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>,
Sami Tolvanen <samitolvanen@google.com>,
Julien Thierry <jthierry@redhat.com>,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
Matt Helsley <mhelsley@vmware.com>
Subject: [RFC][PATCH v4 07/32] objtool: mcount: Use libelf for section header names
Date: Tue, 2 Jun 2020 12:50:00 -0700 [thread overview]
Message-ID: <3e757ead75e67e58e07e20528e05512aa63bc6fb.1591125127.git.mhelsley@vmware.com> (raw)
In-Reply-To: <cover.1591125127.git.mhelsley@vmware.com>
Rather than passing in the string table contents as a parameter,
pass in the section index of the string table and rely on libelf
string table accessor functions to look up section names.
Note that modifying the string table with libelf will come later
so append_func() is unchanged.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/elf.c | 3 +-
tools/objtool/elf.h | 1 +
tools/objtool/recordmcount.c | 2 +-
tools/objtool/recordmcount.h | 89 ++++++++++++++----------------------
4 files changed, 37 insertions(+), 58 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 067e2850a116..2e8f5f90e264 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -138,8 +138,7 @@ struct section *find_section_by_name(const struct elf *elf, const char *name)
return NULL;
}
-static struct section *find_section_by_index(struct elf *elf,
- unsigned int idx)
+struct section *find_section_by_index(const struct elf *elf, unsigned int idx)
{
struct section *sec;
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index 78a2db23b8b6..ae82479a8259 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -125,6 +125,7 @@ int elf_write(const struct elf *elf);
void elf_close(struct elf *elf);
struct section *find_section_by_name(const struct elf *elf, const char *name);
+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);
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 9941683b3f60..f20582ac99e2 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -177,7 +177,7 @@ static void *mmap_file(char const *fname)
file_updated = 0;
sb.st_size = 0;
- lf = elf_open_read(fname, O_RDONLY);
+ lf = elf_open_read(fname, O_RDWR);
if (!lf) {
perror(fname);
return NULL;
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 3250a461895d..b487308992ce 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -25,7 +25,6 @@
#undef sift_rel_mcount
#undef nop_mcount
#undef find_secsym_ndx
-#undef __has_rel_mcount
#undef has_rel_mcount
#undef tot_relsize
#undef get_mcountsym
@@ -55,7 +54,6 @@
# define sift_rel_mcount sift64_rel_mcount
# define nop_mcount nop_mcount_64
# define find_secsym_ndx find64_secsym_ndx
-# define __has_rel_mcount __has64_rel_mcount
# define has_rel_mcount has64_rel_mcount
# define tot_relsize tot64_relsize
# define get_sym_str_and_relp get_sym_str_and_relp_64
@@ -88,7 +86,6 @@
# define sift_rel_mcount sift32_rel_mcount
# define nop_mcount nop_mcount_32
# define find_secsym_ndx find32_secsym_ndx
-# define __has_rel_mcount __has32_rel_mcount
# define has_rel_mcount has32_rel_mcount
# define tot_relsize tot32_relsize
# define get_sym_str_and_relp get_sym_str_and_relp_32
@@ -197,6 +194,7 @@ static int append_func(Elf_Ehdr *const ehdr,
shstr->sh_size = _w(t);
shstr->sh_offset = _w(sb.st_size);
+
t += sb.st_size;
t += (_align & -t); /* word-byte align */
new_e_shoff = t;
@@ -260,7 +258,7 @@ static int append_func(Elf_Ehdr *const ehdr,
return -1;
if (uwrite(ehdr, sizeof(*ehdr)) < 0)
return -1;
- return 0;
+ return elf_write(lf);
}
static unsigned get_mcountsym(Elf_Sym const *const sym0,
@@ -285,7 +283,7 @@ static unsigned get_mcountsym(Elf_Sym const *const sym0,
return mcountsym;
}
-static void get_sym_str_and_relp(GElf_Shdr const *const relhdr,
+static void get_sym_str_and_relp(const struct section * const rels,
Elf_Ehdr const *const ehdr,
Elf_Sym const **sym0,
char const **str0,
@@ -293,10 +291,10 @@ static void get_sym_str_and_relp(GElf_Shdr const *const relhdr,
{
Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+ (void *)ehdr);
- unsigned const symsec_sh_link = relhdr->sh_link;
+ 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 *)(relhdr->sh_offset
+ Elf_Rel const *const rel0 = (Elf_Rel const *)(rels->sh.sh_offset
+ (void *)ehdr);
*sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
@@ -316,7 +314,7 @@ static void get_sym_str_and_relp(GElf_Shdr const *const relhdr,
static uint_t *sift_rel_mcount(uint_t *mlocp,
unsigned const offbase,
Elf_Rel **const mrelpp,
- GElf_Shdr const *const relhdr,
+ const struct section * const rels,
Elf_Ehdr const *const ehdr,
unsigned const recsym_index,
uint_t const recval,
@@ -327,12 +325,12 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
Elf_Sym const *sym0;
char const *str0;
Elf_Rel const *relp;
- unsigned int rel_entsize = relhdr->sh_entsize;
- unsigned const nrel = relhdr->sh_size / rel_entsize;
+ 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(relhdr, ehdr, &sym0, &str0, &relp);
+ get_sym_str_and_relp(rels, ehdr, &sym0, &str0, &relp);
for (t = nrel; t; --t) {
if (!mcountsym)
@@ -364,7 +362,7 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
* that are not going to be traced. The mcount calls here will be converted
* into nops.
