From 571d76acdab95876aeff869ab6449f826c23aa43 Mon Sep 17 00:00:00 2001 From: Chris Metcalf Date: Mon, 16 May 2011 14:23:44 -0400 Subject: [PATCH] arch/tile: support signal "exception-trace" hook This change adds support for /proc/sys/debug/exception-trace to tile. Like x86 and sparc, by default it is set to "1", generating a one-line printk whenever a user process crashes. By setting it to "2", we get a much more complete userspace diagnostic at crash time, including a user-space backtrace, register dump, and memory dump around the address of the crash. Some vestiges of the Tilera-internal version of this support are removed with this patch (the show_crashinfo variable and the arch_coredump_signal function). We retain a "crashinfo" boot parameter which allows you to set the boot-time value of exception-trace. Signed-off-by: Chris Metcalf --- arch/tile/include/asm/processor.h | 7 --- arch/tile/include/asm/signal.h | 4 ++ arch/tile/kernel/compat_signal.c | 4 +- arch/tile/kernel/signal.c | 128 ++++++++++++++++++++++++++++++++++++-- arch/tile/kernel/single_step.c | 4 ++ arch/tile/kernel/traps.c | 1 + arch/tile/mm/fault.c | 24 ++++--- kernel/sysctl.c | 2 +- 8 files changed, 151 insertions(+), 23 deletions(-) diff --git a/arch/tile/include/asm/processor.h b/arch/tile/include/asm/processor.h index d6b43dd..34c1e01 100644 --- a/arch/tile/include/asm/processor.h +++ b/arch/tile/include/asm/processor.h @@ -257,10 +257,6 @@ static inline void cpu_relax(void) barrier(); } -struct siginfo; -extern void arch_coredump_signal(struct siginfo *, struct pt_regs *); -#define arch_coredump_signal arch_coredump_signal - /* Info on this processor (see fs/proc/cpuinfo.c) */ struct seq_operations; extern const struct seq_operations cpuinfo_op; @@ -271,9 +267,6 @@ extern char chip_model[64]; /* Data on which physical memory controller corresponds to which NUMA node. */ extern int node_controller[]; -/* Do we dump information to the console when a user application crashes? */ -extern int show_crashinfo; - #if CHIP_HAS_CBOX_HOME_MAP() /* Does the heap allocator return hash-for-home pages by default? */ extern int hash_default; diff --git a/arch/tile/include/asm/signal.h b/arch/tile/include/asm/signal.h index 81d92a4..1e1e616 100644 --- a/arch/tile/include/asm/signal.h +++ b/arch/tile/include/asm/signal.h @@ -28,6 +28,10 @@ struct pt_regs; int restore_sigcontext(struct pt_regs *, struct sigcontext __user *); int setup_sigcontext(struct sigcontext __user *, struct pt_regs *); void do_signal(struct pt_regs *regs); +void signal_fault(const char *type, struct pt_regs *, + void __user *frame, int sig); +void trace_unhandled_signal(const char *type, struct pt_regs *regs, + unsigned long address, int signo); #endif #endif /* _ASM_TILE_SIGNAL_H */ diff --git a/arch/tile/kernel/compat_signal.c b/arch/tile/kernel/compat_signal.c index dbb0dfc..a7869ad 100644 --- a/arch/tile/kernel/compat_signal.c +++ b/arch/tile/kernel/compat_signal.c @@ -317,7 +317,7 @@ long compat_sys_rt_sigreturn(struct pt_regs *regs) return 0; badframe: - force_sig(SIGSEGV, current); + signal_fault("bad sigreturn frame", regs, frame, 0); return 0; } @@ -431,6 +431,6 @@ int compat_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, return 0; give_sigsegv: - force_sigsegv(sig, current); + signal_fault("bad setup frame", regs, frame, sig); return -EFAULT; } diff --git a/arch/tile/kernel/signal.c b/arch/tile/kernel/signal.c index 1260321..bedaf4e 100644 --- a/arch/tile/kernel/signal.c +++ b/arch/tile/kernel/signal.c @@ -39,7 +39,6 @@ #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) - SYSCALL_DEFINE3(sigaltstack, const stack_t __user *, uss, stack_t __user *, uoss, struct pt_regs *, regs) { @@ -78,6 +77,13 @@ int restore_sigcontext(struct pt_regs *regs, return err; } +void signal_fault(const char *type, struct pt_regs *regs, + void __user *frame, int sig) +{ + trace_unhandled_signal(type, regs, (unsigned long)frame, SIGSEGV); + force_sigsegv(sig, current); +} + /* The assembly shim for this function arranges to ignore the return value. */ SYSCALL_DEFINE1(rt_sigreturn, struct pt_regs *, regs) { @@ -105,7 +111,7 @@ SYSCALL_DEFINE1(rt_sigreturn, struct pt_regs *, regs) return 0; badframe: - force_sig(SIGSEGV, current); + signal_fault("bad sigreturn frame", regs, frame, 0); return 0; } @@ -231,7 +237,7 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, return 0; give_sigsegv: - force_sigsegv(sig, current); + signal_fault("bad setup frame", regs, frame, sig); return -EFAULT; } @@ -245,7 +251,6 @@ static int handle_signal(unsigned long sig, siginfo_t *info, { int ret; - /* Are we from a system call? */ if (regs->faultnum == INT_SWINT_1) { /* If so, check system call restarting.. */ @@ -363,3 +368,118 @@ done: /* Avoid double syscall restart if there are nested signals. */ regs->faultnum = INT_SWINT_1_SIGRETURN; } + +int show_unhandled_signals = 1; + +static int __init crashinfo(char *str) +{ + unsigned long val; + const char *word; + + if (*str == '\0') + val = 2; + else if (*str != '=' || strict_strtoul(++str, 0, &val) != 0) + return 0; + show_unhandled_signals = val; + switch (show_unhandled_signals) { + case 0: + word = "No"; + break; + case 1: + word = "One-line"; + break; + default: + word = "Detailed"; + break; + } + pr_info("%s crash reports will be generated on the console\n", word); + return 1; +} +__setup("crashinfo", crashinfo); + +static void dump_mem(void __user *address) +{ + void __user *addr; + enum { region_size = 256, bytes_per_line = 16 }; + int i, j, k; + int found_readable_mem = 0; + + pr_err("\n"); + if (!access_ok(VERIFY_READ, address, 1)) { + pr_err("Not dumping at address 0x%lx (kernel address)\n", + (unsigned long)address); + return; + } + + addr = (void __user *) + (((unsigned long)address & -bytes_per_line) - region_size/2); + if (addr > address) + addr = NULL; + for (i = 0; i < region_size; + addr += bytes_per_line, i += bytes_per_line) { + unsigned char buf[bytes_per_line]; + char line[100]; + if (copy_from_user(buf, addr, bytes_per_line)) + continue; + if (!found_readable_mem) { + pr_err("Dumping memory around address 0x%lx:\n", + (unsigned long)address); + found_readable_mem = 1; + } + j = sprintf(line, REGFMT":", (unsigned long)addr); + for (k = 0; k < bytes_per_line; ++k) + j += sprintf(&line[j], " %02x", buf[k]); + pr_err("%s\n", line); + } + if (!found_readable_mem) + pr_err("No readable memory around address 0x%lx\n", + (unsigned long)address); +} + +void trace_unhandled_signal(const char *type, struct pt_regs *regs, + unsigned long address, int sig) +{ + struct task_struct *tsk = current; + + if (show_unhandled_signals == 0) + return; + + /* If the signal is handled, don't show it here. */ + if (!is_global_init(tsk)) { + void __user *handler = + tsk->sighand->action[sig-1].sa.sa_handler; + if (handler != SIG_IGN && handler != SIG_DFL) + return; + } + + /* Rate-limit the one-line output, not the detailed output. */ + if (show_unhandled_signals <= 1 && !printk_ratelimit()) + return; + + printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d", + task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, + tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig); + + print_vma_addr(KERN_CONT " in ", regs->pc); + + printk(KERN_CONT "\n"); + + if (show_unhandled_signals > 1) { + switch (sig) { + case SIGILL: + case SIGFPE: + case SIGSEGV: + case SIGBUS: + pr_err("User crash: signal %d," + " trap %ld, address 0x%lx\n", + sig, regs->faultnum, address); + show_regs(regs); + dump_mem((void __user *)address); + break; + default: + pr_err("User crash: signal %d, trap %ld\n", + sig, regs->faultnum); + break; + } + } +} diff --git a/arch/tile/kernel/single_step.c b/arch/tile/kernel/single_step.c index 86df5a23..4032ca8 100644 --- a/arch/tile/kernel/single_step.c +++ b/arch/tile/kernel/single_step.c @@ -186,6 +186,8 @@ static tile_bundle_bits rewrite_load_store_unaligned( .si_code = SEGV_MAPERR, .si_addr = addr }; + trace_unhandled_signal("segfault", regs, + (unsigned long)addr, SIGSEGV); force_sig_info(info.si_signo, &info, current); return (tile_bundle_bits) 0; } @@ -196,6 +198,8 @@ static tile_bundle_bits rewrite_load_store_unaligned( .si_code = BUS_ADRALN, .si_addr = addr }; + trace_unhandled_signal("unaligned trap", regs, + (unsigned long)addr, SIGBUS); force_sig_info(info.si_signo, &info, current); return (tile_bundle_bits) 0; } diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c index 5474fc2..f9803df 100644 --- a/arch/tile/kernel/traps.c +++ b/arch/tile/kernel/traps.c @@ -308,6 +308,7 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num, info.si_addr = (void __user *)address; if (signo == SIGILL) info.si_trapno = fault_num; + trace_unhandled_signal("trap", regs, address, signo); force_sig_info(signo, &info, current); } diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c index 24ca54a..25b7b90 100644 --- a/arch/tile/mm/fault.c +++ b/arch/tile/mm/fault.c @@ -43,8 +43,11 @@ #include -static noinline void force_sig_info_fault(int si_signo, int si_code, - unsigned long address, int fault_num, struct task_struct *tsk) +static noinline void force_sig_info_fault(const char *type, int si_signo, + int si_code, unsigned long address, + int fault_num, + struct task_struct *tsk, + struct pt_regs *regs) { siginfo_t info; @@ -59,6 +62,7 @@ static noinline void force_sig_info_fault(int si_signo, int si_code, info.si_code = si_code; info.si_addr = (void __user *)address; info.si_trapno = fault_num; + trace_unhandled_signal(type, regs, address, si_signo); force_sig_info(si_signo, &info, tsk); } @@ -71,11 +75,12 @@ SYSCALL_DEFINE2(cmpxchg_badaddr, unsigned long, address, struct pt_regs *, regs) { if (address >= PAGE_OFFSET) - force_sig_info_fault(SIGSEGV, SEGV_MAPERR, address, - INT_DTLB_MISS, current); + force_sig_info_fault("atomic segfault", SIGSEGV, SEGV_MAPERR, + address, INT_DTLB_MISS, current, regs); else - force_sig_info_fault(SIGBUS, BUS_ADRALN, address, - INT_UNALIGN_DATA, current); + force_sig_info_fault("atomic alignment fault", SIGBUS, + BUS_ADRALN, address, + INT_UNALIGN_DATA, current, regs); /* * Adjust pc to point at the actual instruction, which is unusual @@ -471,8 +476,8 @@ bad_area_nosemaphore: */ local_irq_enable(); - force_sig_info_fault(SIGSEGV, si_code, address, - fault_num, tsk); + force_sig_info_fault("segfault", SIGSEGV, si_code, address, + fault_num, tsk, regs); return 0; } @@ -547,7 +552,8 @@ do_sigbus: if (is_kernel_mode) goto no_context; - force_sig_info_fault(SIGBUS, BUS_ADRERR, address, fault_num, tsk); + force_sig_info_fault("bus error", SIGBUS, BUS_ADRERR, address, + fault_num, tsk, regs); return 0; } diff --git a/kernel/sysctl.c b/kernel/sysctl.c index c0bb324..aaec934 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1496,7 +1496,7 @@ static struct ctl_table fs_table[] = { static struct ctl_table debug_table[] = { #if defined(CONFIG_X86) || defined(CONFIG_PPC) || defined(CONFIG_SPARC) || \ - defined(CONFIG_S390) + defined(CONFIG_S390) || defined(CONFIG_TILE) { .procname = "exception-trace", .data = &show_unhandled_signals, -- 2.7.4