From: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Add a new interface stack_trace_save_shadow() for collecting stack traces by copying frames from the Shadow Call Stack. Collecting stack traces this way is significantly faster: boot time of a defconfig build with KASAN enabled gets descreased by ~30%. The few patches following this one add an implementation of stack_trace_save_shadow() for arm64. The implementation of the added interface is not meant to use stack_trace_consume_fn to avoid making a function call for each collected frame to further improve performance. Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> --- arch/Kconfig | 6 ++++++ include/linux/stacktrace.h | 15 +++++++++++++++ kernel/stacktrace.c | 21 +++++++++++++++++++++ 3 files changed, 42 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index e12a4268c01d..207c1679c53a 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -1041,6 +1041,12 @@ config HAVE_RELIABLE_STACKTRACE arch_stack_walk_reliable() function which only returns a stack trace if it can guarantee the trace is reliable. +config HAVE_SHADOW_STACKTRACE + bool + help + If this is set, the architecture provides the arch_stack_walk_shadow() + function, which collects the stack trace from the shadow call stack. + config HAVE_ARCH_HASH bool default n diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h index 97455880ac41..b74d1e42e157 100644 --- a/include/linux/stacktrace.h +++ b/include/linux/stacktrace.h @@ -60,6 +60,9 @@ int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, void *cookie, void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie, const struct pt_regs *regs); + +int arch_stack_walk_shadow(unsigned long *store, unsigned int size, + unsigned int skipnr); #endif /* CONFIG_ARCH_STACKWALK */ #ifdef CONFIG_STACKTRACE @@ -108,4 +111,16 @@ static inline int stack_trace_save_tsk_reliable(struct task_struct *tsk, } #endif +#if defined(CONFIG_STACKTRACE) && defined(CONFIG_HAVE_SHADOW_STACKTRACE) +int stack_trace_save_shadow(unsigned long *store, unsigned int size, + unsigned int skipnr); +#else +static inline int stack_trace_save_shadow(unsigned long *store, + unsigned int size, + unsigned int skipnr) +{ + return -ENOSYS; +} +#endif + #endif /* __LINUX_STACKTRACE_H */ diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c index 9ed5ce989415..fe305861fd55 100644 --- a/kernel/stacktrace.c +++ b/kernel/stacktrace.c @@ -237,6 +237,27 @@ unsigned int stack_trace_save_user(unsigned long *store, unsigned int size) } #endif +#ifdef CONFIG_HAVE_SHADOW_STACKTRACE +/** + * stack_trace_save_shadow - Save a stack trace based on shadow call stack + * @store: Pointer to the storage array + * @size: Size of the storage array + * @skipnr: Number of entries to skip at the start of the stack trace + * + * Return: Number of trace entries stored. + */ +int stack_trace_save_shadow(unsigned long *store, unsigned int size, + unsigned int skipnr) +{ + /* + * Do not use stack_trace_consume_fn to avoid making a function + * call for each collected frame to improve performance. + * Skip + 1 frame to skip stack_trace_save_shadow. + */ + return arch_stack_walk_shadow(store, size, skipnr + 1); +} +#endif + #else /* CONFIG_ARCH_STACKWALK */ /* -- 2.25.1