Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A198C54EAA for ; Fri, 27 Jan 2023 17:03:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234707AbjA0RDY (ORCPT ); Fri, 27 Jan 2023 12:03:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234850AbjA0RDS (ORCPT ); Fri, 27 Jan 2023 12:03:18 -0500 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE40B13D6F; Fri, 27 Jan 2023 09:02:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1674838977; x=1706374977; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=MSYyxIYpIcGvKGW9ILNeoVixG2YK5UrzbYtuW8oYj7s=; b=fqMX2uUHpvSHI3LmvXlkiuv1CP6y4gq1AAyaNAnb7+HOaex5GEXekKlh 7PXuSDhVi+Mgn0Soa+CaxSsYtqVgUaR8ptmxTplaqP6RllHZiq2bdLith dqVHwRD5OMkJFAdtoovu0TKQ14ez2QBDlSxmr4vwoYf6xqZdWbAJBv+Jn BHYNmNjehASEqx0pvkGm4mxBc8Qnxet8Zq4wh7YU2gDSlpq3hijCuO0Lo ikfnZldjp1uy2rwu2xBiQn1z8hz+xyfH2B5Js2KmjlLphIfRSwdmHHKR6 w6Nxwk/+nJY+yNhCGYt3mFxnl4egAKCcreACXwgcbJ3ULOJYh+ca2xAQy Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10603"; a="310754136" X-IronPort-AV: E=Sophos;i="5.97,251,1669104000"; d="scan'208";a="310754136" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jan 2023 09:02:41 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10603"; a="726739196" X-IronPort-AV: E=Sophos;i="5.97,251,1669104000"; d="scan'208";a="726739196" Received: from ahunter6-mobl1.ger.corp.intel.com (HELO ahunter-VirtualBox.home\044ger.corp.intel.com) ([10.252.57.171]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jan 2023 09:02:39 -0800 From: Adrian Hunter To: Arnaldo Carvalho de Melo Cc: Jiri Olsa , Namhyung Kim , Ian Rogers , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH 3/9] perf symbols: Sort plt relocations for x86 Date: Fri, 27 Jan 2023 19:02:16 +0200 Message-Id: <20230127170222.9895-4-adrian.hunter@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230127170222.9895-1-adrian.hunter@intel.com> References: <20230127170222.9895-1-adrian.hunter@intel.com> MIME-Version: 1.0 Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For x86, with the addition of IFUNCs, relocation information becomes disordered with respect to plt. Correct that by sorting the relocations by offset. Example: Before: $ cat tstpltlib.c void fn1(void) {} void fn2(void) {} void fn3(void) {} void fn4(void) {} $ cat tstpltifunc.c #include void thing1(void) { printf("thing1\n"); } void thing2(void) { printf("thing2\n"); } typedef void (*thing_fn_t)(void); thing_fn_t thing_ifunc(void) { int x; if (x & 1) return thing2; return thing1; } void thing(void) __attribute__ ((ifunc ("thing_ifunc"))); void fn1(void); void fn2(void); void fn3(void); void fn4(void); int main() { fn4(); fn1(); thing(); fn2(); fn3(); return 0; } $ gcc --version gcc (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0 Copyright (C) 2021 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. $ gcc -Wall -Wextra -shared -o libtstpltlib.so tstpltlib.c $ gcc -Wall -Wextra -Wno-uninitialized -o tstpltifunc tstpltifunc.c -L . -ltstpltlib -Wl,-rpath="$(pwd)" $ readelf -rW tstpltifunc | grep -A99 plt Relocation section '.rela.plt' at offset 0x738 contains 8 entries: Offset Info Type Symbol's Value Symbol's Name + Addend 0000000000003f98 0000000300000007 R_X86_64_JUMP_SLOT 0000000000000000 puts@GLIBC_2.2.5 + 0 0000000000003fa8 0000000400000007 R_X86_64_JUMP_SLOT 0000000000000000 __stack_chk_fail@GLIBC_2.4 + 0 0000000000003fb0 0000000500000007 R_X86_64_JUMP_SLOT 0000000000000000 fn1 + 0 0000000000003fb8 0000000600000007 R_X86_64_JUMP_SLOT 0000000000000000 fn3 + 0 0000000000003fc0 0000000800000007 R_X86_64_JUMP_SLOT 0000000000000000 fn4 + 0 0000000000003fc8 0000000900000007 R_X86_64_JUMP_SLOT 0000000000000000 fn2 + 0 0000000000003fd0 0000000b00000007 R_X86_64_JUMP_SLOT 0000000000000000 getrandom@GLIBC_2.25 + 0 0000000000003fa0 0000000000000025 R_X86_64_IRELATIVE 125d $ perf record -e intel_pt//u --filter 'filter main @ ./tstpltifunc' ./tstpltifunc thing2 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.029 MB perf.data ] $ perf script --itrace=be --ns -F+flags,-event,+addr,-period,-comm,-tid,-cpu,-dso 20417.302513948: tr strt 0 [unknown] => 5629a74892be main+0x0 20417.302513948: tr end call 5629a74892c6 main+0x8 => 5629a7489110 fn2@plt+0x0 20417.302513949: tr strt 0 [unknown] => 5629a74892cb main+0xd 20417.302513949: tr end call 5629a74892cb main+0xd => 5629a74890f0 fn3@plt+0x0 20417.302513950: tr strt 0 [unknown] => 5629a74892d0 main+0x12 20417.302513950: tr end call 5629a74892d0 main+0x12 => 5629a74890d0 __stack_chk_fail@plt+0x0 20417.302528114: tr strt 0 [unknown] => 5629a74892d5 main+0x17 20417.302528114: tr end call 5629a74892d5 main+0x17 => 5629a7489120 getrandom@plt+0x0 20417.302528115: tr strt 0 [unknown] => 5629a74892da main+0x1c 20417.302528115: tr end call 5629a74892da main+0x1c => 5629a7489100 fn4@plt+0x0 20417.302528115: tr strt 0 [unknown] => 5629a74892df main+0x21 20417.302528115: tr end return 5629a74892e5 main+0x27 => 7ff14da29d90 __libc_start_call_main+0x80 After: $ perf script --itrace=be --ns -F+flags,-event,+addr,-period,-comm,-tid,-cpu,-dso 20417.302513948: tr strt 0 [unknown] => 5629a74892be main+0x0 20417.302513948: tr end call 5629a74892c6 main+0x8 => 5629a7489110 fn4@plt+0x0 20417.302513949: tr strt 0 [unknown] => 5629a74892cb main+0xd 20417.302513949: tr end call 5629a74892cb main+0xd => 5629a74890f0 fn1@plt+0x0 20417.302513950: tr strt 0 [unknown] => 5629a74892d0 main+0x12 20417.302513950: tr end call 5629a74892d0 main+0x12 => 5629a74890d0 offset_0x10d0@plt+0x0 20417.302528114: tr strt 0 [unknown] => 5629a74892d5 main+0x17 20417.302528114: tr end call 5629a74892d5 main+0x17 => 5629a7489120 fn2@plt+0x0 20417.302528115: tr strt 0 [unknown] => 5629a74892da main+0x1c 20417.302528115: tr end call 5629a74892da main+0x1c => 5629a7489100 fn3@plt+0x0 20417.302528115: tr strt 0 [unknown] => 5629a74892df main+0x21 20417.302528115: tr end return 5629a74892e5 main+0x27 => 7ff14da29d90 __libc_start_call_main+0x80 Signed-off-by: Adrian Hunter --- tools/perf/util/symbol-elf.c | 60 ++++++++++++++++++++++++++++++++++-- 1 file changed, 57 insertions(+), 3 deletions(-) diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index bb1b5cb3ff12..07cfcf8f40e3 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -324,6 +324,8 @@ static char *demangle_sym(struct dso *dso, int kmodule, const char *elf_name) } struct rel_info { + u32 nr_entries; + u32 *sorted; bool is_rela; Elf_Data *reldata; GElf_Rela rela; @@ -332,6 +334,7 @@ struct rel_info { static u32 get_rel_symidx(struct rel_info *ri, u32 idx) { + idx = ri->sorted ? ri->sorted[idx] : idx; if (ri->is_rela) { gelf_getrela(ri->reldata, idx, &ri->rela); return GELF_R_SYM(ri->rela.r_info); @@ -340,6 +343,49 @@ static u32 get_rel_symidx(struct rel_info *ri, u32 idx) return GELF_R_SYM(ri->rel.r_info); } +static u64 get_rel_offset(struct rel_info *ri, u32 x) +{ + if (ri->is_rela) { + GElf_Rela rela; + + gelf_getrela(ri->reldata, x, &rela); + return rela.r_offset; + } else { + GElf_Rel rel; + + gelf_getrel(ri->reldata, x, &rel); + return rel.r_offset; + } +} + +static int rel_cmp(const void *a, const void *b, void *r) +{ + struct rel_info *ri = r; + u64 a_offset = get_rel_offset(ri, *(const u32 *)a); + u64 b_offset = get_rel_offset(ri, *(const u32 *)b); + + return a_offset < b_offset ? -1 : (a_offset > b_offset ? 1 : 0); +} + +static int sort_rel(struct rel_info *ri) +{ + size_t sz = sizeof(ri->sorted[0]); + u32 i; + + ri->sorted = calloc(ri->nr_entries, sz); + if (!ri->sorted) + return -1; + for (i = 0; i < ri->nr_entries; i++) + ri->sorted[i] = i; + qsort_r(ri->sorted, ri->nr_entries, sz, rel_cmp, ri); + return 0; +} + +static void exit_rel(struct rel_info *ri) +{ + free(ri->sorted); +} + static bool get_plt_sizes(struct dso *dso, GElf_Ehdr *ehdr, GElf_Shdr *shdr_plt, u64 *plt_header_size, u64 *plt_entry_size) { @@ -393,7 +439,7 @@ static bool machine_is_x86(GElf_Half e_machine) */ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss) { - uint32_t nr_rel_entries, idx; + uint32_t idx; GElf_Sym sym; u64 plt_offset, plt_header_size, plt_entry_size; GElf_Shdr shdr_plt, plt_sec_shdr; @@ -491,11 +537,18 @@ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss) if (symstrs->d_size == 0) goto out_elf_end; - nr_rel_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize; + ri.nr_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize; ri.is_rela = shdr_rel_plt.sh_type == SHT_RELA; - for (idx = 0; idx < nr_rel_entries; idx++) { + /* + * x86 doesn't insert IFUNC relocations in .plt order, so sort to get + * back in order. + */ + if (machine_is_x86(ehdr.e_machine) && sort_rel(&ri)) + goto out_elf_end; + + for (idx = 0; idx < ri.nr_entries; idx++) { const char *elf_name = NULL; char *demangled = NULL; @@ -523,6 +576,7 @@ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss) err = 0; out_elf_end: + exit_rel(&ri); if (err == 0) return nr; pr_debug("%s: problems reading %s PLT info.\n", -- 2.34.1