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Date: Tue, 15 Mar 2022 15:21:12 +0530
From: Maninder Singh <maninder1.s@...sung.com>
To: mcgrof@...nel.org, pmladek@...e.com, rostedt@...dmis.org,
senozhatsky@...omium.org, andriy.shevchenko@...ux.intel.com,
linux@...musvillemoes.dk, akpm@...ux-foundation.org,
wangkefeng.wang@...wei.com
Cc: v.narang@...sung.com, swboyd@...omium.org, ojeda@...nel.org,
linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org,
avimalin@...il.com, atomlin@...hat.com,
Maninder Singh <maninder1.s@...sung.com>
Subject: [PATCH v2] kallsyms: enhance %pS/s/b printing when KALLSYSMS is
disabled
print module information when KALLSYMS is disabled.
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 without KALLSYMS:
[7.870286] ps 0xffff800000f2008c [crash] // similar to original
[7.870716] pS 0x(____ptrval____)+0x8c [crash] // base address hashed and offset is without hash
[7.871025] pSb 0x(____ptrval____)+0x8c [crash 3423a8993a7033fb79e5add14bf9d8d6b56330ca]
[7.871321] pB 0x(____ptrval____)+0x8c [crash]
[7.871512] pBb 0x(____ptrval____)+0x8c [crash 3423a8993a7033fb79e5add14bf9d8d6b56330ca]
[7.872191] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
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@...e.com>
Co-developed-by: Vaneet Narang <v.narang@...sung.com>
Signed-off-by: Vaneet Narang <v.narang@...sung.com>
Signed-off-by: Maninder Singh <maninder1.s@...sung.com>
---
v1->v2: hash base address of module, change *fmt to fmt[0] and removed
copy paste.
include/linux/kallsyms.h | 2 +
include/linux/module.h | 22 +++++++++++
kernel/kallsyms.c | 26 ++++++-------
kernel/module.c | 4 +-
lib/vsprintf.c | 84 +++++++++++++++++++++++++++++++++-------
5 files changed, 109 insertions(+), 29 deletions(-)
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index e5ad6e31697d..c24fa627ab6e 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 1e135fd5c076..26a49e663351 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -678,6 +678,22 @@ static inline bool is_livepatch_module(struct module *mod)
bool is_module_sig_enforced(void);
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
+ len += sprintf(buffer + len, "]");
+
+ return len;
+}
#else /* !CONFIG_MODULES... */
static inline struct module *__module_address(unsigned long addr)
@@ -818,6 +834,12 @@ 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 57213e1d2349..cdbcaf86252a 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -479,19 +479,8 @@ 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;
}
@@ -586,6 +575,17 @@ 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);
+ else if (symbol)
+ return __sprint_symbol(buffer, address, 0, 1, build_id);
+ else
+ 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.c b/kernel/module.c
index 6cea788fd965..5756d31a024b 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1465,12 +1465,10 @@ resolve_symbol_wait(struct module *mod,
return ksym;
}
-#ifdef CONFIG_KALLSYMS
static inline bool sect_empty(const Elf_Shdr *sect)
{
return !(sect->sh_flags & SHF_ALLOC) || sect->sh_size == 0;
}
-#endif
/*
* /sys/module/foo/sections stuff
@@ -2799,7 +2797,7 @@ static void add_kallsyms(struct module *mod, const struct load_info *info)
}
#endif /* CONFIG_KALLSYMS */
-#if IS_ENABLED(CONFIG_KALLSYMS) && IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
static void init_build_id(struct module *mod, const struct load_info *info)
{
const Elf_Shdr *sechdr;
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 7adb8fd4d804..064b0cc45a37 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1000,33 +1000,91 @@ 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, char *end, unsigned long value,
+ const char *fmt, int modbuildid, int backtrace, int symbol)
+{
+ struct module *mod;
+ unsigned long offset = 0;
+ unsigned long base;
+ char *modname;
+ int len;
+ const unsigned char *buildid = NULL;
+
+ if (is_ksym_addr(value))
+ return 0;
+
+ if (backtrace || symbol)
+ offset = 1;
+
+ 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 (offset) {
+ base = (unsigned long)mod->core_layout.base;
+ offset = value - base;
+ }
+ }
+
+ preempt_enable();
+ if (!mod)
+ return 0;
+
+ /* address belongs to module */
+ if (offset)
+ len = sprintf(buf, "0x%p+0x%lx", (void *)base, offset);
+ else
+ len = sprintf(buf, "0x%lx", (void *)value);
+
+ len += fill_name_build_id(buf, modname, modbuildid, buildid, len);
+ return len;
+}
+#else
+static inline int sprint_module_info(char *buf, char *end, unsigned long value,
+ const char *fmt)
+{
+ 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, end, value, fmt, build_id, backtrace, symbol))
+ return string_nocheck(buf, end, sym, spec);
+
return special_hex_number(buf, end, value, sizeof(void *));
#endif
}
--
2.17.1
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