehdr *const ehdr, char const *const fname, unsigned const reltype) mlocp = sift_rel_mcount(mlocp, (void *)mlocp - (void *)mloc0, &mrelp, relhdr, ehdr, recsym, recval, reltype); - } else if (make_nop && txtname) { + } else if (txtname && (warn_on_notrace_sect || make_nop)) { /* * This section is ignored by ftrace, but still * has mcount calls. Convert them to nops now. */ - nop_mcount(relhdr, ehdr); + nop_mcount(relhdr, ehdr, txtname); } } if (mloc0 != mlocp) { |