[PATCH 1/1 module-testing] kallsyms: enhance %pS/s/b printing when KALLSYSMS is disabled
From: Maninder Singh
Date: Wed Mar 23 2022 - 13:50:04 EST
print module information when KALLSYMS is disabled.
init_build_id() function is moved to module/main.c as it can be
independent of kallsyms.
No change for %pB, as it needs to know symbol name to adjust address
value which can't be done without KALLSYMS.
(A) original output with KALLSYMS:
[8.842129] ps function_1 [crash]
[8.842735] pS function_1+0x4/0x2c [crash]
[8.842890] pSb function_1+0x4/0x2c [crash b367e79021b9f3b0172f9a36d4261c1f528ca1b3]
[8.843175] pB function_1+0x4/0x2c [crash]
[8.843362] pBb function_1+0x4/0x2c [crash b367e79021b9f3b0172f9a36d4261c1f528ca1b3]
(B) original output without KALLSYMS:
[12.487424] ps 0xffff800000eb008c
[12.487598] pS 0xffff800000eb008c
[12.487723] pSb 0xffff800000eb008c
[12.487850] pB 0xffff800000eb008c
[12.487967] pBb 0xffff800000eb008c
(C) With patched kernel
with KALLYSMS:
[41.974576] ps function_1 [crash]
[41.975173] pS function_1+0x4/0x2c [crash]
[41.975386] pSb function_1+0x4/0x2c [crash a8b20caaec9635b316cf4812f6b55598fe2b7cee]
[41.975879] pB function_1+0x4/0x2c [crash]
[41.976076] pBb function_1+0x4/0x2c [crash a8b20caaec9635b316cf4812f6b55598fe2b7cee]
without KALLSYMS:
[9.624152] ps 0xffff800001bd008c [crash] // similar to original, no changes
[9.624548] pS 0x(____ptrval____)+0x8c [crash] // base address hashed and offset is without hash
[9.624847] pSb 0x(____ptrval____)+0x8c [crash a8b20caaec9635b316cf4812f6b55598fe2b7cee]
[9.625388] pB 0x(____ptrval____)+0x8c [crash]
[9.625594] pBb 0x(____ptrval____)+0x8c [crash a8b20caaec9635b316cf4812f6b55598fe2b7cee]
with disable hashing:
[8.563916] ps 0xffff800000f2008c [crash]
[8.564574] pS 0xffff800000f20000+0x8c [crash]
[8.564749] pSb 0xffff800000f20000+0x8c [crash 3423a8993a7033fb79e5add14bf9d8d6b56330ca]
[8.565008] pB 0xffff800000f20000+0x8c [crash]
[8.565154] pBb 0xffff800000f20000+0x8c [crash 3423a8993a7033fb79e5add14bf9d8d6b56330ca]
Suggested-by: Petr Mladek <pmladek@xxxxxxxx>
Co-developed-by: Vaneet Narang <v.narang@xxxxxxxxxxx>
Signed-off-by: Vaneet Narang <v.narang@xxxxxxxxxxx>
Signed-off-by: Maninder Singh <maninder1.s@xxxxxxxxxxx>
Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
Tested-by: Petr Mladek <pmladek@xxxxxxxx>
---
module-next -> module-testing: Petr's review and test tag is picked from previous version,
current version has slight changes (module.c -> module/main.c). No functional change in patch,
only init_build_id() function is moved to module/main.c as it can be independent of
kallsyms.
