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Message-ID: <d2adb98b53978f1ec5895f94e1cd69ea7245ab82.1592510545.git.mhelsley@vmware.com>
Date: Thu, 18 Jun 2020 13:37:56 -0700
From: Matt Helsley <mhelsley@...are.com>
To: <linux-kernel@...r.kernel.org>
CC: Josh Poimboeuf <jpoimboe@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
Julien Thierry <jthierry@...hat.com>,
Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
Matt Helsley <mhelsley@...are.com>
Subject: [RFC][PATCH v5 10/51] objtool: mcount: Walk objtool Elf structs in find_secsym_ndx
Rather than using indices into raw ELF32/64 tables mapped for the
wrapper, use the objtool functions to find the suitable symbol
in the given text section. This also removes all callers to
find_symtab() and get_symindex() so we can remove them as well.
Also take advantage of this commit to rename the function to
something that reads more easily.
Signed-off-by: Matt Helsley <mhelsley@...are.com>
---
tools/objtool/recordmcount.c | 2 +
tools/objtool/recordmcount.h | 94 ++++++++----------------------------
2 files changed, 22 insertions(+), 74 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index f20582ac99e2..843027a46e1b 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -422,6 +422,8 @@ static int is_mcounted_section_name(char const *const txtname)
strcmp(".cpuidle.text", txtname) == 0;
}
+static const unsigned int missing_sym = (unsigned int)-1;
+
/* 32 bit and 64 bit are very similar */
#include "recordmcount.h"
#define RECORD_MCOUNT_64
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 30f8913aa841..b10f7fcd33c3 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -24,15 +24,13 @@
#undef mcount_adjust
#undef sift_rel_mcount
#undef nop_mcount
-#undef find_secsym_ndx
+#undef find_section_sym_index
#undef has_rel_mcount
#undef tot_relsize
#undef get_mcountsym
-#undef find_symtab
#undef get_shnum
#undef set_shnum
#undef get_shstrndx
-#undef get_symindex
#undef get_sym_str_and_relp
#undef do_func
#undef Elf_Addr
@@ -58,14 +56,12 @@
# define append_func append64
# define sift_rel_mcount sift64_rel_mcount
# define nop_mcount nop_mcount_64
-# define find_secsym_ndx find64_secsym_ndx
+# define find_section_sym_index find64_section_sym_index
# define has_rel_mcount has64_rel_mcount
# define tot_relsize tot64_relsize
-# define find_symtab find_symtab64
# define get_shnum get_shnum64
# define set_shnum set_shnum64
# define get_shstrndx get_shstrndx64
-# define get_symindex get_symindex64
# define get_sym_str_and_relp get_sym_str_and_relp_64
# define do_func do64
# define get_mcountsym get_mcountsym_64
@@ -95,14 +91,12 @@
# define append_func append32
# define sift_rel_mcount sift32_rel_mcount
# define nop_mcount nop_mcount_32
-# define find_secsym_ndx find32_secsym_ndx
+# define find_section_sym_index find32_section_sym_index
# define has_rel_mcount has32_rel_mcount
# define tot_relsize tot32_relsize
-# define find_symtab find_symtab32
# define get_shnum get_shnum32
# define set_shnum set_shnum32
# define get_shstrndx get_shstrndx32
-# define get_symindex get_symindex32
# define get_sym_str_and_relp get_sym_str_and_relp_32
# define do_func do32
# define get_mcountsym get_mcountsym_32
@@ -185,21 +179,6 @@ static int MIPS_is_fake_mcount(Elf_Rel const *rp)
return is_fake;
}
-static unsigned int get_symindex(Elf_Sym const *sym, Elf32_Word const *symtab,
- Elf32_Word const *symtab_shndx)
-{
- unsigned long offset;
- int index;
-
- if (sym->st_shndx != SHN_XINDEX)
- return w2(sym->st_shndx);
-
- offset = (unsigned long)sym - (unsigned long)symtab;
- index = offset / sizeof(*sym);
