From dfad3d598c4bbbaf137588e22bac1ce624529f7e Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 12 Apr 2011 18:53:25 -0400 Subject: 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 Link: http://lkml.kernel.org/r/20110421023738.476989377@goodmis.org Signed-off-by: Steven Rostedt --- scripts/recordmcount.h | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) (limited to 'scripts/recordmcount.h') 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) { -- cgit v1.2.3