Log signal info at time of receipt
When a fatal signal is received, we now write a message to the log
that looks like this:
F/libc ( 1540): Fatal signal 11 (SIGSEGV) at 0xdeadd00d (code=1)
This is useful for debugging fatal signals that turn out not to be
fatal. This also changes the signal reset from SIG_IGN to SIG_DFL,
so that future non-fatal fatal signals are fatal.
The code that blocked SIGUSR1 to avoid being interrupted by the GC
has been removed.
Also, fix minor issues in format_buffer().
Bug 5035703
Change-Id: I8940af47297b5dcf3cf33537e3483ca5334ed565
diff --git a/linker/debugger.c b/linker/debugger.c
index abb383c..648dc78 100644
--- a/linker/debugger.c
+++ b/linker/debugger.c
@@ -87,13 +87,49 @@
return s;
}
-void debugger_signal_handler(int n)
+#include "linker_format.h"
+#include <../libc/private/logd.h>
+
+/*
+ * Writes a summary of the signal to the log file.
+ *
+ * We could be here as a result of native heap corruption, or while a
+ * mutex is being held, so we don't want to use any libc functions that
+ * could allocate memory or hold a lock.
+ */
+static void logSignalSummary(int signum, const siginfo_t* info)
+{
+ char buffer[128];
+
+ char* signame;
+ switch (signum) {
+ case SIGILL: signame = "SIGILL"; break;
+ case SIGABRT: signame = "SIGABRT"; break;
+ case SIGBUS: signame = "SIGBUS"; break;
+ case SIGFPE: signame = "SIGFPE"; break;
+ case SIGSEGV: signame = "SIGSEGV"; break;
+ case SIGSTKFLT: signame = "SIGSTKFLT"; break;
+ case SIGPIPE: signame = "SIGPIPE"; break;
+ default: signame = "???"; break;
+ }
+
+ format_buffer(buffer, sizeof(buffer),
+ "Fatal signal %d (%s) at 0x%08x (code=%d)",
+ signum, signame, info->si_addr, info->si_code);
+
+ __libc_android_log_write(ANDROID_LOG_FATAL, "libc", buffer);
+}
+
+/*
+ * Catches fatal signals so we can ask debuggerd to ptrace us before
+ * we crash.
+ */
+void debugger_signal_handler(int n, siginfo_t* info, void* unused)
{
unsigned tid;
int s;
- /* avoid picking up GC interrupts */
- signal(SIGUSR1, SIG_IGN);
+ logSignalSummary(n, info);
tid = gettid();
s = socket_abstract_client("android:debuggerd", SOCK_STREAM);
@@ -117,16 +153,22 @@
}
/* remove our net so we fault for real when we return */
- signal(n, SIG_IGN);
+ signal(n, SIG_DFL);
}
void debugger_init()
{
- signal(SIGILL, debugger_signal_handler);
- signal(SIGABRT, debugger_signal_handler);
- signal(SIGBUS, debugger_signal_handler);
- signal(SIGFPE, debugger_signal_handler);
- signal(SIGSEGV, debugger_signal_handler);
- signal(SIGSTKFLT, debugger_signal_handler);
- signal(SIGPIPE, debugger_signal_handler);
+ struct sigaction act;
+ memset(&act, 0, sizeof(act));
+ act.sa_sigaction = debugger_signal_handler;
+ act.sa_flags = SA_RESTART | SA_SIGINFO;
+ sigemptyset(&act.sa_mask);
+
+ sigaction(SIGILL, &act, NULL);
+ sigaction(SIGABRT, &act, NULL);
+ sigaction(SIGBUS, &act, NULL);
+ sigaction(SIGFPE, &act, NULL);
+ sigaction(SIGSEGV, &act, NULL);
+ sigaction(SIGSTKFLT, &act, NULL);
+ sigaction(SIGPIPE, &act, NULL);
}
diff --git a/linker/linker_format.c b/linker/linker_format.c
index 4d00bd9..0c68a0b 100644
--- a/linker/linker_format.c
+++ b/linker/linker_format.c
@@ -427,18 +427,20 @@
static void
out_vformat(Out *o, const char *format, va_list args)
{
- int nn = 0, mm;
- int padZero = 0;
- int padLeft = 0;
- char sign = '\0';
- int width = -1;
- int prec = -1;
- size_t bytelen = sizeof(int);
- const char* str;
- int slen;
- char buffer[32]; /* temporary buffer used to format numbers */
+ int nn = 0;
for (;;) {
+ int mm;
+ int padZero = 0;
+ int padLeft = 0;
+ char sign = '\0';
+ int width = -1;
+ int prec = -1;
+ size_t bytelen = sizeof(int);
+ const char* str;
+ int slen;
+ char buffer[32]; /* temporary buffer used to format numbers */
+
char c;
/* first, find all characters that are not 0 or '%' */
@@ -525,9 +527,6 @@
bytelen = sizeof(ptrdiff_t);
c = format[nn++];
break;
- case 'p':
- bytelen = sizeof(void*);
- c = format[nn++];
default:
;
}
@@ -543,7 +542,7 @@
buffer[1] = '\0';
str = buffer;
} else if (c == 'p') {
- uint64_t value = (uint64_t)(ptrdiff_t) va_arg(args, void*);
+ uint64_t value = (uintptr_t) va_arg(args, void*);
buffer[0] = '0';
buffer[1] = 'x';
format_hex(buffer + 2, sizeof buffer-2, value, 0);
@@ -684,7 +683,7 @@
utest_expect("-8123", "%d", -8123);
utest_expect("16", "%hd", 0x7fff0010);
utest_expect("16", "%hhd", 0x7fffff10);
- utest_expect("68719476736", "%lld", 0x1000000000);
+ utest_expect("68719476736", "%lld", 0x1000000000LL);
utest_expect("70000", "%ld", 70000);
utest_expect("0xb0001234", "%p", (void*)0xb0001234);
utest_expect("12ab", "%x", 0x12ab);
@@ -697,6 +696,9 @@
utest_expect("1234 ", "%-8d", 1234);
utest_expect("abcdef ", "%-11s", "abcdef");
utest_expect("something:1234", "%s:%d", "something", 1234);
+ utest_expect("005:5:05", "%03d:%d:%02d", 5, 5, 5);
+ utest_expect("5,0x0", "%d,%p", 5, NULL);
+ utest_expect("68719476736,6,7,8", "%lld,%d,%d,%d", 0x1000000000LL, 6, 7, 8);
return gFails != 0;
}