diff options
| -rw-r--r-- | tools/objtool/Build | 1 | ||||
| -rw-r--r-- | tools/objtool/include/objtool/objtool.h | 2 | ||||
| -rw-r--r-- | tools/objtool/objtool.c | 4 | ||||
| -rw-r--r-- | tools/objtool/signal.c | 135 |
4 files changed, 141 insertions, 1 deletions
diff --git a/tools/objtool/Build b/tools/objtool/Build index 9982e665d58d..600da051af12 100644 --- a/tools/objtool/Build +++ b/tools/objtool/Build @@ -18,6 +18,7 @@ objtool-y += libstring.o objtool-y += libctype.o objtool-y += str_error_r.o objtool-y += librbtree.o +objtool-y += signal.o $(OUTPUT)libstring.o: ../lib/string.c FORCE $(call rule_mkdir) diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h index f7051bbe0bcb..6dc12a59ad00 100644 --- a/tools/objtool/include/objtool/objtool.h +++ b/tools/objtool/include/objtool/objtool.h @@ -41,6 +41,8 @@ struct objtool_file { char *top_level_dir(const char *file); +int init_signal_handler(void); + struct objtool_file *objtool_open_read(const char *_objname); int objtool_pv_add(struct objtool_file *file, int idx, struct symbol *func); diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c index 3c26ed561c7e..1c3622117c33 100644 --- a/tools/objtool/objtool.c +++ b/tools/objtool/objtool.c @@ -104,11 +104,13 @@ char *top_level_dir(const char *file) return str; } - int main(int argc, const char **argv) { static const char *UNUSED = "OBJTOOL_NOT_IMPLEMENTED"; + if (init_signal_handler()) + return -1; + /* libsubcmd init */ exec_cmd_init("objtool", UNUSED, UNUSED, UNUSED); pager_init(UNUSED); diff --git a/tools/objtool/signal.c b/tools/objtool/signal.c new file mode 100644 index 000000000000..af5c65c0fb2d --- /dev/null +++ b/tools/objtool/signal.c @@ -0,0 +1,135 @@ +/* + * signal.c: Register a sigaltstack for objtool, to be able to + * run a signal handler on a separate stack even if + * the main process stack has overflown. Print out + * stack overflow errors when this happens. + */ +#include <stdio.h> +#include <stdlib.h> +#include <signal.h> +#include <unistd.h> +#include <sys/resource.h> +#include <string.h> + +#include <objtool/objtool.h> +#include <objtool/warn.h> + +static unsigned long stack_limit; + +static bool is_stack_overflow(void *fault_addr) +{ + unsigned long fault = (unsigned long)fault_addr; + + /* Check if fault is in the guard page just below the limit. */ + return fault < stack_limit && fault >= stack_limit - 4096; +} + +static void signal_handler(int sig_num, siginfo_t *info, void *context) +{ + struct sigaction sa_dfl = {0}; + const char *sig_name; + char msg[256]; + int msg_len; + + switch (sig_num) { + case SIGSEGV: sig_name = "SIGSEGV"; break; + case SIGBUS: sig_name = "SIGBUS"; break; + case SIGILL: sig_name = "SIGILL"; break; + case SIGABRT: sig_name = "SIGABRT"; break; + default: sig_name = "Unknown signal"; break; + } + + if (is_stack_overflow(info->si_addr)) { + msg_len = snprintf(msg, sizeof(msg), + "%s: error: %s: objtool stack overflow!\n", + objname, sig_name); + } else { + msg_len = snprintf(msg, sizeof(msg), + "%s: error: %s: objtool crash!\n", + objname, sig_name); + } + + msg_len = write(STDERR_FILENO, msg, msg_len); + + /* Re-raise the signal to trigger the core dump */ + sa_dfl.sa_handler = SIG_DFL; + sigaction(sig_num, &sa_dfl, NULL); + raise(sig_num); +} + +static int read_stack_limit(void) +{ + unsigned long stack_start, stack_end; + struct rlimit rlim; + char line[256]; + int ret = 0; + FILE *fp; + + if (getrlimit(RLIMIT_STACK, &rlim)) { + ERROR_GLIBC("getrlimit"); + return -1; + } + + fp = fopen("/proc/self/maps", "r"); + if (!fp) { + ERROR_GLIBC("fopen"); + return -1; + } + + while (fgets(line, sizeof(line), fp)) { + if (strstr(line, "[stack]")) { + if (sscanf(line, "%lx-%lx", &stack_start, &stack_end) != 2) { + ERROR_GLIBC("sscanf"); + ret = -1; + goto done; + } + stack_limit = stack_end - rlim.rlim_cur; + goto done; + } + } + + ret = -1; + ERROR("/proc/self/maps: can't find [stack]"); + +done: + fclose(fp); + + return ret; +} + +int init_signal_handler(void) +{ + int signals[] = {SIGSEGV, SIGBUS, SIGILL, SIGABRT}; + struct sigaction sa; + stack_t ss; + + if (read_stack_limit()) + return -1; + + ss.ss_sp = malloc(SIGSTKSZ); + if (!ss.ss_sp) { + ERROR_GLIBC("malloc"); + return -1; + } + ss.ss_size = SIGSTKSZ; + ss.ss_flags = 0; + + if (sigaltstack(&ss, NULL) == -1) { + ERROR_GLIBC("sigaltstack"); + return -1; + } + + sa.sa_sigaction = signal_handler; + sigemptyset(&sa.sa_mask); + + sa.sa_flags = SA_ONSTACK | SA_SIGINFO; + + for (int i = 0; i < ARRAY_SIZE(signals); i++) { + if (sigaction(signals[i], &sa, NULL) == -1) { + ERROR_GLIBC("sigaction"); + return -1; + } + } + + return 0; +} |