*/
-static int nop_mcount(GElf_Shdr const *const relhdr,
+static int nop_mcount(const struct section * const rels,
Elf_Ehdr const *const ehdr,
const char *const txtname)
{
@@ -373,14 +371,14 @@ static int nop_mcount(GElf_Shdr const *const relhdr,
Elf_Sym const *sym0;
char const *str0;
Elf_Rel const *relp;
- Elf_Shdr const *const shdr = &shdr0[relhdr->sh_info];
- unsigned int rel_entsize = relhdr->sh_entsize;
- unsigned const nrel = relhdr->sh_size / rel_entsize;
+ Elf_Shdr const *const shdr = &shdr0[rels->sh.sh_info];
+ unsigned rel_entsize = rels->sh.sh_entsize;
+ unsigned const nrel = rels->sh.sh_size / rel_entsize;
unsigned mcountsym = 0;
unsigned t;
int once = 0;
- get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
+ get_sym_str_and_relp(rels, ehdr, &sym0, &str0, &relp);
for (t = nrel; t; --t) {
int ret = -1;
@@ -463,40 +461,27 @@ static int find_secsym_ndx(unsigned const txtndx,
return -1;
}
-/* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
-static char const * __has_rel_mcount(GElf_Shdr const *const relhdr, /* reltype */
- Elf_Shdr const *const shdr0,
- char const *const shstrtab)
+static char const *has_rel_mcount(const struct section * const rels)
{
- /* .sh_info depends on .sh_type == SHT_REL[,A] */
- Elf_Shdr const *const txthdr = &shdr0[relhdr->sh_info];
- char const *const txtname = &shstrtab[w(txthdr->sh_name)];
-
- if (w(txthdr->sh_type) != SHT_PROGBITS ||
- !(_w(txthdr->sh_flags) & SHF_EXECINSTR))
+ const struct section *txts;
+ if (rels->sh.sh_type != SHT_REL && rels->sh.sh_type != SHT_RELA)
return NULL;
- return txtname;
-}
-
-static char const *has_rel_mcount(GElf_Shdr const *const relhdr,
- Elf_Shdr const *const shdr0,
- char const *const shstrtab)
-{
- if (relhdr->sh_type != SHT_REL && relhdr->sh_type != SHT_RELA)
+ txts = find_section_by_index(lf, rels->sh.sh_info);
+ if ((txts->sh.sh_type != SHT_PROGBITS) ||
+ !(txts->sh.sh_flags & SHF_EXECINSTR))
return NULL;
- return __has_rel_mcount(relhdr, shdr0, shstrtab);
+ return txts->name;
}
-static unsigned tot_relsize(Elf_Shdr const *const shdr0,
- const char *const shstrtab)
+static unsigned tot_relsize(void)
{
- struct section *sec;
+ const struct section *sec;
unsigned totrelsz = 0;
char const *txtname;
list_for_each_entry(sec, &lf->sections, list) {
- txtname = has_rel_mcount(&sec->sh, shdr0, shstrtab);
+ txtname = has_rel_mcount(sec);
if (txtname && is_mcounted_section_name(txtname))
totrelsz += sec->sh.sh_size;
}
@@ -510,11 +495,6 @@ static int do_func(Elf_Ehdr *const ehdr,
{
Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+ (void *)ehdr);
- Elf_Shdr *const shstr = &shdr0[w2(ehdr->e_shstrndx)];
- char const *const shstrtab = (char const *)(_w(shstr->sh_offset)
- + (void *)ehdr);
-
- GElf_Shdr const *relhdr;
/* Upper bound on space: assume all relevant relocs are for mcount. */
unsigned totrelsz;
@@ -528,14 +508,14 @@ static int do_func(Elf_Ehdr *const ehdr,
unsigned rel_entsize = 0;
unsigned symsec_sh_link = 0;
- struct section *sec;
+ const struct section *sec;
int result = 0;
if (find_section_by_name(lf, "__mcount_loc") != NULL)
return 0;
- totrelsz = tot_relsize(shdr0, shstrtab);
+ totrelsz = tot_relsize();
if (totrelsz == 0)
return 0;
mrel0 = umalloc(totrelsz);
@@ -554,38 +534,37 @@ static int do_func(Elf_Ehdr *const ehdr,
list_for_each_entry(sec, &lf->sections, list) {
char const *txtname;
- relhdr = &sec->sh;
- txtname = has_rel_mcount(relhdr, shdr0,
- shstrtab);
+ txtname = has_rel_mcount(sec);
if (txtname && is_mcounted_section_name(txtname)) {
unsigned int recsym;
uint_t recval = 0;
- symsec_sh_link = relhdr->sh_link;
- result = find_secsym_ndx(relhdr->sh_info, txtname,
+ symsec_sh_link = sec->sh.sh_link;
+ result = find_secsym_ndx(sec->sh.sh_info, txtname,
&recval, &recsym,
&shdr0[symsec_sh_link],
ehdr);
if (result)
goto out;
- rel_entsize = relhdr->sh_entsize;
+ rel_entsize = sec->sh.sh_entsize;
mlocp = sift_rel_mcount(mlocp,
(void *)mlocp - (void *)mloc0, &mrelp,
- relhdr, ehdr, recsym, recval, reltype);
+ sec, ehdr, recsym, recval, reltype);
} 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.
