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authorLinus Torvalds <torvalds@linux-foundation.org>2020-10-12 13:58:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-12 13:58:15 -0700
commitdd502a81077a5f3b3e19fa9a1accffdcab5ad5bc (patch)
treee993e8d13deadff82ec22d34e68860c71e5443f7 /tools/objtool
parent34eb62d868d729e9a252aa497277081fb652eeed (diff)
parent69e0ad37c9f32d5aa1beb02aab4ec0cd055be013 (diff)
downloadlinux-dd502a81077a5f3b3e19fa9a1accffdcab5ad5bc.tar.bz2
Merge tag 'core-static_call-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull static call support from Ingo Molnar: "This introduces static_call(), which is the idea of static_branch() applied to indirect function calls. Remove a data load (indirection) by modifying the text. They give the flexibility of function pointers, but with better performance. (This is especially important for cases where retpolines would otherwise be used, as retpolines can be pretty slow.) API overview: DECLARE_STATIC_CALL(name, func); DEFINE_STATIC_CALL(name, func); DEFINE_STATIC_CALL_NULL(name, typename); static_call(name)(args...); static_call_cond(name)(args...); static_call_update(name, func); x86 is supported via text patching, otherwise basic indirect calls are used, with function pointers. There's a second variant using inline code patching, inspired by jump-labels, implemented on x86 as well. The new APIs are utilized in the x86 perf code, a heavy user of function pointers, where static calls speed up the PMU handler by 4.2% (!). The generic implementation is not really excercised on other architectures, outside of the trivial test_static_call_init() self-test" * tag 'core-static_call-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits) static_call: Fix return type of static_call_init tracepoint: Fix out of sync data passing by static caller tracepoint: Fix overly long tracepoint names x86/perf, static_call: Optimize x86_pmu methods tracepoint: Optimize using static_call() static_call: Allow early init static_call: Add some validation static_call: Handle tail-calls static_call: Add static_call_cond() x86/alternatives: Teach text_poke_bp() to emulate RET static_call: Add simple self-test for static calls x86/static_call: Add inline static call implementation for x86-64 x86/static_call: Add out-of-line static call implementation static_call: Avoid kprobes on inline static_call()s static_call: Add inline static call infrastructure static_call: Add basic static call infrastructure compiler.h: Make __ADDRESSABLE() symbol truly unique jump_label,module: Fix module lifetime for __jump_label_mod_text_reserved() module: Properly propagate MODULE_STATE_COMING failure module: Fix up module_notifier return values ...
Diffstat (limited to 'tools/objtool')
-rw-r--r--tools/objtool/check.c138
-rw-r--r--tools/objtool/check.h1
-rw-r--r--tools/objtool/elf.c8
-rw-r--r--tools/objtool/elf.h3
-rw-r--r--tools/objtool/objtool.h1
-rw-r--r--tools/objtool/orc_gen.c4
-rwxr-xr-xtools/objtool/sync-check.sh1
7 files changed, 149 insertions, 7 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 2cc40db822a5..326ac390168b 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -16,6 +16,7 @@
#include <linux/hashtable.h>
#include <linux/kernel.h>
+#include <linux/static_call_types.h>
#define FAKE_JUMP_OFFSET -1
@@ -433,6 +434,103 @@ reachable:
return 0;
}
+static int create_static_call_sections(struct objtool_file *file)
+{
+ struct section *sec, *reloc_sec;
+ struct reloc *reloc;
+ struct static_call_site *site;
+ struct instruction *insn;
+ struct symbol *key_sym;
+ char *key_name, *tmp;
+ int idx;
+
+ sec = find_section_by_name(file->elf, ".static_call_sites");
+ if (sec) {
+ INIT_LIST_HEAD(&file->static_call_list);
+ WARN("file already has .static_call_sites section, skipping");
+ return 0;
+ }
+
+ if (list_empty(&file->static_call_list))
+ return 0;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->static_call_list, static_call_node)
+ idx++;
+
+ sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE,
+ sizeof(struct static_call_site), idx);
+ if (!sec)
+ return -1;
+
+ reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
+ if (!reloc_sec)
+ return -1;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->static_call_list, static_call_node) {
+
+ site = (struct static_call_site *)sec->data->d_buf + idx;
+ memset(site, 0, sizeof(struct static_call_site));
+
+ /* populate reloc for 'addr' */
+ reloc = malloc(sizeof(*reloc));
+ if (!reloc) {
+ perror("malloc");
+ return -1;
+ }
+ memset(reloc, 0, sizeof(*reloc));
+ reloc->sym = insn->sec->sym;
+ reloc->addend = insn->offset;
+ reloc->type = R_X86_64_PC32;
+ reloc->offset = idx * sizeof(struct static_call_site);
+ reloc->sec = reloc_sec;
+ elf_add_reloc(file->elf, reloc);
+
+ /* find key symbol */
+ key_name = strdup(insn->call_dest->name);
+ if (!key_name) {
+ perror("strdup");
+ return -1;
+ }
+ if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR,
+ STATIC_CALL_TRAMP_PREFIX_LEN)) {
+ WARN("static_call: trampoline name malformed: %s", key_name);
+ return -1;
+ }
+ tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
+ memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);
+
+ key_sym = find_symbol_by_name(file->elf, tmp);
+ if (!key_sym) {
+ WARN("static_call: can't find static_call_key symbol: %s", tmp);
+ return -1;
+ }
+ free(key_name);
+
+ /* populate reloc for 'key' */
+ reloc = malloc(sizeof(*reloc));
+ if (!reloc) {
+ perror("malloc");
+ return -1;
+ }
+ memset(reloc, 0, sizeof(*reloc));
+ reloc->sym = key_sym;
+ reloc->addend = is_sibling_call(insn) ? STATIC_CALL_SITE_TAIL : 0;
+ reloc->type = R_X86_64_PC32;
+ reloc->offset = idx * sizeof(struct static_call_site) + 4;
+ reloc->sec = reloc_sec;
+ elf_add_reloc(file->elf, reloc);
+
+ idx++;
+ }
+
+ if (elf_rebuild_reloc_section(file->elf, reloc_sec))
+ return -1;
+
+ return 0;
+}
+
/*
* Warnings shouldn't be reported for ignored functions.
*/
@@ -705,6 +803,10 @@ static int add_jump_destinations(struct objtool_file *file)
} else {
/* external sibling call */
insn->call_dest = reloc->sym;
+ if (insn->call_dest->static_call_tramp) {
+ list_add_tail(&insn->static_call_node,
+ &file->static_call_list);
+ }
continue;
}
@@ -756,6 +858,10 @@ static int add_jump_destinations(struct objtool_file *file)
/* internal sibling call */
insn->call_dest = insn->jump_dest->func;
+ if (insn->call_dest->static_call_tramp) {
+ list_add_tail(&insn->static_call_node,
+ &file->static_call_list);
+ }
}
}
}
@@ -1578,6 +1684,23 @@ static int read_intra_function_calls(struct objtool_file *file)
return 0;
}
+static int read_static_call_tramps(struct objtool_file *file)
+{
+ struct section *sec;
+ struct symbol *func;
+
+ for_each_sec(file, sec) {
+ list_for_each_entry(func, &sec->symbol_list, list) {
+ if (func->bind == STB_GLOBAL &&
+ !strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
+ strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
+ func->static_call_tramp = true;
+ }
+ }
+
+ return 0;
+}
+
static void mark_rodata(struct objtool_file *file)
{
struct section *sec;
@@ -1625,6 +1748,10 @@ static int decode_sections(struct objtool_file *file)
if (ret)
return ret;
+ ret = read_static_call_tramps(file);
+ if (ret)
+ return ret;
+
ret = add_jump_destinations(file);
if (ret)
return ret;
@@ -2488,6 +2615,11 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
if (dead_end_function(file, insn->call_dest))
return 0;
+ if (insn->type == INSN_CALL && insn->call_dest->static_call_tramp) {
+ list_add_tail(&insn->static_call_node,
+ &file->static_call_list);
+ }
+
break;
case INSN_JUMP_CONDITIONAL:
@@ -2847,6 +2979,7 @@ int check(const char *_objname, bool orc)
INIT_LIST_HEAD(&file.insn_list);
hash_init(file.insn_hash);
+ INIT_LIST_HEAD(&file.static_call_list);
file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");
file.ignore_unreachables = no_unreachable;
file.hints = false;
@@ -2894,6 +3027,11 @@ int check(const char *_objname, bool orc)
warnings += ret;
}
