| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <YqxkhV1YcI6e+xXp@worktop.programming.kicks-ass.net>
Date: Fri, 17 Jun 2022 13:24:53 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org,
Josh Poimboeuf <jpoimboe@...hat.com>,
christophe.leroy@...roup.eu, naveen.n.rao@...ux.vnet.ibm.com,
mbenes@...e.cz
Subject: [RFC][PATCH] ftrace,objtool: PC32 based __mcount_loc
Hi,
I recently noticed that __mcount_loc is 64bit wide, containing absolute
addresses. Since __mcount_loc is a permanent section (not one we drop
after boot), this bloats the kernel memory usage for no real purpose.
The below patch adds __mcount_loc_32 and objtool support to generate it.
This saves, on an x86_64-defconfig + FTRACE, 23975*4 ~= 94K of permanent
storage.
XXX hobbled sorttable for now
XXX compile tested only
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
Makefile | 3 ++
arch/x86/Kconfig | 2 -
include/asm-generic/vmlinux.lds.h | 1
include/linux/ftrace.h | 6 -----
include/linux/ftrace_types.h | 21 +++++++++++++++++
include/linux/module.h | 3 +-
kernel/trace/Kconfig | 18 +++++++++++++++
kernel/trace/ftrace.c | 38 +++++++++++++++++++++-----------
scripts/Makefile.lib | 1
tools/objtool/builtin-check.c | 2 +
tools/objtool/check.c | 25 ++++++++++-----------
tools/objtool/include/objtool/builtin.h | 1
12 files changed, 90 insertions(+), 31 deletions(-)
--- a/Makefile
+++ b/Makefile
@@ -858,6 +858,9 @@ endif
ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT
endif
+ifdef CONFIG_FTRACE_MCOUNT32_USE_OBJTOOL
+ CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT -DCC_USING_MCOUNT_LOC_32
+endif
ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
ifdef CONFIG_HAVE_C_RECORDMCOUNT
BUILD_C_RECORDMCOUNT := y
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -190,7 +190,7 @@ config X86
select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
select HAVE_C_RECORDMCOUNT
select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
- select HAVE_BUILDTIME_MCOUNT_SORT
+ select HAVE_BUILDTIME_MCOUNT_SORT if !HAVE_OBJTOOL_MCOUNT
select HAVE_DEBUG_KMEMLEAK
select HAVE_DMA_CONTIGUOUS
select HAVE_DYNAMIC_FTRACE
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -172,6 +172,7 @@
#define MCOUNT_REC() . = ALIGN(8); \
__start_mcount_loc = .; \
KEEP(*(__mcount_loc)) \
+ KEEP(*(__mcount_loc_32)) \
KEEP(*(__patchable_function_entries)) \
__stop_mcount_loc = .; \
ftrace_stub_graph = ftrace_stub; \
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -19,6 +19,7 @@
#include <linux/types.h>
#include <linux/init.h>
#include <linux/fs.h>
+#include <linux/ftrace_types.h>
#include <asm/ftrace.h>
@@ -926,11 +927,6 @@ static inline unsigned long get_lock_par
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
extern void ftrace_init(void);
-#ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY
-#define FTRACE_CALLSITE_SECTION "__patchable_function_entries"
-#else
-#define FTRACE_CALLSITE_SECTION "__mcount_loc"
-#endif
#else
static inline void ftrace_init(void) { }
#endif
--- /dev/null
+++ b/include/linux/ftrace_types.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_FTRACE_TYPES_H
+#define _LINUX_FTRACE_TYPES_H
+
+#ifdef CONFIG_FTRACE_MCOUNT_RECORD
+
+#ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY
+#define FTRACE_CALLSITE_SECTION "__patchable_function_entries"
+typedef unsigned long mcount_t;
+#elif CC_USING_MCOUNT_LOC_32
+#define FTRACE_CALLSITE_SECTION "__mcount_loc_32"
+typedef u32 mcount_t;
+#else
+#define FTRACE_CALLSITE_SECTION "__mcount_loc"
+typedef unsigned long mcount_t;
+#endif
+
+#endif /* CONFIG_FTRACE_MCOUNT_RECORD */
+
+#endif /* _LINUX_FTRACE_TYPES_H */
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -28,6 +28,7 @@
