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ATF test for SIGBUS => BUS_ADRALN (invalid address alignment). 

That one is tedious to test under x86: alignment exceptions are
not reported by this architecture unless you ask for them explicitely (by
setting the PSL_AC bit). The brokenness does not end there: %cr2 should
contain the address where the unaligned access occured, alas, it does not.

I am not aware of other architectures where this could happen. Still, my
knowledge is limited; if there is one, feel free to send me a mail and I
will update the test accordingly.

Adding insult to injury, this test can fail in various funny ways with VMs:
- under x86 QEMU, no trap() happens. As ring 3 code stays almost untouched by
QEMU VMM, I suppose the exception can only be triggered when the host
itself is capable of catching unaligned accesses.
- under Virtual Box with HVM support, i386 works fine, but amd64 fails with a
SIGILL (Illegal instruction) that happens right before entering the
signal handler. No idea why, and trying to debug it with gdb freezes the VM
(including ddb breaks).

Anyway, tested with:
- i386: P4 host, anita, Virtual Box HVM (Mac OS X)
- amd64: anita, Virtual Box HVM (Mac OS X)

XXX I would appreciate if someone could test it under a real amd64 host with
an up-to-date kernel, so I can reasonably assume that the culprit is
Virtual Box and not our amd64 port (my test machine being off line
I cannot do it myself). Results from other arches would be a plus too.

Initial issue reported by Nicolas Joly on port-amd64. Thanks!
This commit is contained in:
jym 2012-04-20 00:40:31 +00:00
parent f90c9c2dab
commit c5252d3225
1 changed files with 69 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

70
tests/lib/libc/gen/t_siginfo.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: t_siginfo.c,v 1.14 2012/03/18 07:14:08 jruoho Exp $ */
/* $NetBSD: t_siginfo.c,v 1.15 2012/04/20 00:40:31 jym Exp $ */
/*-
* Copyright (c) 2010 The NetBSD Foundation, Inc.
@ -48,6 +48,9 @@
#include <ieeefp.h>
#endif
/* for sigbus */
char *addr;
/* for sigchild */
pid_t child;
int code;
@ -405,6 +408,70 @@ ATF_TC_BODY(sigsegv, tc)
atf_tc_fail("Test did not fault as expected");
}
static void
sigbus_action(int signo, siginfo_t *info, void *ptr)
{
sig_debug(signo, info, (ucontext_t *)ptr);
ATF_REQUIRE_EQ(info->si_signo, SIGBUS);
ATF_REQUIRE_EQ(info->si_errno, 0);
ATF_REQUIRE_EQ(info->si_code, BUS_ADRALN);
if (strcmp(atf_config_get("atf_arch"), "i386") == 0 ||
strcmp(atf_config_get("atf_arch"), "x86_64") == 0) {
atf_tc_expect_fail("x86 architecture does not correctly "
"report the address where the unaligned access occured");
}
ATF_REQUIRE_EQ(info->si_addr, (void *)addr);
atf_tc_pass();
/* NOTREACHED */
}
ATF_TC(sigbus_adraln);
ATF_TC_HEAD(sigbus_adraln, tc)
{
atf_tc_set_md_var(tc, "descr",
"Checks that signal trampoline correctly calls SIGBUS handler "
"for invalid address alignment");
}
ATF_TC_BODY(sigbus_adraln, tc)
{
struct sigaction sa;
sa.sa_flags = SA_SIGINFO;
sa.sa_sigaction = sigbus_action;
sigemptyset(&sa.sa_mask);
sigaction(SIGBUS, &sa, NULL);
/* Enable alignement checks for x86. 0x40000 is PSL_AC. */
#if defined(__i386__)
__asm__("pushf; orl $0x40000, (%esp); popf");
#elif defined(__amd64__)
__asm__("pushf; orl $0x40000, (%rsp); popf");
#endif
addr = calloc(2, sizeof(int));
ATF_REQUIRE(addr != NULL);
if (strcmp(atf_config_get("atf_arch"), "i386") == 0 ||
strcmp(atf_config_get("atf_arch"), "x86_64") == 0) {
if (system("cpuctl identify 0 | grep -q QEMU") == 0) {
atf_tc_expect_fail("QEMU fails to trap unaligned "
"accesses");
}
}
/* Force an unaligned access */
addr++;
ATF_REQUIRE_EQ(*(volatile int *)addr, 0);
atf_tc_fail("Test did not fault as expected");
}
ATF_TP_ADD_TCS(tp)
{
@ -415,6 +482,7 @@ ATF_TP_ADD_TCS(tp)
ATF_TP_ADD_TC(tp, sigfpe_flt);
ATF_TP_ADD_TC(tp, sigfpe_int);
ATF_TP_ADD_TC(tp, sigsegv);
ATF_TP_ADD_TC(tp, sigbus_adraln);
return atf_no_error();
}