include/linux/kallsyms.h | 2 +
include/linux/module.h | 20 ++++++++++
kernel/kallsyms.c | 27 +++++++------
kernel/module/internal.h | 11 +++---
kernel/module/kallsyms.c | 20 ----------
kernel/module/main.c | 20 ++++++++++
lib/vsprintf.c | 85 ++++++++++++++++++++++++++++++++++------
7 files changed, 133 insertions(+), 52 deletions(-)
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 4176c7eca7b5..1813ba9854f9 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -89,6 +89,8 @@ extern int sprint_symbol_build_id(char *buffer, unsigned long address);
extern int sprint_symbol_no_offset(char *buffer, unsigned long address);
extern int sprint_backtrace(char *buffer, unsigned long address);
extern int sprint_backtrace_build_id(char *buffer, unsigned long address);
+extern int sprint_kallsym_common(char *buffer, unsigned long address, int build_id,
+ int backtrace, int symbol);
int lookup_symbol_name(unsigned long addr, char *symname);
int lookup_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name);
diff --git a/include/linux/module.h b/include/linux/module.h
index 46d4d5f2516e..66f4491249c5 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -682,6 +682,20 @@ static inline bool is_livepatch_module(struct module *mod)
void set_module_sig_enforced(void);
+static inline int fill_name_build_id(char *buffer, char *modname,
+ int add_buildid, const unsigned char *buildid,
+ int len)
+{
+ len += sprintf(buffer + len, " [%s", modname);
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+ if (add_buildid && buildid) {
+ /* build ID should match length of sprintf */
+ static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
+ len += sprintf(buffer + len, " %20phN", buildid);
+ }
+#endif
+ return len + sprintf(buffer + len, "]");
+}
#else /* !CONFIG_MODULES... */
static inline struct module *__module_address(unsigned long addr)
@@ -818,6 +832,12 @@ void *dereference_module_function_descriptor(struct module *mod, void *ptr)
return ptr;
}
+static inline int fill_name_build_id(char *buffer, char *modname,
+ int add_buildid, const unsigned char *buildid,
+ int len)
+{
+ return 0;
+}
#endif /* CONFIG_MODULES */
#ifdef CONFIG_SYSFS
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 951c93216fc4..bd014504771d 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -461,19 +461,8 @@ static int __sprint_symbol(char *buffer, unsigned long address,
if (add_offset)
len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
- if (modname) {
- len += sprintf(buffer + len, " [%s", modname);
-#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
- if (add_buildid && buildid) {
- /* build ID should match length of sprintf */
-#if IS_ENABLED(CONFIG_MODULES)
- static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
-#endif
- len += sprintf(buffer + len, " %20phN", buildid);
- }
-#endif
- len += sprintf(buffer + len, "]");
- }
+ if (modname)
+ len += fill_name_build_id(buffer, modname, add_buildid, buildid, len);
return len;
}
@@ -568,6 +557,18 @@ int sprint_backtrace_build_id(char *buffer, unsigned long address)
return __sprint_symbol(buffer, address, -1, 1, 1);
}
+int sprint_kallsym_common(char *buffer, unsigned long address, int build_id,
+ int backtrace, int symbol)
+{
+ if (backtrace)
+ return __sprint_symbol(buffer, address, -1, 1, build_id);
+
+ if (symbol)
+ return __sprint_symbol(buffer, address, 0, 1, build_id);
+
+ return __sprint_symbol(buffer, address, 0, 0, 0);
+}
+
/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
struct kallsym_iter {
loff_t pos;
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 3e23bef5884d..cfff130f7c5f 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -206,21 +206,20 @@ static inline void kmemleak_load_module(const struct module *mod,
#endif /* CONFIG_DEBUG_KMEMLEAK */
#ifdef CONFIG_KALLSYMS
-void init_build_id(struct module *mod, const struct load_info *info);
void layout_symtab(struct module *mod, struct load_info *info);
void add_kallsyms(struct module *mod, const struct load_info *info);
unsigned long find_kallsyms_symbol_value(struct module *mod, const char *name);
-static inline bool sect_empty(const Elf_Shdr *sect)
-{
- return !(sect->sh_flags & SHF_ALLOC) || sect->sh_size == 0;
-}
#else /* !CONFIG_KALLSYMS */
-static inline void init_build_id(struct module *mod, const struct load_info *info) { }
static inline void layout_symtab(struct module *mod, struct load_info *info) { }
static inline void add_kallsyms(struct module *mod, const struct load_info *info) { }
#endif /* CONFIG_KALLSYMS */
+static inline bool sect_empty(const Elf_Shdr *sect)
+{
+ return !(sect->sh_flags & SHF_ALLOC) || sect->sh_size == 0;
+}
+
#ifdef CONFIG_SYSFS
int mod_sysfs_setup(struct module *mod, const struct load_info *info,
struct kernel_param *kparam, unsigned int num_params);
diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index 3e11523bc6f6..576a597615a7 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -209,26 +209,6 @@ void add_kallsyms(struct module *mod, const struct load_info *info)
mod->core_kallsyms.num_symtab = ndst;
}
-#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
-void init_build_id(struct module *mod, const struct load_info *info)
-{
- const Elf_Shdr *sechdr;
- unsigned int i;
-
- for (i = 0; i < info->hdr->e_shnum; i++) {
- sechdr = &info->sechdrs[i];
- if (!sect_empty(sechdr) && sechdr->sh_type == SHT_NOTE &&
- !build_id_parse_buf((void *)sechdr->sh_addr, mod->build_id,
- sechdr->sh_size))
- break;
- }
-}
-#else
-void init_build_id(struct module *mod, const struct load_info *info)
-{
-}
-#endif
-
/*
* This ignores the intensely annoying "mapping symbols" found
* in ARM ELF files: $a, $t and $d.
