From 3f045de7f557850ca6b3632c6d45c2cdaf948694 Mon Sep 17 00:00:00 2001 From: Nam Cao Date: Wed, 9 Jul 2025 21:21:14 +0200 Subject: panic: Add vpanic() vpanic() is useful for implementing runtime verification reactors. Add it. Signed-off-by: Nam Cao Reviewed-by: Petr Mladek Signed-off-by: Steven Rostedt (Google) --- kernel/panic.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index b0b9a8bf4560..6a1823c383d0 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -309,13 +309,13 @@ static void panic_other_cpus_shutdown(bool crash_kexec) /** * panic - halt the system * @fmt: The text string to print + * @args: Arguments for the format string * * Display a message, then perform cleanups. This function never returns. */ -void panic(const char *fmt, ...) +void vpanic(const char *fmt, va_list args) { static char buf[1024]; - va_list args; long i, i_next = 0, len; int state = 0; int old_cpu, this_cpu; @@ -366,9 +366,7 @@ void panic(const char *fmt, ...) console_verbose(); bust_spinlocks(1); - va_start(args, fmt); len = vscnprintf(buf, sizeof(buf), fmt, args); - va_end(args); if (len && buf[len - 1] == '\n') buf[len - 1] = '\0'; @@ -505,7 +503,17 @@ void panic(const char *fmt, ...) mdelay(PANIC_TIMER_STEP); } } +EXPORT_SYMBOL(vpanic); +/* Identical to vpanic(), except it takes variadic arguments instead of va_list */ +void panic(const char *fmt, ...) +{ + va_list args; + + va_start(args, fmt); + vpanic(fmt, args); + va_end(args); +} EXPORT_SYMBOL(panic); #define TAINT_FLAG(taint, _c_true, _c_false, _module) \ -- cgit v1.2.3 From 9a425da913cf4ea23040334301fce87be2dab384 Mon Sep 17 00:00:00 2001 From: Nam Cao Date: Fri, 11 Jul 2025 13:20:43 +0200 Subject: panic: Fix up description of vpanic() The description above vpanic() has the wrong function name. Fix it up. Cc: John Ogness Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Gabriele Monaco Cc: Josh Poimboeuf Cc: Petr Mladek Link: https://lore.kernel.org/23a7e8add6546b155371b7e0fbb37bb1def13d6e.1752232374.git.namcao@linutronix.de Reported-by: Stephen Rothwell Closes: https://lore.kernel.org/lkml/20250711183802.2d8c124d@canb.auug.org.au/ Acked-by: Peter Zijlstra (Intel) Signed-off-by: Nam Cao Signed-off-by: Steven Rostedt (Google) --- kernel/panic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index 6a1823c383d0..2a499facde13 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -307,7 +307,7 @@ static void panic_other_cpus_shutdown(bool crash_kexec) } /** - * panic - halt the system + * vpanic - halt the system * @fmt: The text string to print * @args: Arguments for the format string * -- cgit v1.2.3 From 261743b0135d1d578cab407ba0cf226df30b43d8 Mon Sep 17 00:00:00 2001 From: Feng Tang Date: Thu, 3 Jul 2025 10:10:00 +0800 Subject: panic: clean up code for console replay Patch series "generalize panic_print's dump function to be used by other kernel parts", v3. When working on kernel stability issues, panic, task-hung and software/hardware lockup are frequently met. And to debug them, user may need lots of system information at that time, like task call stacks, lock info, memory info etc. panic case already has panic_print_sys_info() for this purpose, and has a 'panic_print' bitmask to control what kinds of information is needed, which is also helpful to debug other task-hung and lockup cases. So this patchset extracts the function out to a new file 'lib/sys_info.c', and makes it available for other cases which also need to dump system info for debugging. Also as suggested by Petr Mladek, add 'panic_sys_info=' interface to take human readable string like "tasks,mem,locks,timers,ftrace,....", and eventually obsolete the current 'panic_print' bitmap