da2b2da6a
Denys Vlasenko
2012-01-30
Subject
init: add a segv debugging aid, disabled by default
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init/init.c+51 -0
| @@ -108,6 +108,8 @@ | |
| //config: Note that on Linux, init attempts to detect serial terminal and | |
| //config: sets TERM to "vt102" if one is found. | |
| + | #define DEBUG_SEGV_HANDLER 0 |
| + | |
| #include "libbb.h" | |
| #include <syslog.h> | |
| #include <paths.h> | |
| @@ -118,6 +120,15 @@ | |
| #endif | |
| #include "reboot.h" /* reboot() constants */ | |
| + | #if DEBUG_SEGV_HANDLER |
| + | # undef _GNU_SOURCE |
| + | # define _GNU_SOURCE 1 |
| + | # undef __USE_GNU |
| + | # define __USE_GNU 1 |
| + | # include <execinfo.h> |
| + | # include <sys/ucontext.h> |
| + | #endif |
| + | |
| /* Used only for sanitizing purposes in set_sane_term() below. On systems where | |
| * the baud rate is stored in a separate field, we can safely disable them. */ | |
| #ifndef CBAUD | |
| @@ -957,6 +968,33 @@ static int check_delayed_sigs(void) | |
| } | |
| } | |
| + | #if DEBUG_SEGV_HANDLER |
| + | static |
| + | void handle_sigsegv(int sig, siginfo_t *info, void *ucontext) |
| + | { |
| + | long ip; |
| + | ucontext_t *uc; |
| + | |
| + | uc = ucontext; |
| + | ip = uc->uc_mcontext.gregs[REG_EIP]; |
| + | fdprintf(2, "signal:%d address:0x%lx ip:0x%lx\n", |
| + | sig, |
| + | /* this is void*, but using %p would print "(null)" |
| + | * even for ptrs which are not exactly 0, but, say, 0x123: |
| + | */ |
| + | (long)info->si_addr, |
| + | ip); |
| + | { |
| + | /* glibc extension */ |
| + | void *array[50]; |
| + | int size; |
| + | size = backtrace(array, 50); |
| + | backtrace_symbols_fd(array, size, 2); |
| + | } |
| + | for (;;) sleep(9999); |
| + | } |
| + | #endif |
| + | |
| int init_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; | |
| int init_main(int argc UNUSED_PARAM, char **argv) | |
| { | |
| @@ -964,6 +1002,19 @@ int init_main(int argc UNUSED_PARAM, char **argv) | |
| return kill(1, SIGHUP); | |
| } | |
| + | #if DEBUG_SEGV_HANDLER |
| + | { |
| + | struct sigaction sa; |
| + | memset(&sa, 0, sizeof(sa)); |
| + | sa.sa_sigaction = handle_sigsegv; |
| + | sa.sa_flags = SA_SIGINFO; |
| + | sigaction(SIGSEGV, &sa, NULL); |
| + | sigaction(SIGILL, &sa, NULL); |
| + | sigaction(SIGFPE, &sa, NULL); |
| + | sigaction(SIGBUS, &sa, NULL); |
| + | } |
| + | #endif |
| + | |
| if (!DEBUG_INIT) { | |
| /* Expect to be invoked as init with PID=1 or be invoked as linuxrc */ | |
| if (getpid() != 1 | |