#include <linux/srcu.h>
#include <linux/static_call_types.h>
#include <linux/cfi.h>
+#include <linux/ftrace_types.h>
#include <linux/percpu.h>
#include <asm/module.h>
@@ -493,7 +494,7 @@ struct module {
#endif
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
unsigned int num_ftrace_callsites;
- unsigned long *ftrace_callsites;
+ mcount_t *ftrace_callsites;
#endif
#ifdef CONFIG_KPROBES
void *kprobes_text_start;
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -717,16 +717,33 @@ config FTRACE_MCOUNT_USE_PATCHABLE_FUNCT
bool
depends on FTRACE_MCOUNT_RECORD
+#
+# mcount preference:
+# * objtool --mcount32
+# * gcc -mrecord-mcount
+# * objtool --mcount
+# * recordmcount
+#
+
+config FTRACE_MCOUNT32_USE_OBJTOOL
+ def_bool y
+ depends on HAVE_OBJTOOL_MCOUNT
+ depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
+ depends on FTRACE_MCOUNT_RECORD
+ select OBJTOOL
+
config FTRACE_MCOUNT_USE_CC
def_bool y
depends on $(cc-option,-mrecord-mcount)
depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
+ depends on !FTRACE_MCOUNT32_USE_OBJTOOL
depends on FTRACE_MCOUNT_RECORD
config FTRACE_MCOUNT_USE_OBJTOOL
def_bool y
depends on HAVE_OBJTOOL_MCOUNT
depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
+ depends on !FTRACE_MCOUNT32_USE_OBJTOOL
depends on !FTRACE_MCOUNT_USE_CC
depends on FTRACE_MCOUNT_RECORD
select OBJTOOL
@@ -735,6 +752,7 @@ config FTRACE_MCOUNT_USE_RECORDMCOUNT
def_bool y
depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
depends on !FTRACE_MCOUNT_USE_CC
+ depends on !FTRACE_MCOUNT32_USE_OBJTOOL
depends on !FTRACE_MCOUNT_USE_OBJTOOL
depends on FTRACE_MCOUNT_RECORD
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6544,18 +6544,26 @@ static __init int ftrace_init_dyn_tracef
static int ftrace_cmp_ips(const void *a, const void *b)
{
- const unsigned long *ipa = a;
- const unsigned long *ipb = b;
+ const mcount_t *_a = a;
+ const mcount_t *_b = b;
- if (*ipa > *ipb)
+#ifdef CC_USING_MCOUNT_LOC_32
+ const unsigned long ipa = (unsigned long)_a + *_a;
+ const unsigned long ipb = (unsigned long)_b + *_b;
+#else
+ const unsigned long ipa = *_a;
+ const unsigned long ipb = *_b;
+#endif
+
+ if (ipa > ipb)
return 1;
- if (*ipa < *ipb)
+ if (ipa < ipb)
return -1;
return 0;
}
#ifdef CONFIG_FTRACE_SORT_STARTUP_TEST
-static void test_is_sorted(unsigned long *start, unsigned long count)
+static void test_is_sorted(mcount_t *start, unsigned long count)
{
int i;
@@ -6570,23 +6578,23 @@ static void test_is_sorted(unsigned long
pr_info("ftrace section at %px sorted properly\n", start);
}
#else
-static void test_is_sorted(unsigned long *start, unsigned long count)
+static void test_is_sorted(mcount_t *start, unsigned long count)
{
}
#endif
static int ftrace_process_locs(struct module *mod,
- unsigned long *start,
- unsigned long *end)
+ mcount_t *start,
+ mcount_t *end)
{
struct ftrace_page *start_pg;
struct ftrace_page *pg;
struct dyn_ftrace *rec;
unsigned long count;
- unsigned long *p;
unsigned long addr;
unsigned long flags = 0; /* Shut up gcc */
int ret = -ENOMEM;
+ mcount_t *p;
count = end - start;
@@ -6637,7 +6645,13 @@ static int ftrace_process_locs(struct mo
pg = start_pg;
while (p < end) {
unsigned long end_offset;
- addr = ftrace_call_adjust(*p++);
+#ifdef CC_USING_MCOUNT_LOC_32
+ addr = (unsigned long)p + *p;
+ p++;
+#else
+ addr = *p++;
+#endif
+ addr = ftrace_call_adjust(addr);
/*
* Some architecture linkers will pad between
* the different mcount_loc sections of different
@@ -7280,8 +7294,8 @@ int __init __weak ftrace_dyn_arch_init(v
void __init ftrace_init(void)
{
- extern unsigned long __start_mcount_loc[];
- extern unsigned long __stop_mcount_loc[];
+ extern mcount_t __start_mcount_loc[];
