Q: s390/s390x SIGSEGV SEGV_MAPERR reporting

[Dmitry V. Levin]

On Sat, Feb 28, 2015 at 04:27:21PM -0500, Mike Frysinger wrote:
> i guess we just ignore the failure on s390/s390x and let upstream sort it out.

I was going to apply the following patch but, surprisingly,
it fails on ppc64:

[00001fffffeb61c4] mmap(NULL, 65536, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x1ffffff80000
...
[pid 12345] [0000000010000760] --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_ACCERR, si_addr=0x1ffffff80000} ---

--- a/tests/pc.c
+++ b/tests/pc.c
@@ -1,23 +1,18 @@
-#ifdef HAVE_CONFIG_H
-# include "config.h"
-#endif
-#include <dlfcn.h>
-#include <fcntl.h>
 #include <unistd.h>
 #include <sys/mman.h>
 #include <sys/wait.h>
-#include <sys/sendfile.h>
 
 int main(void)
 {
-	const unsigned long pagesize = sysconf(_SC_PAGESIZE);
+	const unsigned long size = sysconf(_SC_PAGESIZE);
+	void *addr;
 
-	/* write instruction pointer length to the log */
-	if (write(-1, NULL, 2 * sizeof(void *)) >= 0)
+	addr = mmap(NULL, size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (!addr || addr == MAP_FAILED)
 		return 77;
 
-	/* just a noticeable line in the log */
-	if (munmap(&main, 0) >= 0)
+	/* write instruction pointer length to the log */
+	if (write(-1, NULL, 2 * sizeof(void *)) >= 0)
 		return 77;
 
 	int pid = fork();
@@ -25,29 +20,13 @@ int main(void)
 		return 77;
 
 	if (!pid) {
-		const unsigned long mask = ~(pagesize - 1);
-		unsigned long addr = (unsigned long) &main & mask;
-		unsigned long size = pagesize << 1;
+		union {
+			void (*f)(void);
+			void *p;
+		} crash = { .p = addr };
 
-#ifdef HAVE_DLADDR
-		Dl_info info;
-		if (dladdr(&main, &info)) {
-			const unsigned long base =
-				(unsigned long) info.dli_fbase & mask;
-			if (base < addr) {
-				size += addr - base;
-				addr = base;
-			}
-		} else
-#endif
-		{
-			addr -= size;
-			size <<= 1;
-		}
+		crash.f();
 
-		/* SIGSEGV is expected */
-		(void) munmap((void *) addr, size);
-		(void) munmap((void *) addr, size);
 		return 77;
 	}
 
@@ -57,10 +36,5 @@ int main(void)
 	    WTERMSIG(status) != SIGSEGV)
 		return 77;
 
-	/* dump process map for debug purposes */
-	close(0);
-	if (!open("/proc/self/maps", O_RDONLY))
-		(void) sendfile(1, 0, NULL, pagesize);
-
 	return 0;
 }
--- a/tests/pc.test
+++ b/tests/pc.test
@@ -17,13 +17,13 @@ $STRACE $args > "$OUT" 2> "$LOG" || {
 	fail_ "$STRACE $args does not work"
 }
 
-len="$(sed -n 's/^\[[[:xdigit:]]\+\] write(-1, NULL, \([[:digit:]]\{1,2\}\))[[:space:]]\+= -1 .*/\1/p' "$LOG")" &&
+len="$(sed -n 's/^\[[[:xdigit:]]\+\] write(-1, NULL, \([[:digit:]]\{1,2\}\)) \+= -1 .*/\1/p' "$LOG")" &&
 [ -n "$len" ] &&
 pid="$(sed -n 's/^\[[[:xdigit:]]\{'"$len"'\}\] --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_\(KILLED\|DUMPED\), si_pid=\([[:digit:]]\+\), .*/\2/p' "$LOG")" &&
 [ -n "$pid" ] &&
-ip="$(sed -n 's/^\[pid \+'"$pid"'\] \[\([[:xdigit:]]\{'"$len"'\}\)] --- SIGSEGV {.*} ---$/\1/p' "$LOG")" &&
-[ -n "$ip" ] &&
-addr="$(echo "$ip" |sed 's/^0\+//')" &&
+addr="$(sed -n 's/^\[pid \+'"$pid"'\] \[\([[:xdigit:]]\{'"$len"'\}\)] --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_[^,]\+, si_addr=0x[[:xdigit:]]\+} ---$/\1/p' "$LOG")" &&
+[ -n "$addr" ] &&
+addr="$(echo "$addr" |sed 's/^0\+//')" &&
 [ -n "$addr" ] || {
 	cat "$OUT" "$LOG"
 	fail_ "$STRACE $args output mismatch"
@@ -37,8 +37,7 @@ grep_log()
 	}
 }
 
-grep_log '\[[[:xdigit:]]\{'"$len"'\}\] munmap(0x[[:xdigit:]]\+, 0)[[:space:]]\+= -1 .*'
-grep_log '\[pid \+'"$pid"'\] \['"$ip"'\] --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x'"$addr"'} ---'
+grep_log '\[[[:xdigit:]]\+\] [^(]*mmap[^(]*(NULL, [[:digit:]]\+, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) \+= 0x'"$addr"
 grep_log '\[pid \+'"$pid"'\] \[?\{'"$len"'\}\] +++ killed by SIGSEGV\( (core dumped)\)\? +++'
 grep_log '\[?\{'"$len"'\}\] +++ exited with 0 +++'
 

-- 
ldv
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