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Message-ID: <20210319014246.c6trc4x3qewro32c@treble>
Date: Thu, 18 Mar 2021 20:42:46 -0500
From: Josh Poimboeuf <jpoimboe@...hat.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: x86@...nel.org, jgross@...e.com, mbenes@...e.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 08/14] objtool: Add elf_create_reloc() helper
On Thu, Mar 18, 2021 at 06:11:11PM +0100, Peter Zijlstra wrote:
> We have 4 instances of adding a relocation. Create a common helper
> to avoid growing even more.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
I'm not a fan of the API -- how about squashing this in? Untested, of
course.
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 6a52d56504b1..38ffa3b2595e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -469,12 +469,11 @@ static int create_static_call_sections(struct objtool_file *file)
memset(site, 0, sizeof(struct static_call_site));
/* populate reloc for 'addr' */
- if (!elf_create_reloc(file->elf, sec, idx * sizeof(struct static_call_site),
- R_X86_64_PC32,
- reloc_to_insn, insn, 0)) {
- WARN_ELF("elf_create_reloc: static_call_site::addr");
+ if (elf_add_reloc_to_insn(file->elf, sec,
+ idx * sizeof(struct static_call_site),
+ R_X86_64_PC32,
+ insn->sec, insn->offset))
return -1;
- }
/* find key symbol */
key_name = strdup(insn->call_dest->name);
@@ -511,13 +510,11 @@ static int create_static_call_sections(struct objtool_file *file)
free(key_name);
/* populate reloc for 'key' */
- if (!elf_create_reloc(file->elf, sec, idx * sizeof(struct static_call_site) + 4,
- R_X86_64_PC32,
- reloc_to_sym, key_sym,
- is_sibling_call(insn) * STATIC_CALL_SITE_TAIL)) {
- WARN_ELF("elf_create_reloc: static_call_site::key");
+ if (elf_add_reloc(file->elf, sec,
+ idx * sizeof(struct static_call_site) + 4,
+ R_X86_64_PC32, key_sym,
+ is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
return -1;
- }
idx++;
}
@@ -559,12 +556,11 @@ static int create_mcount_loc_sections(struct objtool_file *file)
loc = (unsigned long *)sec->data->d_buf + idx;
memset(loc, 0, sizeof(unsigned long));
- if (!elf_create_reloc(file->elf, sec, idx * sizeof(unsigned long),
- R_X86_64_64,
- reloc_to_insn, insn, 0)) {
- WARN_ELF("elf_create_reloc: __mcount_loc");
+ if (elf_add_reloc_to_insn(file->elf, sec,
+ idx * sizeof(unsigned long),
+ R_X86_64_64,
+ insn->sec, insn->offset))
return -1;
- }
idx++;
}
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index d2afe2454de4..b3bd97b2b034 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -447,76 +447,73 @@ static int read_symbols(struct elf *elf)
return -1;
}
-static void elf_add_reloc(struct elf *elf, struct reloc *reloc)
+int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
+ unsigned int type, struct symbol *sym, int addend)
{
- struct section *sec = reloc->sec;
+ struct reloc *reloc;
+
+ reloc = malloc(sizeof(*reloc));
+ if (!reloc) {
+ perror("malloc");
+ return -1;
+ }
+ memset(reloc, 0, sizeof(*reloc));
+
+ reloc->sec = sec->reloc;
+ reloc->offset = offset;
+ reloc->type = type;
+ reloc->sym = sym;
+ reloc->addend = addend;
list_add_tail(&reloc->list, &sec->reloc_list);
elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));
- sec->changed = true;
-}
-
-void reloc_to_sym(struct reloc *reloc, void *dst)
-{
- struct symbol *sym = dst;
- reloc->sym = sym;
+ return 0;
}
-void __reloc_to_insn(struct reloc *reloc, struct section *sec, unsigned long offset)
+static int insn_to_sym_addend(struct section *sec, unsigned long offset,
+ struct symbol **sym, int *addend)
{
if (sec->sym) {
- reloc->sym = sec->sym;
- reloc->addend = offset;
- return;
+ *sym = sec->sym;
+ *addend = offset;
+ return 0;
}
/*
* The Clang assembler strips section symbols, so we have to reference
* the function symbol instead:
*/
- reloc->sym = find_symbol_containing(sec, offset);
- if (!reloc->sym) {
+ *sym = find_symbol_containing(sec, offset);
+ if (!*sym) {
/*
* Hack alert. This happens when we need to reference the NOP
* pad insn immediately after the function.