interface. In RFC and V1 version, hung_task and SW/HW watchdog modules are enabled with the new sys_info dump interface. In v2, they are kept out for better review of current change, and will be posted later. Locally these have been used in our bug chasing for stability issues and was proven helpful. Many thanks to Petr Mladek for great suggestions on both the code and architectures! This patch (of 5): Currently the panic_print_sys_info() was called twice with different parameters to handle console replay case, which is kind of confusing. Add panic_console_replay() explicitly and rename 'PANIC_PRINT_ALL_PRINTK_MSG' to 'PANIC_CONSOLE_REPLAY', to make the code straightforward. The related kernel document is also updated. Link: https://lkml.kernel.org/r/20250703021004.42328-1-feng.tang@linux.alibaba.com Link: https://lkml.kernel.org/r/20250703021004.42328-2-feng.tang@linux.alibaba.com Signed-off-by: Feng Tang Suggested-by: Petr Mladek Reviewed-by: Petr Mladek Cc: John Ogness Cc: Jonathan Corbet Cc: Lance Yang Cc: "Paul E . McKenney" Cc: Steven Rostedt Cc: Nathan Chancellor Signed-off-by: Andrew Morton --- kernel/panic.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index b0b9a8bf4560..9b6c5dc28a65 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -74,7 +74,7 @@ EXPORT_SYMBOL_GPL(panic_timeout); #define PANIC_PRINT_TIMER_INFO 0x00000004 #define PANIC_PRINT_LOCK_INFO 0x00000008 #define PANIC_PRINT_FTRACE_INFO 0x00000010 -#define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020 +#define PANIC_CONSOLE_REPLAY 0x00000020 #define PANIC_PRINT_ALL_CPU_BT 0x00000040 #define PANIC_PRINT_BLOCKED_TASKS 0x00000080 unsigned long panic_print; @@ -238,14 +238,14 @@ void nmi_panic(struct pt_regs *regs, const char *msg) } EXPORT_SYMBOL(nmi_panic); -static void panic_print_sys_info(bool console_flush) +static void panic_console_replay(void) { - if (console_flush) { - if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG) - console_flush_on_panic(CONSOLE_REPLAY_ALL); - return; - } + if (panic_print & PANIC_CONSOLE_REPLAY) + console_flush_on_panic(CONSOLE_REPLAY_ALL); +} +static void panic_print_sys_info(void) +{ if (panic_print & PANIC_PRINT_TASK_INFO) show_state(); @@ -410,7 +410,7 @@ void panic(const char *fmt, ...) */ atomic_notifier_call_chain(&panic_notifier_list, 0, buf); - panic_print_sys_info(false); + panic_print_sys_info(); kmsg_dump_desc(KMSG_DUMP_PANIC, buf); @@ -439,7 +439,7 @@ void panic(const char *fmt, ...) debug_locks_off(); console_flush_on_panic(CONSOLE_FLUSH_PENDING); - panic_print_sys_info(true); + panic_console_replay(); if (!panic_blink) panic_blink = no_blink; -- cgit v1.2.3 From b76e89e50fc3693b7b8a443ed906320d8ccb93fd Mon Sep 17 00:00:00 2001 From: Feng Tang Date: Thu, 3 Jul 2025 10:10:01 +0800 Subject: panic: generalize panic_print's function to show sys info 'panic_print' was introduced to help debugging kernel panic by dumping different kinds of system information like tasks' call stack, memory, ftrace buffer, etc. Actually this function could also be used to help debugging other cases like task-hung, soft/hard lockup, etc. where user may need the snapshot of system info at that time. Extract system info dump function related code from panic.c to separate file sys_info.