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Message-ID: <311ccd169cec877d0c1993772818f0e5cdf11dc4.1591125127.git.mhelsley@vmware.com>
Date: Tue, 2 Jun 2020 12:50:20 -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>,
Sami Tolvanen <samitolvanen@...gle.com>,
Julien Thierry <jthierry@...hat.com>,
Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
Matt Helsley <mhelsley@...are.com>
Subject: [RFC][PATCH v4 27/32] objtool: mcount: Generic location and relocation table types
Rather than building the exact ELF section data we need and
avoiding libelf's conversion step, use more GElf types
and then libelf's elfxx_xlatetof() functions to convert
the mcount locations (GElf_Addr) and associated relocations.
This converts sift_rel_mcount() so that it doesn't use the
recordmcount wrapper. The next patch will move it out of the
wrapper.
Signed-off-by: Matt Helsley <mhelsley@...are.com>
---
tools/objtool/recordmcount.c | 44 +++----------
tools/objtool/recordmcount.h | 120 ++++++++++++++---------------------
2 files changed, 59 insertions(+), 105 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 06a8f8ddefa7..ef3c360a3db9 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -210,7 +210,7 @@ static int is_mcounted_section_name(char const *const txtname)
strcmp(".cpuidle.text", txtname) == 0;
}
-static unsigned get_mcountsym(struct reloc *reloc)
+static unsigned int get_mcount_sym_info(struct reloc *reloc)
{
struct symbol *sym = reloc->sym;
char const *symname = sym->name;
@@ -321,16 +321,16 @@ static int nop_mcount(struct section * const rels,
{
struct reloc *reloc;
struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
- unsigned mcountsym = 0;
+ unsigned int mcount_sym_info = 0;
int once = 0;
list_for_each_entry(reloc, &rels->reloc_list, list) {
int ret = -1;
- if (!mcountsym)
- mcountsym = get_mcountsym(reloc);
+ if (!mcount_sym_info)
+ mcount_sym_info = get_mcount_sym_info(reloc);
- if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
+ if (mcount_sym_info == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
if (make_nop) {
ret = make_nop(txts, reloc->offset);
if (ret < 0)
@@ -391,6 +391,9 @@ static unsigned tot_relsize(unsigned int *rel_entsize)
*/
static int mcount_adjust = 0;
+/* Size of an entry in __mcount_loc; 4 or 8 */
+static size_t loc_size;
+
/* 32 bit and 64 bit are very similar */
#include "recordmcount.h"
#define RECORD_MCOUNT_64
@@ -408,34 +411,6 @@ static int arm_is_fake_mcount(struct reloc const *rp)
return 1;
}
-/* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
- * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
- * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
- * to imply the order of the members; the spec does not say so.
- * typedef unsigned char Elf64_Byte;
- * fails on MIPS64 because their <elf.h> already has it!