*/
- reloc->sym = find_symbol_containing(sec, offset - 1);
+ *sym = find_symbol_containing(sec, offset - 1);
}
- if (reloc->sym)
- reloc->addend = offset - reloc->sym->offset;
-}
-
-struct reloc *elf_create_reloc(struct elf *elf,
- struct section *sec, unsigned long offset,
- unsigned int type,
- void (*set_dest)(struct reloc *, void *), void *dst, int addend)
-{
- struct reloc *reloc;
-
- reloc = malloc(sizeof(*reloc));
- if (!reloc) {
- perror("malloc");
- return NULL;
+ if (!*sym) {
+ WARN("can't find symbol containing %s+0x%lx", sec->name, offset);
+ return -1;
}
- memset(reloc, 0, sizeof(*reloc));
- reloc->sec = sec->reloc;
- reloc->offset = offset;
- reloc->type = type;
+ *addend = offset - (*sym)->offset;
+ return 0;
+}
- set_dest(reloc, dst);
- if (!reloc->sym) {
- WARN("failed to create reloc");
- return NULL;
- }
- reloc->addend += addend;
+int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
+ unsigned long offset, unsigned int type,
+ struct section *insn_sec, unsigned long insn_off)
+{
+ struct symbol *sym;
+ int addend;
- elf_add_reloc(elf, reloc);
+ if (insn_to_sym_addend(insn_sec, insn_off, &sym, &addend))
+ return -1;
- return reloc;
+ return elf_add_reloc(elf, sec, offset, type, sym, addend);
}
static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 8f31f96c8fe1..f5be798107bc 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -9,7 +9,6 @@
#include <stdbool.h>
#include <objtool/cfi.h>
#include <objtool/arch.h>
-#include <objtool/elf.h>
struct insn_state {
struct cfi_state cfi;
@@ -92,10 +91,4 @@ struct instruction *find_insn(struct objtool_file *file,
insn->sec == sec; \
insn = list_next_entry(insn, list))
-static inline void reloc_to_insn(struct reloc *reloc, void *dst)
-{
- struct instruction *insn = dst;
- __reloc_to_insn(reloc, insn->sec, insn->offset);
-}
-
#endif /* _CHECK_H */
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 8b11f3cdad98..825ad326201d 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -124,13 +124,11 @@ struct elf *elf_open_read(const char *name, int flags);
struct section *elf_create_section(struct elf *elf, const char *name, unsigned int sh_flags, size_t entsize, int nr);
struct section *elf_create_reloc_section(struct elf *elf, struct section *base, int reltype);
-void reloc_to_sym(struct reloc *reloc, void *sym);
-void __reloc_to_insn(struct reloc *reloc, struct section *sec, unsigned long offset);
-
-struct reloc *elf_create_reloc(struct elf *elf,
- struct section *sec, unsigned long offset,
- unsigned int type,
- void (*set_dest)(struct reloc *reloc, void *), void *dst, int addend);
+int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
+ unsigned int type, struct symbol *sym, int addend);
+int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
+ unsigned long offset, unsigned int type,
+ struct section *insn_sec, unsigned long insn_off);
int elf_write_insn(struct elf *elf, struct section *sec,
unsigned long offset, unsigned int len,
@@ -148,8 +146,6 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, uns
struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
unsigned long offset, unsigned int len);
struct symbol *find_func_containing(struct section *sec, unsigned long offset);
-void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset,
- struct reloc *reloc);
#define for_each_sec(file, sec) \
list_for_each_entry(sec, &file->elf->sections, list)
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index dfc3cc6ef4aa..1b57be6508f4 100644
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -81,24 +81,11 @@ static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi)
return 0;
}
-struct orc_list_entry {
- struct list_head list;
- struct orc_entry orc;
- struct section *insn_sec;
- unsigned long insn_off;
-};
-
-static void reloc_to_orc(struct reloc *reloc, void *dst)
-{
- struct orc_list_entry *entry = dst;
- __reloc_to_insn(reloc, entry->insn_sec, entry->insn_off);
-}
-
static int write_orc_entry(struct elf *elf, struct section *orc_sec,
struct section *ip_sec, unsigned int idx,
- struct orc_list_entry *entry)
+ struct section *insn_sec, unsigned long insn_off,
+ struct orc_entry *o)
{
- struct orc_entry *o = &entry->orc;
struct orc_entry *orc;
/* populate ORC data */
@@ -108,16 +95,20 @@ static int write_orc_entry(struct elf *elf, struct section *orc_sec,
orc->bp_offset = bswap_if_needed(orc->bp_offset);
/* populate reloc for ip */
- if (!elf_create_reloc(elf, ip_sec, idx * sizeof(int),
- R_X86_64_PC32,
- reloc_to_orc, entry, 0)) {
- WARN_ELF("elf_create_reloc: ORC ip");
+ if (elf_add_reloc_to_insn(elf, ip_sec, idx * sizeof(int), R_X86_64_PC32,
+ insn_sec, insn_off))
return -1;
- }
return 0;
}
+struct orc_list_entry {
+ struct list_head list;
+ struct orc_entry orc;
+ struct section *insn_sec;
+ unsigned long insn_off;
+};
+
static int orc_list_add(struct list_head *orc_list, struct orc_entry *orc,
struct section *sec, unsigned long offset)
{
@@ -239,7 +230,9 @@ int orc_create(struct objtool_file *file)
/* Write ORC entries to sections: */
list_for_each_entry(entry, &orc_list, list) {
- if (write_orc_entry(file->elf, orc_sec, sec, idx++, entry))
+ if (write_orc_entry(file->elf, orc_sec, sec, idx++,
+ entry->insn_sec, entry->insn_off,
+ &entry->orc))
return -1;
}
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