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Date: Mon, 28 Feb 2022 11:04:47 +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.or,
linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org,
avimalin@...il.com, atomlin@...hat.com,
Maninder Singh <maninder1.s@...sung.com>
Subject: [PATCH 1/1] kallsyms: enhance %pS/s/b printing when KALLSYSMS is
disabled
with commit '82b37e632513 ("kallsyms: print module name in %ps/S
case when KALLSYMS is disabled"), module name printing was enhanced.
As per suggestion from Petr Mladek <pmladek@...e.com>, covering
other flavours also to print build id also.
for %pB no change as it needs to know symbol name to adjust address
value which can't be done without KALLSYMS.
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]
original output without KALLSYMS:
[12.487424] ps 0xffff800000eb008c
[12.487598] pS 0xffff800000eb008c
[12.487723] pSb 0xffff800000eb008c
[12.487850] pB 0xffff800000eb008c
[12.487967] pBb 0xffff800000eb008c
With patched kernel without KALLSYMS:
[9.205207] ps 0xffff800000eb008c [crash]
[9.205564] pS 0xffff800000eb0000+0x8c [crash]
[9.205757] pSb 0xffff800000eb0000+0x8c [crash b367e79021b9f3b0172f9a36d4261c1f528ca1b3]
[9.206066] pB 0xffff800000eb0000+0x8c [crash]
[9.206257] pBb 0xffff800000eb0000+0x8c [crash b367e79021b9f3b0172f9a36d4261c1f528ca1b3]
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>
---
earlier discussion: https://lkml.org/lkml/2022/2/10/185
include/linux/kallsyms.h | 27 --------------
kernel/module.c | 4 +--
lib/vsprintf.c | 76 +++++++++++++++++++++++++++++++++++++++-
3 files changed, 76 insertions(+), 31 deletions(-)
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index ebfeb6099c28..5fb17dd4b6fa 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -163,33 +163,6 @@ static inline bool kallsyms_show_value(const struct cred *cred)
return false;
}
-#ifdef CONFIG_MODULES
-static inline int fill_minimal_module_info(char *sym, int size, unsigned long value)
-{
- struct module *mod;
- unsigned long offset;
- int ret = 0;
-
- preempt_disable();
- mod = __module_address(value);
- if (mod) {
- offset = value - (unsigned long)mod->core_layout.base;
- snprintf(sym, size - 1, "0x%lx+0x%lx [%s]",
- (unsigned long)mod->core_layout.base, offset, mod->name);
-
- sym[size - 1] = '\0';
- ret = 1;
- }
-
- preempt_enable();
- return ret;
-}
-#else
-static inline int fill_minimal_module_info(char *sym, int size, unsigned long value)
-{
- return 0;
-}
-#endif /*CONFIG_MODULES*/
#endif /*CONFIG_KALLSYMS*/
static inline void print_ip_sym(const char *loglvl, unsigned long ip)
diff --git a/kernel/module.c b/kernel/module.c
index 46a5c2ed1928..ccccb135c7fe 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 cb7345ff57f3..d4a24fd29494 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -980,6 +980,80 @@ 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)
+{
+ struct module *mod;
+ unsigned long offset = 1;
+ unsigned long base;
+ int ret = 0;
+ const char *modname;
+ int modbuildid = 0;
+ int len;
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+ const unsigned char *buildid = NULL;
+#endif
+
+ if (is_ksym_addr(value))
+ return 0;
+
+ if (*fmt == 'B' && fmt[1] == 'b')
+ modbuildid = 1;
+ else if (*fmt == 'S' && (fmt[1] == 'b' || (fmt[1] == 'R' && fmt[2] == 'b')))
+ modbuildid = 1;
+ else if (*fmt != 's') {
+ /*
+ * do nothing.
+ */
+ } else
+ offset = 0;
+
+ preempt_disable();
+ mod = __module_address(value);
+ if (mod) {
+ ret = 1;
+ 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 (!ret)
+ return 0;
+
+ /* address belongs to module */
+ if (offset)
+ len = sprintf(buf, "0x%lx+0x%lx", base, offset);
+ else
+ len = sprintf(buf, "0x%lx", value);
+
+ len += sprintf(buf + len, " [%s", modname);
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+ if (modbuildid && buildid) {
+ /* build ID should match length of sprintf */
+ static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
+ len += sprintf(buf + len, " %20phN", buildid);
+ }
+#endif
+ len += sprintf(buf + 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)
@@ -1005,7 +1079,7 @@ char *symbol_string(char *buf, char *end, void *ptr,
return string_nocheck(buf, end, sym, spec);
#else
- if (fill_minimal_module_info(sym, KSYM_SYMBOL_LEN, value))
+ if (sprint_module_info(sym, end, value, fmt))
return string_nocheck(buf, end, sym, spec);
return special_hex_number(buf, end, value, sizeof(void *));
--
2.17.1
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