- */
-
-typedef uint8_t myElf64_Byte; /* Type for a 8-bit quantity. */
-
-union mips_r_info {
- Elf64_Xword r_info;
- struct {
- Elf64_Word r_sym; /* Symbol index. */
- myElf64_Byte r_ssym; /* Special symbol. */
- myElf64_Byte r_type3; /* Third relocation. */
- myElf64_Byte r_type2; /* Second relocation. */
- myElf64_Byte r_type; /* First relocation. */
- } r_mips;
-};
-
-static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
-{
- rp->r_info = ((union mips_r_info){
- .r_mips = { .r_sym = w(sym), .r_type = type }
- }).r_info;
-}
-
static int do_file(char const *const fname)
{
unsigned int reltype = 0;
@@ -551,6 +526,7 @@ static int do_file(char const *const fname)
reltype = R_MIPS_32;
is_fake_mcount = MIPS_is_fake_mcount;
}
+ loc_size = 4;
rc = do32(reltype);
break;
case ELFCLASS64: {
@@ -566,9 +542,9 @@ static int do_file(char const *const fname)
}
if (lf->ehdr.e_machine == EM_MIPS) {
reltype = R_MIPS_64;
- Elf64_r_info = MIPS64_r_info;
is_fake_mcount = MIPS_is_fake_mcount;
}
+ loc_size = 8;
rc = do64(reltype);
break;
}
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index de31ff003032..b58f0cc58f76 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -19,86 +19,63 @@
*/
#undef sift_rel_mcount
#undef do_func
-#undef Elf_Shdr
-#undef Elf_Rel
#undef Elf_Rela
-#undef ELF_R_INFO
-#undef Elf_r_info
-#undef fn_ELF_R_INFO
-#undef uint_t
-#undef _w
-#undef _size
#ifdef RECORD_MCOUNT_64
# define sift_rel_mcount sift64_rel_mcount
# define do_func do64
-# define Elf_Rel Elf64_Rel
# define Elf_Rela Elf64_Rela
-# define ELF_R_INFO ELF64_R_INFO
-# define Elf_r_info Elf64_r_info
-# define fn_ELF_R_INFO fn_ELF64_R_INFO
-# define uint_t uint64_t
-# define _w w8
-# define _size 8
#else
# define sift_rel_mcount sift32_rel_mcount
# define do_func do32
-# define Elf_Rel Elf32_Rel
# define Elf_Rela Elf32_Rela
-# define ELF_R_INFO ELF32_R_INFO
-# define Elf_r_info Elf32_r_info
-# define fn_ELF_R_INFO fn_ELF32_R_INFO
-# define uint_t uint32_t
-# define _w w
-# define _size 4
#endif
-static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
-{
- rp->r_info = _w(ELF_R_INFO(sym, type));
-}
-static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
-
/*
* Look at the relocations in order to find the calls to mcount.
* Accumulate the section offsets that are found, and their relocation info,
* onto the end of the existing arrays.
*/
-static uint_t *sift_rel_mcount(uint_t *mlocp,
- unsigned const offbase,
- Elf_Rel **const mrelpp,
+static void sift_rel_mcount(GElf_Addr **mlocpp,
+ GElf_Sxword *r_offsetp,
+ void **const mrelpp,
const struct section * const rels,
unsigned const recsym_index,
unsigned long const recval,
- unsigned const reltype)
+ unsigned const reltype,
+ bool is_rela)
{
- uint_t *const mloc0 = mlocp;
- Elf_Rel *mrelp = *mrelpp;
- unsigned int rel_entsize = rels->sh.sh_entsize;
- unsigned mcountsym = 0;
+ GElf_Rel *mrelp = *mrelpp;
+ GElf_Rela *mrelap = *mrelpp;
+ unsigned int mcount_sym_info = 0;
struct reloc *reloc;
list_for_each_entry(reloc, &rels->reloc_list, list) {
- if (!mcountsym)
- mcountsym = get_mcountsym(reloc);
-
- if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
- uint_t const addend =
- _w(reloc->offset - recval + mcount_adjust);
- mrelp->r_offset = _w(offbase
- + ((void *)mlocp - (void *)mloc0));
- Elf_r_info(mrelp, recsym_index, reltype);
- if (rel_entsize == sizeof(Elf_Rela)) {
- ((Elf_Rela *)mrelp)->r_addend = addend;