*/
- if (nop_mcount(relhdr, ehdr, txtname) < 0) {
+ if (nop_mcount(sec, ehdr, txtname) < 0) {
result = -1;
goto out;
}
}
}
if (!result && mloc0 != mlocp)
- result = append_func(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,
+ result = append_func(ehdr, &shdr0[w2(ehdr->e_shstrndx)],
+ mloc0, mlocp, mrel0, mrelp,
rel_entsize, symsec_sh_link);
out:
free(mrel0);
--
2.20.1
next prev parent reply other threads:[~2020-06-02 19:52 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 01/32] objtool: Prepare to merge recordmcount Matt Helsley
2020-06-09 8:54 ` Julien Thierry
2020-06-09 15:42 ` Matt Helsley
2020-06-09 19:31 ` Julien Thierry
2020-06-02 19:49 ` [RFC][PATCH v4 02/32] objtool: Make recordmcount into mcount subcmd Matt Helsley
2020-06-09 9:00 ` Julien Thierry
2020-06-09 18:39 ` Matt Helsley
2020-06-09 18:52 ` Steven Rostedt
2020-06-09 18:56 ` Matt Helsley
2020-06-09 19:11 ` Julien Thierry
2020-06-02 19:49 ` [RFC][PATCH v4 03/32] objtool: recordmcount: Start using objtool's elf wrapper Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 04/32] objtool: recordmcount: Search for __mcount_loc before walking the sections Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 05/32] objtool: recordmcount: Convert do_func() relhdrs Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 06/32] objtool: mcount: Remove unused fname parameter Matt Helsley
2020-06-02 19:50 ` Matt Helsley [this message]
2020-06-02 19:50 ` [RFC][PATCH v4 08/32] objtool: mcount: Walk objtool Elf structs in find_secsym_ndx Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 09/32] objtool: mcount: Use symbol structs to find mcount relocations Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 10/32] objtool: mcount: Walk relocation lists Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 11/32] objtool: mcount: Move get_mcountsym Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 12/32] objtool: mcount: Replace MIPS offset types Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 13/32] objtool: mcount: Move is_fake_mcount() Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 14/32] objtool: mcount: Stop using ehdr in find_section_sym_index Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 15/32] objtool: mcount: Move find_section_sym_index() Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 16/32] objtool: mcount: Restrict using ehdr in append_func() Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 17/32] objtool: mcount: Use objtool ELF to write Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount() Matt Helsley
2020-06-12 13:26 ` Peter Zijlstra
2020-06-12 16:05 ` Peter Zijlstra
2020-06-17 17:36 ` Matt Helsley
2020-06-17 18:30 ` Peter Zijlstra
2020-06-13 19:49 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 19/32] objtool: mcount: Move has_rel_mcount() and tot_relsize() Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 20/32] objtool: mcount: Move relocation entry size detection Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 21/32] objtool: mcount: Only keep ELF file size Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 22/32] objtool: mcount: Use ELF header from objtool Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 23/32] objtool: mcount: Remove unused file mapping Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 24/32] objtool: mcount: Reduce usage of _size wrapper Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 25/32] objtool: mcount: Move mcount_adjust out of wrapper Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 26/32] objtool: mcount: Pre-allocate new ELF sections Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 27/32] objtool: mcount: Generic location and relocation table types Matt Helsley
2020-06-09 6:41 ` Kamalesh Babulal
2020-06-09 18:12 ` Matt Helsley
2020-06-10 4:35 ` Kamalesh Babulal
2020-06-02 19:50 ` [RFC][PATCH v4 28/32] objtool: mcount: Move sift_rel_mcount out of wrapper file Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 29/32] objtool: mcount: Remove wrapper for ELF relocation type Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 30/32] objtool: mcount: Remove wrapper double-include trick Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 31/32] objtool: mcount: Remove endian wrappers Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 32/32] objtool: mcount: Rename Matt Helsley
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