diff options
Diffstat (limited to 'arch/x86/kernel/dumpstack.c')
| -rw-r--r-- | arch/x86/kernel/dumpstack.c | 144 |
1 files changed, 70 insertions, 74 deletions
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 18fa9d74c182..666a284116ac 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -22,11 +22,14 @@ #include <asm/stacktrace.h> #include <asm/unwind.h> +#define OPCODE_BUFSIZE 64 + int panic_on_unrecovered_nmi; int panic_on_io_nmi; -static unsigned int code_bytes = 64; static int die_counter; +static struct pt_regs exec_summary_regs; + bool in_task_stack(unsigned long *stack, struct task_struct *task, struct stack_info *info) { @@ -69,9 +72,62 @@ static void printk_stack_address(unsigned long address, int reliable, printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address); } +/* + * There are a couple of reasons for the 2/3rd prologue, courtesy of Linus: + * + * In case where we don't have the exact kernel image (which, if we did, we can + * simply disassemble and navigate to the RIP), the purpose of the bigger + * prologue is to have more context and to be able to correlate the code from + * the different toolchains better. + * + * In addition, it helps in recreating the register allocation of the failing + * kernel and thus make sense of the register dump. + * + * What is more, the additional complication of a variable length insn arch like + * x86 warrants having longer byte sequence before rIP so that the disassembler + * can "sync" up properly and find instruction boundaries when decoding the + * opcode bytes. + * + * Thus, the 2/3rds prologue and 64 byte OPCODE_BUFSIZE is just a random + * guesstimate in attempt to achieve all of the above. + */ +void show_opcodes(u8 *rip, const char *loglvl) +{ + unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3; + u8 opcodes[OPCODE_BUFSIZE]; + u8 *ip; + int i; + + printk("%sCode: ", loglvl); + + ip = (u8 *)rip - code_prologue; + if (probe_kernel_read(opcodes, ip, OPCODE_BUFSIZE)) { + pr_cont("Bad RIP value.\n"); + return; + } + + for (i = 0; i < OPCODE_BUFSIZE; i++, ip++) { + if (ip == rip) + pr_cont("<%02x> ", opcodes[i]); + else + pr_cont("%02x ", opcodes[i]); + } + pr_cont("\n"); +} + +void show_ip(struct pt_regs *regs, const char *loglvl) +{ +#ifdef CONFIG_X86_32 + printk("%sEIP: %pS\n", loglvl, (void *)regs->ip); +#else + printk("%sRIP: %04x:%pS\n", loglvl, (int)regs->cs, (void *)regs->ip); +#endif + show_opcodes((u8 *)regs->ip, loglvl); +} + void show_iret_regs(struct pt_regs *regs) { - printk(KERN_DEFAULT "RIP: %04x:%pS\n", (int)regs->cs, (void *)regs->ip); + show_ip(regs, KERN_DEFAULT); printk(KERN_DEFAULT "RSP: %04x:%016lx EFLAGS: %08lx", (int)regs->ss, regs->sp, regs->flags); } @@ -267,7 +323,6 @@ unsigned long oops_begin(void) bust_spinlocks(1); return flags; } -EXPORT_SYMBOL_GPL(oops_begin); NOKPROBE_SYMBOL(oops_begin); void __noreturn rewind_stack_do_exit(int signr); @@ -287,6 +342,9 @@ void oops_end(unsigned long flags, struct pt_regs *regs, int signr) raw_local_irq_restore(flags); oops_exit(); + /* Executive summary in case the oops scrolled away */ + __show_regs(&exec_summary_regs, true); + if (!signr) return; if (in_interrupt()) @@ -305,10 +363,10 @@ NOKPROBE_SYMBOL(oops_end); int __die(const char *str, struct pt_regs *regs, long err) { -#ifdef CONFIG_X86_32 - unsigned short ss; - unsigned long sp; -#endif + /* Save the regs of the first oops for the executive summary later. */ + if (!die_counter) + exec_summary_regs = *regs; + printk(KERN_DEFAULT "%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter, IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "", @@ -318,26 +376,13 @@ int __die(const char *str, struct pt_regs *regs, long err) IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ? (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : ""); + show_regs(regs); + print_modules(); + if (notify_die(DIE_OOPS, str, regs, err, current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP) return 1; - print_modules(); - show_regs(regs); -#ifdef CONFIG_X86_32 - if (user_mode(regs)) { - sp = regs->sp; - ss = regs->ss; - } else { - sp = kernel_stack_pointer(regs); - savesegment(ss, ss); - } - printk(KERN_EMERG "EIP: %pS SS:ESP: %04x:%08lx\n", - (void *)regs->ip, ss, sp); -#else - /* Executive summary in case the oops scrolled away */ - printk(KERN_ALERT "RIP: %pS RSP: %016lx\n", (void *)regs->ip, regs->sp); -#endif return 0; } NOKPROBE_SYMBOL(__die); @@ -356,30 +401,9 @@ void die(const char *str, struct pt_regs *regs, long err) oops_end(flags, regs, sig); } -static int __init code_bytes_setup(char *s) -{ - ssize_t ret; - unsigned long val; - - if (!s) - return -EINVAL; - - ret = kstrtoul(s, 0, &val); - if (ret) - return ret; - - code_bytes = val; - if (code_bytes > 8192) - code_bytes = 8192; - - return 1; -} -__setup("code_bytes=", code_bytes_setup); - void show_regs(struct pt_regs *regs) { bool all = true; - int i; show_regs_print_info(KERN_DEFAULT); @@ -389,36 +413,8 @@ void show_regs(struct pt_regs *regs) __show_regs(regs, all); /* - * When in-kernel, we also print out the stack and code at the - * time of the fault.. + * When in-kernel, we also print out the stack at the time of the fault.. */ - if (!user_mode(regs)) { - unsigned int code_prologue = code_bytes * 43 / 64; - unsigned int code_len = code_bytes; - unsigned char c; - u8 *ip; - + if (!user_mode(regs)) show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT); - - printk(KERN_DEFAULT "Code: "); - - ip = (u8 *)regs->ip - code_prologue; - if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) { - /* try starting at IP */ - ip = (u8 *)regs->ip; - code_len = code_len - code_prologue + 1; - } - for (i = 0; i < code_len; i++, ip++) { - if (ip < (u8 *)PAGE_OFFSET || - probe_kernel_address(ip, c)) { - pr_cont(" Bad RIP value."); - break; - } - if (ip == (u8 *)regs->ip) - pr_cont("<%02x> ", c); - else - pr_cont("%02x ", c); - } - } - pr_cont("\n"); } |