[ch], for wider usage by other kernel parts for debugging. Also modify the macro names about singulars/plurals. Link: https://lkml.kernel.org/r/20250703021004.42328-3-feng.tang@linux.alibaba.com Signed-off-by: Feng Tang Suggested-by: Petr Mladek Cc: John Ogness Cc: Jonathan Corbet Cc: Lance Yang Cc: "Paul E . McKenney" Cc: Steven Rostedt Cc: Nathan Chancellor Signed-off-by: Andrew Morton --- kernel/panic.c | 36 ++++-------------------------------- 1 file changed, 4 insertions(+), 32 deletions(-) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index 9b6c5dc28a65..cbb0681177b3 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -36,6 +36,7 @@ #include #include #include +#include #include #include @@ -69,14 +70,6 @@ bool panic_triggering_all_cpu_backtrace; int panic_timeout = CONFIG_PANIC_TIMEOUT; EXPORT_SYMBOL_GPL(panic_timeout); -#define PANIC_PRINT_TASK_INFO 0x00000001 -#define PANIC_PRINT_MEM_INFO 0x00000002 -#define PANIC_PRINT_TIMER_INFO 0x00000004 -#define PANIC_PRINT_LOCK_INFO 0x00000008 -#define PANIC_PRINT_FTRACE_INFO 0x00000010 -#define PANIC_CONSOLE_REPLAY 0x00000020 -#define PANIC_PRINT_ALL_CPU_BT 0x00000040 -#define PANIC_PRINT_BLOCKED_TASKS 0x00000080 unsigned long panic_print; ATOMIC_NOTIFIER_HEAD(panic_notifier_list); @@ -240,31 +233,10 @@ EXPORT_SYMBOL(nmi_panic); static void panic_console_replay(void) { - if (panic_print & PANIC_CONSOLE_REPLAY) + if (panic_print & SYS_INFO_PANIC_CONSOLE_REPLAY) console_flush_on_panic(CONSOLE_REPLAY_ALL); } -static void panic_print_sys_info(void) -{ - if (panic_print & PANIC_PRINT_TASK_INFO) - show_state(); - - if (panic_print & PANIC_PRINT_MEM_INFO) - show_mem(); - - if (panic_print & PANIC_PRINT_TIMER_INFO) - sysrq_timer_list_show(); - - if (panic_print & PANIC_PRINT_LOCK_INFO) - debug_show_all_locks(); - - if (panic_print & PANIC_PRINT_FTRACE_INFO) - ftrace_dump(DUMP_ALL); - - if (panic_print & PANIC_PRINT_BLOCKED_TASKS) - show_state_filter(TASK_UNINTERRUPTIBLE); -} - void check_panic_on_warn(const char *origin) { unsigned int limit; @@ -285,7 +257,7 @@ void check_panic_on_warn(const char *origin) */ static void panic_other_cpus_shutdown(bool crash_kexec) { - if (panic_print & PANIC_PRINT_ALL_CPU_BT) { + if (panic_print & SYS_INFO_ALL_CPU_BT) { /* Temporary allow non-panic CPUs to write their backtraces. */ panic_triggering_all_cpu_backtrace = true; trigger_all_cpu_backtrace(); @@ -410,7 +382,7 @@ void panic(const char *fmt, ...) */ atomic_notifier_call_chain(&panic_notifier_list, 0, buf); - panic_print_sys_info(); + sys_info(panic_print); kmsg_dump_desc(KMSG_DUMP_PANIC, buf); -- cgit v1.2.3 From d747755917bf8ae08f490c3fe7d8e321afab8127 Mon Sep 17 00:00:00 2001 From: Feng Tang Date: Thu, 3 Jul 2025 10:10:02 +0800 Subject: panic: add 'panic_sys_info' sysctl to take human readable string parameter Bitmap definition for 'panic_print' is hard to remember and decode. Add 'panic_sys_info='sysctl to take human readable string like "tasks,mem,timers,locks,ftrace,..." and translate it into bitmap. The detailed mapping is: SYS_INFO_TASKS "tasks" SYS_INFO_MEM "mem" SYS_INFO_TIMERS "timers" SYS_INFO_LOCKS "locks" SYS_INFO_FTRACE "ftrace" SYS_INFO_ALL_CPU_BT "all_bt" SYS_INFO_BLOCKED_TASKS "blocked_tasks" [nathan@kernel.org: add __maybe_unused to sys_info_avail] Link: https://lkml.kernel.org/r/20250708-fix-clang-sys_info_avail-warning-v1-1-60d239eacd64@kernel.org Link: https://lkml.kernel.org/r/20250703021004.42328-4-feng.tang@linux.alibaba.com Signed-off-by: Feng Tang Suggested-by: Petr Mladek Cc: John Ogness Cc: Jonathan Corbet Cc: Lance Yang Cc: "Paul E . McKenney" Cc: Steven Rostedt Cc: Nathan Chancellor Cc: Andy Shevchenko Signed-off-by: Andrew Morton --- kernel/panic.