diff --git a/kernel/module/main.c b/kernel/module/main.c
index ce0ef17662c9..196521691ffe 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2657,6 +2657,26 @@ static int unknown_module_param_cb(char *param, char *val, const char *modname,
static void cfi_init(struct module *mod);
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+static void init_build_id(struct module *mod, const struct load_info *info)
+{
+ const Elf_Shdr *sechdr;
+ unsigned int i;
+
+ for (i = 0; i < info->hdr->e_shnum; i++) {
+ sechdr = &info->sechdrs[i];
+ if (!sect_empty(sechdr) && sechdr->sh_type == SHT_NOTE &&
+ !build_id_parse_buf((void *)sechdr->sh_addr, mod->build_id,
+ sechdr->sh_size))
+ break;
+ }
+}
+#else
+static inline void init_build_id(struct module *mod, const struct load_info *info)
+{
+}
+#endif
+
/*
* Allocate and load the module: note that size of section 0 is always
* zero, and we rely on this for optional sections.
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 36574a806a81..20060eb8c6d5 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -981,33 +981,92 @@ char *bdev_name(char *buf, char *end, struct block_device *bdev,
}
#endif
+#if !defined(CONFIG_KALLSYMS) && defined(CONFIG_MODULES)
+static int sprint_module_info(char *buf, unsigned long value,
+ int modbuildid, int backtrace, int symbol)
+{
+ struct module *mod;
+ unsigned long offset;
+ void *base;
+ char *modname;
+ int len;
+ const unsigned char *buildid = NULL;
+ bool add_offset;
+
+ if (is_ksym_addr(value))
+ return 0;
+
+ if (backtrace || symbol)
+ add_offset = true;
+ else
+ add_offset = false;
+
+ preempt_disable();
+ mod = __module_address(value);
+ if (mod) {
+ modname = mod->name;
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+ if (modbuildid)
+ buildid = mod->build_id;
+#endif
+ if (add_offset) {
+ base = mod->core_layout.base;
+ offset = value - (unsigned long)base;
+ }
+ }
+ preempt_enable();
+ if (!mod)
+ return 0;
+
+ /* address belongs to module */
+ if (add_offset)
+ len = sprintf(buf, "0x%p+0x%lx", base, offset);
+ else
+ len = sprintf(buf, "0x%lx", value);
+
+ return len + fill_name_build_id(buf, modname, modbuildid, buildid, len);
+}
+#else
+static inline int sprint_module_info(char *buf, unsigned long value,
+ int modbuildid, int backtrace, int symbol)
+{
+ return 0;
+}
+#endif
+
static noinline_for_stack
char *symbol_string(char *buf, char *end, void *ptr,
struct printf_spec spec, const char *fmt)
{
unsigned long value;
-#ifdef CONFIG_KALLSYMS
char sym[KSYM_SYMBOL_LEN];
-#endif
+ int backtrace = 0, symbol = 0, build_id = 0;
if (fmt[1] == 'R')
ptr = __builtin_extract_return_addr(ptr);
value = (unsigned long)ptr;
-#ifdef CONFIG_KALLSYMS
- if (*fmt == 'B' && fmt[1] == 'b')
- sprint_backtrace_build_id(sym, value);
- else if (*fmt == 'B')
- sprint_backtrace(sym, value);
- else if (*fmt == 'S' && (fmt[1] == 'b' || (fmt[1] == 'R' && fmt[2] == 'b')))
- sprint_symbol_build_id(sym, value);
- else if (*fmt != 's')
- sprint_symbol(sym, value);
- else
- sprint_symbol_no_offset(sym, value);
+ if (fmt[0] == 'B' && fmt[1] == 'b') {
+ backtrace = 1;
+ build_id = 1;
+ } else if (fmt[0] == 'B')
+ backtrace = 1;
+ else if (fmt[0] == 'S' && (fmt[1] == 'b' || (fmt[1] == 'R' && fmt[2] == 'b'))) {
+ symbol = 1;
+ build_id = 1;
+ } else if (fmt[0] != 's')
+ symbol = 1;
+ else {
+ /* Do Nothing, no offset */
+ }
+#ifdef CONFIG_KALLSYMS
+ sprint_kallsym_common(sym, value, build_id, backtrace, symbol);
return string_nocheck(buf, end, sym, spec);
#else
+ if (sprint_module_info(sym, value, build_id, backtrace, symbol))
+ return string_nocheck(buf, end, sym, spec);
+
return special_hex_number(buf, end, value, sizeof(void *));
#endif
}
--
2.17.1