+ extern mcount_t __stop_mcount_loc[];
unsigned long count, flags;
int ret;
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -234,6 +234,7 @@ objtool_args = \
$(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr) \
$(if $(CONFIG_X86_KERNEL_IBT), --ibt) \
$(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \
+ $(if $(CONFIG_FTRACE_MCOUNT32_USE_OBJTOOL), --mcount32) \
$(if $(CONFIG_UNWINDER_ORC), --orc) \
$(if $(CONFIG_RETPOLINE), --retpoline) \
$(if $(CONFIG_SLS), --sls) \
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -65,6 +65,7 @@ const struct option check_options[] = {
OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr", "patch toolchain bugs/limitations", parse_hacks),
OPT_BOOLEAN('i', "ibt", &opts.ibt, "validate and annotate IBT"),
OPT_BOOLEAN('m', "mcount", &opts.mcount, "annotate mcount/fentry calls for ftrace"),
+ OPT_BOOLEAN(0, "mcount32", &opts.mcount32, "annotate mcount/fentry calls for ftrace"),
OPT_BOOLEAN('n', "noinstr", &opts.noinstr, "validate noinstr rules"),
OPT_BOOLEAN('o', "orc", &opts.orc, "generate ORC metadata"),
OPT_BOOLEAN('r', "retpoline", &opts.retpoline, "validate and annotate retpoline usage"),
@@ -120,6 +121,7 @@ static bool opts_valid(void)
opts.hack_noinstr ||
opts.ibt ||
opts.mcount ||
+ opts.mcount32 ||
opts.noinstr ||
opts.orc ||
opts.retpoline ||
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -803,15 +803,16 @@ static int create_ibt_endbr_seal_section
static int create_mcount_loc_sections(struct objtool_file *file)
{
- struct section *sec;
- unsigned long *loc;
+ const char *secname = opts.mcount32 ? "__mcount_loc_32" : "__mcount_loc";
+ unsigned int entsize = opts.mcount32 ? sizeof(u32) : sizeof(u64);
struct instruction *insn;
+ struct section *sec;
int idx;
- sec = find_section_by_name(file->elf, "__mcount_loc");
+ sec = find_section_by_name(file->elf, secname);
if (sec) {
INIT_LIST_HEAD(&file->mcount_loc_list);
- WARN("file already has __mcount_loc section, skipping");
+ WARN("file already has %s section, skipping", secname);
return 0;
}
@@ -822,19 +823,18 @@ static int create_mcount_loc_sections(st
list_for_each_entry(insn, &file->mcount_loc_list, call_node)
idx++;
- sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx);
+ sec = elf_create_section(file->elf, secname, 0, entsize, idx);
if (!sec)
return -1;
idx = 0;
list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
-
- loc = (unsigned long *)sec->data->d_buf + idx;
- memset(loc, 0, sizeof(unsigned long));
+ void *loc = sec->data->d_buf + idx * entsize;
+ memset(loc, 0, entsize);
if (elf_add_reloc_to_insn(file->elf, sec,
- idx * sizeof(unsigned long),
- R_X86_64_64,
+ idx * entsize,
+ opts.mcount32 ? R_X86_64_PC32 : R_X86_64_64,
insn->sec, insn->offset))
return -1;
@@ -1174,7 +1174,7 @@ static void annotate_call_site(struct ob
return;
}
- if (opts.mcount && sym->fentry) {
+ if ((opts.mcount || opts.mcount32) && sym->fentry) {
if (sibling)
WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec, insn->offset);
@@ -3827,6 +3827,7 @@ static int validate_ibt(struct objtool_f
!strcmp(sec->name, "__ex_table") ||
!strcmp(sec->name, "__jump_table") ||
!strcmp(sec->name, "__mcount_loc") ||
+ !strcmp(sec->name, "__mcount_loc_32") ||
!strcmp(sec->name, "__tracepoints"))
continue;
@@ -3974,7 +3975,7 @@ int check(struct objtool_file *file)
warnings += ret;
}
- if (opts.mcount) {
+ if (opts.mcount || opts.mcount32) {
ret = create_mcount_loc_sections(file);
if (ret < 0)
goto out;
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -16,6 +16,7 @@ struct opts {
bool hack_noinstr;
bool ibt;
bool mcount;
+ bool mcount32;
bool noinstr;
bool orc;
bool retpoline;
Powered by blists - more mailing lists