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index cbb0681177b3..d7aa427dc23c 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -126,6 +126,13 @@ static const struct ctl_table kern_panic_table[] = { .mode = 0644, .proc_handler = proc_douintvec, }, + { + .procname = "panic_sys_info", + .data = &panic_print, + .maxlen = sizeof(panic_print), + .mode = 0644, + .proc_handler = sysctl_sys_info_handler, + }, }; static __init int kernel_panic_sysctls_init(void) -- cgit v1.2.3 From 9743d12d0c63968320ece31e2e48723f3235be6d Mon Sep 17 00:00:00 2001 From: Feng Tang Date: Thu, 3 Jul 2025 10:10:03 +0800 Subject: panic: add 'panic_sys_info=' setup option for kernel cmdline 'panic_sys_info=' sysctl interface is already added for runtime setting. Add counterpart kernel cmdline option for boottime setting. Link: https://lkml.kernel.org/r/20250703021004.42328-5-feng.tang@linux.alibaba.com Signed-off-by: Feng Tang Suggested-by: Petr Mladek Cc: John Ogness Cc: Jonathan Corbet Cc: Lance Yang Cc: "Paul E . McKenney" Cc: Steven Rostedt Cc: Nathan Chancellor Signed-off-by: Andrew Morton --- kernel/panic.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index d7aa427dc23c..d9d4fcd5e318 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -143,6 +143,15 @@ static __init int kernel_panic_sysctls_init(void) late_initcall(kernel_panic_sysctls_init); #endif +/* The format is "panic_sys_info=tasks,mem,locks,ftrace,..." */ +static int __init setup_panic_sys_info(char *buf) +{ + /* There is no risk of race in kernel boot phase */ + panic_print = sys_info_parse_param(buf); + return 1; +} +__setup("panic_sys_info=", setup_panic_sys_info); + static atomic_t warn_count = ATOMIC_INIT(0); #ifdef CONFIG_SYSFS -- cgit v1.2.3 From ee13240cd78b68430eb50af4721b3f18dd08af29 Mon Sep 17 00:00:00 2001 From: Feng Tang Date: Thu, 3 Jul 2025 10:10:04 +0800 Subject: panic: add note that panic_print sysctl interface is deprecated Add a dedicated core parameter 'panic_console_replay' for controlling console replay, and add note that 'panic_print' sysctl interface will be obsoleted by 'panic_sys_info' and 'panic_console_replay'. When it happens, the SYS_INFO_PANIC_CONSOLE_REPLAY can be removed as well. Link: https://lkml.kernel.org/r/20250703021004.42328-6-feng.tang@linux.alibaba.com Signed-off-by: Feng Tang Suggested-by: Petr Mladek Cc: John Ogness Cc: Jonathan Corbet Cc: Lance Yang Cc: "Paul E . McKenney" Cc: Steven Rostedt Cc: Nathan Chancellor Signed-off-by: Andrew Morton --- kernel/panic.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index d9d4fcd5e318..bb16f254cd02 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -64,6 +64,7 @@ int panic_on_warn __read_mostly; unsigned long panic_on_taint; bool panic_on_taint_nousertaint = false; static unsigned int warn_limit __read_mostly; +static bool panic_console_replay; bool panic_triggering_all_cpu_backtrace; @@ -77,6 +78,13 @@ ATOMIC_NOTIFIER_HEAD(panic_notifier_list); EXPORT_SYMBOL(panic_notifier_list); #ifdef CONFIG_SYSCTL +static int sysctl_panic_print_handler(const struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) +{ + pr_info_once("Kernel: 'panic_print' sysctl interface will be obsoleted by both 'panic_sys_info' and 'panic_console_replay'\n"); + return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); +} + static const struct ctl_table kern_panic_table[] = { #ifdef CONFIG_SMP { @@ -108,7 +116,7 @@ static const struct ctl_table kern_panic_table[] = { .data = &panic_print, .maxlen = sizeof(unsigned long), .mode = 0644, - .proc_handler = proc_doulongvec_minmax, + .proc_handler = sysctl_panic_print_handler, }, { .procname = "panic_on_warn", @@ -247,12 +255,6 @@ void nmi_panic(struct pt_regs *regs, const char *msg) } EXPORT_SYMBOL(nmi_panic); -static void panic_console_replay(void) -{ - if (panic_print & SYS_INFO_PANIC_CONSOLE_REPLAY) - console_flush_on_panic(CONSOLE_REPLAY_ALL); -} - void check_panic_on_warn(const char *origin) { unsigned int limit; @@ -427,7 +429,9 @@ void panic(const char *fmt, ...) debug_locks_off(); console_flush_on_panic(CONSOLE_FLUSH_PENDING); - panic_console_replay(); + if ((panic_print & SYS_INFO_PANIC_CONSOLE_REPLAY) || + panic_console_replay) + console_flush_on_panic(CONSOLE_REPLAY_ALL); if (!panic_blink) panic_blink = no_blink; @@ -869,6 +873,7 @@ core_param(panic_print, panic_print, ulong, 0644); core_param(pause_on_oops, pause_on_oops, int, 0644); core_param(panic_on_warn, panic_on_warn, int, 0644); core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644); +core_param(panic_console_replay, panic_console_replay, bool, 0644); static int __init oops_setup(char *s) { -- cgit v1.2.3 From 942b296a6c35da6593eeeb126dce71d4e506f314 Mon Sep 17 00:00:00 2001 From: Joel Granados Date: Mon, 5 May 2025 21:20:07 +0200 Subject: sysctl: Move tainted ctl_table into kernel/panic.c Move the ctl_table with the "tainted" proc_name into kernel/panic.c. With it moves the proc_tainted helper function. This is part of a greater effort to move ctl tables into their respective subsystems which will reduce the merge conflicts in kernel/sysctl.c. Reviewed-by: Luis Chamberlain Reviewed-by: Kees Cook Signed-off-by: Joel Granados --- kernel/panic.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index b0b9a8bf4560..39e5b1ddf1a8 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -84,6 +84,50 @@ ATOMIC_NOTIFIER_HEAD(panic_notifier_list); EXPORT_SYMBOL(panic_notifier_list); #ifdef CONFIG_SYSCTL + +/* + * Taint values can only be increased + * This means we can safely use a temporary. + */ +static int proc_taint(const struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) +{ + struct ctl_table t; + unsigned long tmptaint = get_taint(); + int err; + + if (write && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + t = *table; + t.data = &tmptaint; + err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); + if (err < 0) + return err; + + if (write) { + int i; + + /* + * If we are relying on panic_on_taint not producing + * false positives due to userspace input, bail out + * before setting the requested taint flags. + */ + if (panic_on_taint_nousertaint && (tmptaint & panic_on_taint)) + return -EINVAL; + + /* + * Poor man's atomic or. Not worth adding a primitive + * to everyone's atomic.h for this + */ + for (i = 0; i < TAINT_FLAGS_COUNT; i++) + if ((1UL << i) & tmptaint) + add_taint(i, LOCKDEP_STILL_OK); + } + + return err; +} + static const struct ctl_table kern_panic_table[] = { #ifdef CONFIG_SMP { @@ -96,6 +140,12 @@ static const struct ctl_table kern_panic_table[] = { .extra2 = SYSCTL_ONE, }, #endif + { + .procname = "tainted", + .maxlen = sizeof(long), + .mode = 0644, + .proc_handler = proc_taint, + }, { .procname = "panic", .data = &panic_timeout, -- cgit v1.2.3 From 5a477e934152d0b32201000444d7a5e8358c9480 Mon Sep 17 00:00:00 2001 From: Joel Granados Date: Thu, 8 May 2025 21:35:27 +0200 Subject: sysctl: Move sysctl_panic_on_stackoverflow to kernel/panic.c This is part of a greater effort to move ctl tables into their respective subsystems which will reduce the merge conflicts in kernel/sysctl.c. Reviewed-by: Kees Cook Signed-off-by: Joel Granados --- kernel/panic.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index 39e5b1ddf1a8..64e58835086d 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -183,6 +183,16 @@ static const struct ctl_table kern_panic_table[] = { .mode = 0644, .proc_handler = proc_douintvec, }, +#if (defined(CONFIG_X86_32) || defined(CONFIG_PARISC)) && \ + defined(CONFIG_DEBUG_STACKOVERFLOW) + { + .procname = "panic_on_stackoverflow", + .data = &sysctl_panic_on_stackoverflow, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, +#endif }; static __init int kernel_panic_sysctls_init(void) -- cgit v1.2.3