+ ret = create_static_call_sections(&file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+
if (orc) {
ret = create_orc(&file);
if (ret < 0)
diff --git a/tools/objtool/check.h b/tools/objtool/check.h
index 061aa96e15d3..36d38b9153ac 100644
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -22,6 +22,7 @@ struct insn_state {
struct instruction {
struct list_head list;
struct hlist_node hash;
+ struct list_head static_call_node;
struct section *sec;
unsigned long offset;
unsigned int len;
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 3ddbd66f1a37..4e1d7460574b 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -652,7 +652,7 @@ err:
}
struct section *elf_create_section(struct elf *elf, const char *name,
- size_t entsize, int nr)
+ unsigned int sh_flags, size_t entsize, int nr)
{
struct section *sec, *shstrtab;
size_t size = entsize * nr;
@@ -712,7 +712,7 @@ struct section *elf_create_section(struct elf *elf, const char *name,
sec->sh.sh_entsize = entsize;
sec->sh.sh_type = SHT_PROGBITS;
sec->sh.sh_addralign = 1;
- sec->sh.sh_flags = SHF_ALLOC;
+ sec->sh.sh_flags = SHF_ALLOC | sh_flags;
/* Add section name to .shstrtab (or .strtab for Clang) */
@@ -767,7 +767,7 @@ static struct section *elf_create_rel_reloc_section(struct elf *elf, struct sect
strcpy(relocname, ".rel");
strcat(relocname, base->name);
- sec = elf_create_section(elf, relocname, sizeof(GElf_Rel), 0);
+ sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rel), 0);
free(relocname);
if (!sec)
return NULL;
@@ -797,7 +797,7 @@ static struct section *elf_create_rela_reloc_section(struct elf *elf, struct sec
strcpy(relocname, ".rela");
strcat(relocname, base->name);
- sec = elf_create_section(elf, relocname, sizeof(GElf_Rela), 0);
+ sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rela), 0);
free(relocname);
if (!sec)
return NULL;
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index 6cc80a075166..807f8c670097 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -56,6 +56,7 @@ struct symbol {
unsigned int len;
struct symbol *pfunc, *cfunc, *alias;
bool uaccess_safe;
+ bool static_call_tramp;
};
struct reloc {
@@ -120,7 +121,7 @@ static inline u32 reloc_hash(struct reloc *reloc)
}
struct elf *elf_open_read(const char *name, int flags);
-struct section *elf_create_section(struct elf *elf, const char *name, size_t entsize, int nr);
+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 elf_add_reloc(struct elf *elf, struct reloc *reloc);
int elf_write_insn(struct elf *elf, struct section *sec,
diff --git a/tools/objtool/objtool.h b/tools/objtool/objtool.h
index 528028a66816..9a7cd0b88bd8 100644
--- a/tools/objtool/objtool.h
+++ b/tools/objtool/objtool.h
@@ -16,6 +16,7 @@ struct objtool_file {
struct elf *elf;
struct list_head insn_list;
DECLARE_HASHTABLE(insn_hash, 20);
+ struct list_head static_call_list;
bool ignore_unreachables, c_file, hints, rodata;
};
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index 968f55e6dd94..e6b2363c2e03 100644
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -177,7 +177,7 @@ int create_orc_sections(struct objtool_file *file)
/* create .orc_unwind_ip and .rela.orc_unwind_ip sections */
- sec = elf_create_section(file->elf, ".orc_unwind_ip", sizeof(int), idx);
+ sec = elf_create_section(file->elf, ".orc_unwind_ip", 0, sizeof(int), idx);
if (!sec)
return -1;
@@ -186,7 +186,7 @@ int create_orc_sections(struct objtool_file *file)
return -1;
/* create .orc_unwind section */
- u_sec = elf_create_section(file->elf, ".orc_unwind",
+ u_sec = elf_create_section(file->elf, ".orc_unwind", 0,
sizeof(struct orc_entry), idx);
/* populate sections */
diff --git a/tools/objtool/sync-check.sh b/tools/objtool/sync-check.sh
index 2a1261bfbb62..aa099b21dffa 100755
--- a/tools/objtool/sync-check.sh
+++ b/tools/objtool/sync-check.sh
@@ -7,6 +7,7 @@ arch/x86/include/asm/orc_types.h
arch/x86/include/asm/emulate_prefix.h
arch/x86/lib/x86-opcode-map.txt
arch/x86/tools/gen-insn-attr-x86.awk
+include/linux/static_call_types.h
'
check_2 () {