From: Matt Helsley <mhelsley@vmware.com>
To: <linux-kernel@vger.kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Julien Thierry <jthierry@redhat.com>,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
Matt Helsley <mhelsley@vmware.com>
Subject: [RFC][PATCH v5 42/51] objtool: mcount: Move mcount symbol name testing
Date: Thu, 18 Jun 2020 13:38:28 -0700 [thread overview]
Message-ID: <0a4ae1e3db4f65c8da1988b58e19915e1bf8327d.1592510545.git.mhelsley@vmware.com> (raw)
In-Reply-To: <cover.1592510545.git.mhelsley@vmware.com>
Move the test for mcount symbols into the ELF code itself
and set a class on indicator on the symbol. This simplifies
mcount a little and tests the symbols names near where they're
first touched so should be cache-hot and may also help us
reduce the number of passes through the ELF contents needed
for individual subcommands. Finally, if we manage to combine
subcommands into a single exec of objtool the number of
passes through the ELF data could be even further reduced.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/elf.c | 18 ++++++++++++++++++
tools/objtool/elf.h | 6 ++++++
tools/objtool/mcount.c | 31 +++----------------------------
3 files changed, 27 insertions(+), 28 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 8dcdea8020a5..d55d8fef11b4 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -387,6 +387,21 @@ static int read_sections(struct elf *elf)
return 0;
}
+static bool is_mcount_sym(const char *name)
+{
+ if (name[0] == '.')
+ name++; /* ppc64 hack */
+
+ if (name[0] == '_')
+ name++;
+
+ if (strcmp("mcount", name) == 0 ||
+ (strcmp("__gnu_mcount_nc", name) == 0) ||
+ (strcmp("_fentry__", name) == 0))
+ return true;
+ return false;
+}
+
static int read_symbols(struct elf *elf)
{
struct section *symtab, *symtab_shndx, *sec;
@@ -456,6 +471,9 @@ static int read_symbols(struct elf *elf)
} else
sym->sec = find_section_by_index(elf, 0);
+ if (is_mcount_sym(sym->name))
+ sym->class = SYM_MCOUNT;
+
sym->offset = sym->sym.st_value;
sym->len = sym->sym.st_size;
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index 09fa0d085341..13935edaff54 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -42,6 +42,11 @@ struct section {
bool changed, text, rodata, noinstr;
};
+enum symbol_class {
+ SYM_REGULAR = 0,
+ SYM_MCOUNT = 1,
+};
+
struct symbol {
struct list_head list;
struct rb_node node;
@@ -55,6 +60,7 @@ struct symbol {
unsigned long offset;
unsigned int len;
struct symbol *pfunc, *cfunc, *alias;
+ enum symbol_class class;
bool uaccess_safe;
};
diff --git a/tools/objtool/mcount.c b/tools/objtool/mcount.c
index 029e6e72c972..7fbde6ce6eb8 100644
--- a/tools/objtool/mcount.c
+++ b/tools/objtool/mcount.c
@@ -152,24 +152,6 @@ static int is_mcounted_section_name(char const *const txtname)
strcmp(".cpuidle.text", txtname) == 0;
}
-static struct symbol *get_mcount_sym(struct reloc *reloc)
-{
- struct symbol *sym = reloc->sym;
- char const *symname = sym->name;
-
- if (symname[0] == '.')
- symname++; /* ppc64 hack */
-
- if (symname[0] == '_')
- symname++;
-
- if (strcmp("mcount", symname) == 0 ||
- (strcmp("__gnu_mcount_nc", symname) == 0) ||
- (strcmp("_fentry__", symname) == 0))
- return sym;
- return NULL;
-}
-
/*
* MIPS mcount long call has 2 _mcount symbols, only the position of the 1st
* _mcount symbol is needed for dynamic function tracer, with it, to disable
@@ -266,16 +248,13 @@ static int nop_mcount(struct section * const rels,
{
struct reloc *reloc;
struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
- struct symbol *mcount_sym = NULL;
int once = 0;
list_for_each_entry(reloc, &rels->reloc_list, list) {
int ret = -1;
- if (!mcount_sym)
- mcount_sym = get_mcount_sym(reloc);
-
- if (mcount_sym == reloc->sym && !is_fake_mcount(reloc)) {
+ if (reloc->sym->class == SYM_MCOUNT &&
+ !is_fake_mcount(reloc)) {
if (make_nop) {
ret = make_nop(txts, reloc->offset);
if (ret < 0)
@@ -355,16 +334,12 @@ static void sift_rel_mcount(GElf_Addr **mlocpp,
{
GElf_Rel *mrelp = *mrelpp;
GElf_Rela *mrelap = *mrelpp;
- struct symbol *mcount_sym = NULL;
struct reloc *reloc;
list_for_each_entry(reloc, &rels->reloc_list, list) {
unsigned long addend;
- if (!mcount_sym)
- mcount_sym = get_mcount_sym(reloc);
-
- if (mcount_sym != reloc->sym || is_fake_mcount(reloc))
+ if (reloc->sym->class == SYM_MCOUNT || is_fake_mcount(reloc))
continue;
addend = reloc->offset - recval + mcount_adjust;
--
2.20.1
next prev parent reply other threads:[~2020-06-18 20:41 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-18 20:37 [RFC][PATCH v5 00/51] objtool: Make recordmcount a subcommand Matt Helsley
2020-06-18 20:37 ` [RFC][PATCH v5 01/51] objtool: Factor out reasons to build objtool Matt Helsley
2020-06-24 15:37 ` Miroslav Benes
2020-06-18 20:37 ` [RFC][PATCH v5 02/51] objtool: Prepare to merge recordmcount Matt Helsley
2020-06-18 20:37 ` [RFC][PATCH v5 03/51] objtool: Make recordmcount into mcount subcmd Matt Helsley
2020-06-25 10:39 ` Miroslav Benes
2020-06-18 20:37 ` [RFC][PATCH v5 04/51] objtool: recordmcount: Start using objtool's elf wrapper Matt Helsley
