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Date: Thu, 18 Jun 2020 13:37:57 -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 11/51] objtool: mcount: Use symbol structs to find mcount relocations
Rather than open coding symbol name lookups in get_sym_and_*()
we rename the structure and use objtool's lookup function to
get the symbol name for a relocation. We also change the name
of the function to better reflect its purpose.
Signed-off-by: Matt Helsley <mhelsley@...are.com>
---
tools/objtool/elf.c | 2 +-
tools/objtool/elf.h | 1 +
tools/objtool/recordmcount.h | 54 ++++++++++--------------------------
3 files changed, 17 insertions(+), 40 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 17e39b3a1719..8dcdea8020a5 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -196,7 +196,7 @@ struct section *find_section_by_index(const struct elf *elf, unsigned int idx)
return NULL;
}
-static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
+struct symbol *find_symbol_by_index(const struct elf *elf, unsigned int idx)
{
struct symbol *sym;
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index 60eb44661658..09fa0d085341 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -135,6 +135,7 @@ struct section *find_section_by_index(const struct elf *elf, unsigned int idx);
struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
struct symbol *find_symbol_by_name(const struct elf *elf, const char *name);
+struct symbol *find_symbol_by_index(const struct elf *elf, unsigned int idx);
struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset);
struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset);
struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index b10f7fcd33c3..3dae878f11a8 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -31,7 +31,7 @@
#undef get_shnum
#undef set_shnum
#undef get_shstrndx
-#undef get_sym_str_and_relp
+#undef get_relp
#undef do_func
#undef Elf_Addr
#undef Elf_Ehdr
@@ -62,7 +62,7 @@
# define get_shnum get_shnum64
# define set_shnum set_shnum64
# define get_shstrndx get_shstrndx64
-# define get_sym_str_and_relp get_sym_str_and_relp_64
+# define get_relp get_relp_64
# define do_func do64
# define get_mcountsym get_mcountsym_64
# define is_fake_mcount is_fake_mcount64
@@ -97,7 +97,7 @@
# define get_shnum get_shnum32
# define set_shnum set_shnum32
# define get_shstrndx get_shstrndx32
-# define get_sym_str_and_relp get_sym_str_and_relp_32
+# define get_relp get_relp_32
# define do_func do32
# define get_mcountsym get_mcountsym_32
# define is_fake_mcount is_fake_mcount32
@@ -298,15 +298,10 @@ static int append_func(Elf_Ehdr *const ehdr,
return elf_write(lf);
}
-static unsigned get_mcountsym(Elf_Sym const *const sym0,
- Elf_Rel const *relp,
- char const *const str0)
+static unsigned get_mcountsym(Elf_Rel const *relp)
{
- unsigned mcountsym = 0;
-
- Elf_Sym const *const symp =
- &sym0[Elf_r_sym(relp)];
- char const *symname = &str0[w(symp->st_name)];
+ struct symbol *sym = find_symbol_by_index(lf, Elf_r_sym(relp));
+ char const *symname = sym->name;
char const *mcount = gpfx == '_' ? "_mcount" : "mcount";
char const *fentry = "__fentry__";
@@ -315,31 +310,16 @@ static unsigned get_mcountsym(Elf_Sym const *const sym0,
if (strcmp(mcount, symname) == 0 ||
(altmcount && strcmp(altmcount, symname) == 0) ||
(strcmp(fentry, symname) == 0))
- mcountsym = Elf_r_sym(relp);
-
- return mcountsym;
+ return Elf_r_sym(relp);
+ return 0;
}
-static void get_sym_str_and_relp(const struct section * const rels,
- Elf_Ehdr const *const ehdr,
- Elf_Sym const **sym0,
- char const **str0,
- Elf_Rel const **relp)
+static void get_relp(const struct section * const rels,
+ Elf_Ehdr const *const ehdr,
+ Elf_Rel const **relp)
{
- Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
- + (void *)ehdr);
- unsigned const symsec_sh_link = rels->sh.sh_link;
- Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
- Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
Elf_Rel const *const rel0 = (Elf_Rel const *)(rels->sh.sh_offset
+ (void *)ehdr);
-
- *sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
- + (void *)ehdr);
-
- *str0 = (char const *)(_w(strsec->sh_offset)
- + (void *)ehdr);
-
*relp = rel0;
}
@@ -359,19 +339,17 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
{
uint_t *const mloc0 = mlocp;
Elf_Rel *mrelp = *mrelpp;
- Elf_Sym const *sym0;
- char const *str0;
Elf_Rel const *relp;
unsigned int rel_entsize = rels->sh.sh_entsize;
unsigned const nrel = rels->sh.sh_size / rel_entsize;
unsigned mcountsym = 0;
unsigned t;
- get_sym_str_and_relp(rels, ehdr, &sym0, &str0, &relp);
+ get_relp(rels, ehdr, &relp);
for (t = nrel; t; --t) {
if (!mcountsym)
- mcountsym = get_mcountsym(sym0, relp, str0);
+ mcountsym = get_mcountsym(relp);
if (mcountsym && mcountsym == Elf_r_sym(relp) &&
!is_fake_mcount(relp)) {
@@ -405,8 +383,6 @@ static int nop_mcount(const struct section * const rels,
{
Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+ (void *)ehdr);
- Elf_Sym const *sym0;
- char const *str0;
Elf_Rel const *relp;
Elf_Shdr const *const shdr = &shdr0[rels->sh.sh_info];
unsigned rel_entsize = rels->sh.sh_entsize;
@@ -415,13 +391,13 @@ static int nop_mcount(const struct section * const rels,
unsigned t;
int once = 0;
- get_sym_str_and_relp(rels, ehdr, &sym0, &str0, &relp);
+ get_relp(rels, ehdr, &relp);
for (t = nrel; t; --t) {
int ret = -1;
if (!mcountsym)
- mcountsym = get_mcountsym(sym0, relp, str0);
+ mcountsym = get_mcountsym(relp);
if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
if (make_nop)
--
2.20.1
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