2017-04-25 15:44 GMT+02:00 Enric Balletbo i Serra <[email protected]>: > Dump a block of kernel memory from around the registers in the kernel oops > dump. This is behind a config option (DEBUG_AROUND_REGS), since it adds > a bunch of noise to the kernel logs (which someone can find valuable but > not everyone else will). > > This is extremely useful in diagnosing remote crashes, and is based heavily > on original work by Michael Davidson <[email protected]> and San Mehat > <[email protected]>. > > Signed-off-by: Enric Balletbo i Serra <[email protected]> > --- > This is a second version of a patch that was initially sent by John Stultz > in 2010[1], current version is a rework trying to address the feedback > received in the first version. We're still carrying this patch on recent > chromeos kernels and find it useful. This is a second attempt to try > to get this acceptable, so waiting for your feedback, and I hope I'll be > able to do the modifications needed. > > Changes since v1: > - Use dump_mem() to dump memory. > - Put the code behind a config option. > > [1] http://www.spinics.net/lists/arm-kernel/msg107477.html > --- > arch/arm/include/asm/traps.h | 1 + > arch/arm/kernel/process.c | 34 ++++++++++++++++++++++++++++++++++ > arch/arm/kernel/traps.c | 6 ++---- > lib/Kconfig.debug | 11 +++++++++++ > 4 files changed, 48 insertions(+), 4 deletions(-) > > diff --git a/arch/arm/include/asm/traps.h b/arch/arm/include/asm/traps.h > index f555bb3..24e65c2 100644 > --- a/arch/arm/include/asm/traps.h > +++ b/arch/arm/include/asm/traps.h > @@ -47,6 +47,7 @@ static inline int in_exception_text(unsigned long ptr) > } > > extern void __init early_trap_init(void *); > +extern void dump_mem(const char *lvl, const char *str, unsigned long bottom, > unsigned long top); > extern void dump_backtrace_entry(unsigned long where, unsigned long from, > unsigned long frame); > extern void ptrace_break(struct task_struct *tsk, struct pt_regs *regs); > > diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c > index 939e8b5..3894cf2 100644 > --- a/arch/arm/kernel/process.c > +++ b/arch/arm/kernel/process.c > @@ -34,6 +34,7 @@ > > #include <asm/processor.h> > #include <asm/thread_notify.h> > +#include <asm/traps.h> > #include <asm/stacktrace.h> > #include <asm/system_misc.h> > #include <asm/mach/time.h> > @@ -94,6 +95,37 @@ void arch_cpu_idle_exit(void) > ledtrig_cpu(CPU_LED_IDLE_END); > } > > +/* > + * Dump a block of kernel memory from around the given address > + */ > +static void __show_regs_extra_data(struct pt_regs *regs, int nbytes) > +{ > +#ifdef CONFIG_DEBUG_AROUND_REGS > + struct map_regs { > + unsigned long reg; > + const char *name; > + }; > + struct map_regs map_dump[] = { > + { regs->ARM_pc, "PC " }, { regs->ARM_lr, "LR " }, > + { regs->ARM_sp, "SP " }, { regs->ARM_ip, "IP " }, > + { regs->ARM_fp, "FP " }, { regs->ARM_r0, "R0 " }, > + { regs->ARM_r1, "R1 " }, { regs->ARM_r2, "R2 " }, > + { regs->ARM_r3, "R3 " }, { regs->ARM_r4, "R4 " }, > + { regs->ARM_r5, "R5 " }, { regs->ARM_r6, "R6 " }, > + { regs->ARM_r7, "R7 " }, { regs->ARM_r8, "R8 " }, > + { regs->ARM_r9, "R9 " }, { regs->ARM_r10, "R10 " }, > + { -1, NULL }, > + }; > + struct map_regs *map = map_dump; > + > + while (map->name) { > + dump_mem("", map->name, map->reg - nbytes, > + map->reg + nbytes); > + map++; > + } > +#endif > +} > + > void __show_regs(struct pt_regs *regs) > { > unsigned long flags; > @@ -185,6 +217,8 @@ void __show_regs(struct pt_regs *regs) > printk("Control: %08x%s\n", ctrl, buf); > } > #endif > + > + __show_regs_extra_data(regs, 128); > } > > void show_regs(struct pt_regs * regs) > diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c > index 948c648..f4ee05b 100644 > --- a/arch/arm/kernel/traps.c > +++ b/arch/arm/kernel/traps.c > @@ -62,8 +62,6 @@ static int __init user_debug_setup(char *str) > __setup("user_debug=", user_debug_setup); > #endif > > -static void dump_mem(const char *, const char *, unsigned long, unsigned > long); > - > void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned > long frame) > { > #ifdef CONFIG_KALLSYMS > @@ -115,8 +113,8 @@ static int verify_stack(unsigned long sp) > /* > * Dump out the contents of some memory nicely... > */ > -static void dump_mem(const char *lvl, const char *str, unsigned long bottom, > - unsigned long top) > +void dump_mem(const char *lvl, const char *str, unsigned long bottom, > + unsigned long top) > { > unsigned long first; > mm_segment_t fs; > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 77fadfa..b72d4ce6 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -726,6 +726,17 @@ config DEBUG_STACKOVERFLOW > > If in doubt, say "N". > > +config DEBUG_AROUND_REGS > + bool "Dump a block of kernel memory from around registers" > + depends on DEBUG_KERNEL > + help > + Say Y here to dump a block of kernel memory around the registers > + in the kernel oops dump. This is useful in diagnosing remote > + crashes. > + > + Note that selecting this option will increase significally the > + information in the oops dump. Most people should say N here. > + > source "lib/Kconfig.kmemcheck" > > source "lib/Kconfig.kasan" > -- > 2.9.3 >
Currently this patch might need to be rebased on top of linux-next, but before do this can I ask for some feedback on these patches. Thoughts? Many thanks, Enric