2020-06-18 20:37 ` [RFC][PATCH v5 05/51] objtool: recordmcount: Search for __mcount_loc before walking the sections Matt Helsley
2020-06-18 20:37 ` [RFC][PATCH v5 06/51] objtool: recordmcount: Convert do_func() relhdrs Matt Helsley
2020-06-18 20:37 ` [RFC][PATCH v5 07/51] objtool: mcount: Move nhdr into find_symtab() Matt Helsley
2020-06-18 20:37 ` [RFC][PATCH v5 08/51] objtool: mcount: Remove unused fname parameter Matt Helsley
2020-06-18 20:37 ` [RFC][PATCH v5 09/51] objtool: mcount: Use libelf for section header names Matt Helsley
2020-06-18 20:37 ` [RFC][PATCH v5 10/51] objtool: mcount: Walk objtool Elf structs in find_secsym_ndx Matt Helsley
2020-06-18 20:37 ` [RFC][PATCH v5 11/51] objtool: mcount: Use symbol structs to find mcount relocations Matt Helsley
2020-06-18 20:37 ` [RFC][PATCH v5 12/51] objtool: mcount: Walk relocation lists Matt Helsley
2020-06-18 20:37 ` [RFC][PATCH v5 13/51] objtool: mcount: Return symbol from mcountsym Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 14/51] objtool: mcount: Move get_mcountsym Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 15/51] objtool: mcount: Replace MIPS offset types Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 16/51] objtool: mcount: Move is_fake_mcount() Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 17/51] objtool: mcount: Stop using ehdr in find_section_sym_index Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 18/51] objtool: mcount: Move find_section_sym_index() Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 19/51] objtool: mcount: Restrict using ehdr in append_func() Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 20/51] objtool: mcount: Use objtool ELF to write Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 21/51] objtool: mcount: Move nop_mcount() Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 22/51] objtool: mcount: Move has_rel_mcount() and tot_relsize() Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 23/51] objtool: mcount: Move relocation entry size detection Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 24/51] objtool: mcount: Only keep ELF file size Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 25/51] objtool: mcount: Use ELF header from objtool Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 26/51] objtool: mcount: Remove unused file mapping Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 27/51] objtool: mcount: Reduce usage of _size wrapper Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 28/51] objtool: mcount: Move mcount_adjust out of wrapper Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 29/51] objtool: mcount: Pre-allocate new ELF sections Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 30/51] objtool: mcount: Generic location and relocation table types Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 31/51] objtool: mcount: Use objtool relocation section Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 32/51] objtool: mcount: Move sift_rel_mcount out of wrapper file Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 33/51] objtool: mcount: Remove wrapper for ELF relocation type Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 34/51] objtool: mcount: Remove wrapper double-include trick Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 35/51] objtool: mcount: Remove endian wrappers Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 36/51] objtool: mcount: Rename to mcount.c Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 37/51] objtool: mcount: Simplify mcount name matching Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 38/51] objtool: mcount: mcount symbol name simplification Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 39/51] objtool: mcount: Verify x86 instruction with memcmp() Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 40/51] objtool: mcount: const-ify ARM instruction patterns Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 41/51] objtool: mcount: Convert nop writes to elf_write_insn() Matt Helsley
2020-06-18 20:38 ` Matt Helsley [this message]
2020-06-18 20:38 ` [RFC][PATCH v5 43/51] objtool: check: Use class to recognize kcov calls Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 44/51] objtool: mcount: Keep lists locations and relocations Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 45/51] objtool: mcount: Move mcount section test to objtool ELF Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 46/51] objtool: mcount: Flag mcount relocation sections Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 47/51] objtool: mcount: Merge section mcount flags Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 48/51] objtool: mcount: Eliminate first pass Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 49/51] objtool: mcount: Remove relocation size check Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 50/51] objtool: mcount: Remove useless lookup Matt Helsley
2020-06-18 20:38 ` [RFC][PATCH v5 51/51] objtool: mcount: Remove stale description Matt Helsley
2020-06-23 14:12 ` [RFC][PATCH v5 00/51] objtool: Make recordmcount a subcommand Matt Helsley
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