diff mbox series

[1/1,module-testing] kallsyms: enhance %pS/s/b printing when KALLSYSMS is disabled

Message ID 20220323164742.2984281-1-maninder1.s@samsung.com (mailing list archive)
State New
Headers show
Series [1/1,module-testing] kallsyms: enhance %pS/s/b printing when KALLSYSMS is disabled | expand

Commit Message

Maninder Singh March 23, 2022, 4:47 p.m. UTC
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@suse.com>
Co-developed-by: Vaneet Narang <v.narang@samsung.com>
Signed-off-by: Vaneet Narang <v.narang@samsung.com>
Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
---
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(-)

Comments

Luis Chamberlain March 23, 2022, 10:04 p.m. UTC | #1
On Wed, Mar 23, 2022 at 10:17:42PM +0530, Maninder Singh wrote:
> ---
> 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.

Andrew,

I see this patch is merged on your tree, any chance we can yield until
the next release and I can then take it under modules-next ? It would
help given the slew of changes I now have queued up not for v5.18 but
for v5.19. I'm delaying the modules changes for v5.19 given the timing,
it is too soon to merge for v5.18 as I want tons of testing on this
all on linux-next after v5.18-rc1 is out.

  Luis
Andrew Morton March 23, 2022, 10:10 p.m. UTC | #2
On Wed, 23 Mar 2022 15:04:27 -0700 Luis Chamberlain <mcgrof@kernel.org> wrote:

> On Wed, Mar 23, 2022 at 10:17:42PM +0530, Maninder Singh wrote:
> > ---
> > 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.
> 
> Andrew,
> 
> I see this patch is merged on your tree, any chance we can yield until
> the next release and I can then take it under modules-next ? It would
> help given the slew of changes I now have queued up not for v5.18 but
> for v5.19. I'm delaying the modules changes for v5.19 given the timing,
> it is too soon to merge for v5.18 as I want tons of testing on this
> all on linux-next after v5.18-rc1 is out.
> 

I don't actually have this patch in -mm.  What I do have is the below,
which I shall now drop.  All yours to deal with as you see fit!



From: Maninder Singh <maninder1.s@samsung.com>
Subject: kallsyms: print module name in %ps/S case when KALLSYMS is disabled

original:
With KALLSYMS
                   %pS                               %ps
[16.4200]  hello_init+0x0/0x24 [crash]        hello_init [crash]

Without KALLSYMS:
[16.2200]      0xbe200040                         0xbe200040

With Patch (Without KALLSYMS:) load address + current offset [Module Name]

[13.5993]  0xbe200000+0x40 [crash]           0xbe200000+0x40 [crash]

It will help in better debugging and checking when KALLSYMS is disabled,
user will get information about module name and load address of module.

verified for arm64:
/ # insmod /crash.ko

[   19.263556] 0xffff800000ec0000+0x38 [crash]

..

[   19.276023] Call trace:
[   19.276277]  0xffff800000ec0000+0x28 [crash]
[   19.276567]  0xffff800000ec0000+0x58 [crash]
[   19.276727]  0xffff800000ec0000+0x74 [crash]
[   19.276866]  0xffff8000080127d0
[   19.276978]  0xffff80000812d95c
[   19.277085]  0xffff80000812f554

Link: https://lkml.kernel.org/r/20220201040044.1528568-1-maninder1.s@samsung.com
Signed-off-by: Vaneet Narang <v.narang@samsung.com>
Co-developed-by: Vaneet Narang <v.narang@samsung.com>
Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/kallsyms.h |   27 +++++++++++++++++++++++++++
 lib/vsprintf.c           |    5 +++--
 2 files changed, 30 insertions(+), 2 deletions(-)

--- a/include/linux/kallsyms.h~kallsyms-print-module-name-in-%ps-s-case-when-kallsyms-is-disabled
+++ a/include/linux/kallsyms.h
@@ -163,6 +163,33 @@ static inline bool kallsyms_show_value(c
 	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)
--- a/lib/vsprintf.c~kallsyms-print-module-name-in-%ps-s-case-when-kallsyms-is-disabled
+++ a/lib/vsprintf.c
@@ -984,9 +984,7 @@ char *symbol_string(char *buf, char *end
 		    struct printf_spec spec, const char *fmt)
 {
 	unsigned long value;
-#ifdef CONFIG_KALLSYMS
 	char sym[KSYM_SYMBOL_LEN];
-#endif
 
 	if (fmt[1] == 'R')
 		ptr = __builtin_extract_return_addr(ptr);
@@ -1006,6 +1004,9 @@ char *symbol_string(char *buf, char *end
 
 	return string_nocheck(buf, end, sym, spec);
 #else
+	if (fill_minimal_module_info(sym, KSYM_SYMBOL_LEN, value))
+		return string_nocheck(buf, end, sym, spec);
+
 	return special_hex_number(buf, end, value, sizeof(void *));
 #endif
 }
diff mbox series

Patch

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
 }