- *mlocp++ = 0;
- } else
- *mlocp++ = addend;
-
- mrelp = (Elf_Rel *)(rel_entsize + (void *)mrelp);
+ unsigned long addend;
+
+ if (!mcount_sym_info)
+ mcount_sym_info = get_mcount_sym_info(reloc);
+
+ if (mcount_sym_info != GELF_R_INFO(reloc->sym->idx, reloc->type) || is_fake_mcount(reloc))
+ continue;
+
+ addend = reloc->offset - recval + mcount_adjust;
+ if (is_rela) {
+ mrelap->r_offset = *r_offsetp;
+ mrelap->r_info = GELF_R_INFO(recsym_index, reltype);
+ mrelap->r_addend = addend;
+ mrelap++;
+ **mlocpp = 0;
+ } else {
+ mrelp->r_offset = *r_offsetp;
+ mrelp->r_info = GELF_R_INFO(recsym_index, reltype);
+ mrelp++;
+ **mlocpp = addend;
}
+ (*mlocpp)++;
+ r_offsetp += loc_size;
}
- *mrelpp = mrelp;
- return mlocp;
+ *mrelpp = is_rela ? (void *)mrelap : (void *)mrelp;
}
@@ -108,11 +85,12 @@ static int do_func(unsigned const reltype)
/* Upper bound on space: assume all relevant relocs are for mcount. */
unsigned totrelsz;
- Elf_Rel * mrel0;
- Elf_Rel * mrelp;
+ void *mrel0;
+ void *mrelp;
- uint_t * mloc0;
- uint_t * mlocp;
+ GElf_Addr *mloc0;
+ GElf_Addr *mlocp;
+ GElf_Sxword r_offset = 0;
unsigned int rel_entsize = 0;
@@ -149,25 +127,28 @@ static int do_func(unsigned const reltype)
: ".rel__mcount_loc";
/* add section: __mcount_loc */
- mlocs = elf_create_section(lf, mc_name + (is_rela ? 1 : 0) + strlen(".rel"), _size, 0);
+ mlocs = elf_create_section(lf, mc_name + (is_rela ? 1 : 0) + strlen(".rel"), sizeof(*mloc0), 0);
if (!mlocs)
goto out;
mlocs->sh.sh_link = 0;
mlocs->sh.sh_info = 0;
- mlocs->sh.sh_addralign = _size;
+ mlocs->sh.sh_addralign = 8;
+ mlocs->data->d_buf = mloc0;
+ mlocs->data->d_type = ELF_T_ADDR; /* elf_xlatetof() conversion */
/* add section .rel[a]__mcount_loc */
mrels = elf_create_section(lf, mc_name, rel_entsize, 0);
if (!mrels)
goto out;
- mrels->sh.sh_type = is_rela
- ? SHT_RELA
- : SHT_REL;
+ /* Like elf_create_rela_section() without the name bits */
+ mrels->sh.sh_type = is_rela ? SHT_RELA : SHT_REL;
mrels->sh.sh_flags = 0;
mrels->sh.sh_link = find_section_by_name(lf, ".symtab")->idx;
mrels->sh.sh_info = old_shnum;
- mrels->sh.sh_addralign = _size;
+ mrels->sh.sh_addralign = 8;
+ mrels->data->d_buf = mrel0;
+ mrels->data->d_type = is_rela ? ELF_T_RELA : ELF_T_REL; /* elf_xlatetof() conversion */
list_for_each_entry(sec, &lf->sections, list) {
char const *txtname;
@@ -181,9 +162,8 @@ static int do_func(unsigned const reltype)
txtname, &recval, &recsym))
goto out;
- mlocp = sift_rel_mcount(mlocp,
- (void *)mlocp - (void *)mloc0, &mrelp,
- sec, recsym, (uint_t)recval, reltype);
+ sift_rel_mcount(&mlocp, &r_offset, &mrelp, sec,
+ recsym, recval, reltype, is_rela);
} else if (txtname && (warn_on_notrace_sect || make_nop)) {
/*
* This section is ignored by ftrace, but still
@@ -195,16 +175,14 @@ static int do_func(unsigned const reltype)
}
if (mloc0 != mlocp) {
- /* Update the section sizes */
+ /* Update the section size and Elf_Data size */
mlocs->sh.sh_size = (void *)mlocp - (void *)mloc0;
mlocs->len = mlocs->sh.sh_size;
mlocs->data->d_size = mlocs->len;
- mlocs->data->d_buf = mloc0;
- mrels->sh.sh_size = (void *)mrelp - (void *)mrel0;
+ mrels->sh.sh_size = mrelp - mrel0;
mrels->len = mrels->sh.sh_size;
mrels->data->d_size = mrels->len;
- mrels->data->d_buf = mrel0;
/* overwrite the ELF file */
result = elf_write(lf);
--
2.20.1
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