-
- return w(symtab_shndx[index]);
-}
-
static unsigned int get_shnum(Elf_Ehdr const *ehdr, Elf_Shdr const *shdr0)
{
if (shdr0 && !ehdr->e_shnum)
@@ -225,28 +204,6 @@ static int get_shstrndx(Elf_Ehdr const *ehdr, Elf_Shdr const *shdr0)
return w(shdr0->sh_link);
}
-static void find_symtab(Elf_Ehdr *const ehdr, Elf_Shdr const *shdr0,
- Elf32_Word **symtab,
- Elf32_Word **symtab_shndx)
-{
- unsigned const nhdr = get_shnum(ehdr, shdr0);
- Elf_Shdr const *relhdr;
- unsigned k;
-
- *symtab = NULL;
- *symtab_shndx = NULL;
-
- for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
- if (relhdr->sh_type == SHT_SYMTAB)
- *symtab = (void *)ehdr + relhdr->sh_offset;
- else if (relhdr->sh_type == SHT_SYMTAB_SHNDX)
- *symtab_shndx = (void *)ehdr + relhdr->sh_offset;
-
- if (*symtab && *symtab_shndx)
- break;
- }
-}
-
/* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
static int append_func(Elf_Ehdr *const ehdr,
Elf_Shdr *const shstr,
@@ -507,40 +464,37 @@ static int nop_mcount(const struct section * const rels,
* Num: Value Size Type Bind Vis Ndx Name
* 2: 00000000 0 SECTION LOCAL DEFAULT 1
*/
-static int find_secsym_ndx(unsigned const txtndx,
+static int find_section_sym_index(unsigned const txtndx,
char const *const txtname,
uint_t *const recvalp,
unsigned int *sym_index,
- Elf_Shdr const *const symhdr,
- Elf32_Word const *symtab,
- Elf32_Word const *symtab_shndx,
Elf_Ehdr const *const ehdr)
{
- Elf_Sym const *const sym0 = (Elf_Sym const *)(_w(symhdr->sh_offset)
- + (void *)ehdr);
- unsigned const nsym = _w(symhdr->sh_size) / _w(symhdr->sh_entsize);
- Elf_Sym const *symp;
- unsigned t;
+ struct symbol *sym;
+ struct section *txts = find_section_by_index(lf, txtndx);
- for (symp = sym0, t = nsym; t; --t, ++symp) {
- unsigned int const st_bind = ELF_ST_BIND(symp->st_info);
+ if (!txts) {
+ fprintf(stderr, "Cannot find section %u: %s.\n",
+ txtndx, txtname);
+ return missing_sym;
+ }
- if (txtndx == get_symindex(symp, symtab, symtab_shndx)
- /* avoid STB_WEAK */
- && (STB_LOCAL == st_bind || STB_GLOBAL == st_bind)) {
+ list_for_each_entry(sym, &txts->symbol_list, list) {
+ /* avoid symbols with weak binding */
+ if ((sym->bind == STB_LOCAL) || (sym->bind == STB_GLOBAL)) {
/* function symbols on ARM have quirks, avoid them */
if (w2(ehdr->e_machine) == EM_ARM
- && ELF_ST_TYPE(symp->st_info) == STT_FUNC)
+ && sym->type == STT_FUNC)
continue;
- *recvalp = _w(symp->st_value);
- *sym_index = symp - sym0;
+ *recvalp = sym->sym.st_value;
+ *sym_index = sym->idx;
return 0;
}
}
fprintf(stderr, "Cannot find symbol for section %u: %s.\n",
txtndx, txtname);
- return -1;
+ return missing_sym;
}
static char const *has_rel_mcount(const struct section * const rels)
@@ -577,9 +531,6 @@ static int do_func(Elf_Ehdr *const ehdr,
Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+ (void *)ehdr);
- Elf32_Word *symtab;
- Elf32_Word *symtab_shndx;
-
/* Upper bound on space: assume all relevant relocs are for mcount. */
unsigned totrelsz;
@@ -615,8 +566,6 @@ static int do_func(Elf_Ehdr *const ehdr,
return -1;
}
- find_symtab(ehdr, shdr0, &symtab, &symtab_shndx);
-
list_for_each_entry(sec, &lf->sections, list) {
char const *txtname;
@@ -626,11 +575,8 @@ static int do_func(Elf_Ehdr *const ehdr,
uint_t recval = 0;
symsec_sh_link = sec->sh.sh_link;
- result = find_secsym_ndx(sec->sh.sh_info, txtname,
- &recval, &recsym,
- &shdr0[symsec_sh_link],
- symtab, symtab_shndx,
- ehdr);
+ result = find_section_sym_index(sec->sh.sh_info,
+ txtname, &recval, &recsym, ehdr);
if (result)
goto out;
--
2.20.1
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