[PATCH 5.9 415/757] selftests/powerpc: Fix prefixes in alignment_handler signal handler

Greg Kroah-Hartman
2020-10-27T15:56:50Z

From: Jordan Niethe <jniethe5@gmail.com>

[ Upstream commit db96221a683342fd4775fd820a4d5376cd2f2ed0 ]

The signal handler in the alignment handler self test has the ability
to jump over the instruction that triggered the signal. It does this
by incrementing the PT_NIP in the user context by 4. If it were a
prefixed instruction this will mean that the suffix is then executed
which is incorrect. Instead check if the major opcode indicates a
prefixed instruction (e.g. it is 1) and if so increment PT_NIP by 8.

If ISA v3.1 is not available treat it as a word instruction even if
the major opcode is 1.

Fixes: 620a6473df36 ("selftests/powerpc: Add prefixed loads/stores to alignment_handler test")
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
[mpe: Fix 32-bit build, rename haveprefixes to prefixes_enabled]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200824131231.14008-1-jniethe5@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../selftests/powerpc/alignment/alignment_handler.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/powerpc/alignment/alignment_handler.c b/tools/testing/selftests/powerpc/alignment/alignment_handler.c
index 55ef15184057d..386bca731e581 100644
--- a/tools/testing/selftests/powerpc/alignment/alignment_handler.c
+++ b/tools/testing/selftests/powerpc/alignment/alignment_handler.c
@@ -64,6 +64,7 @@ int bufsize;
int debug;
int testing;
volatile int gotsig;
+bool prefixes_enabled;
char *cipath = "/dev/fb0";
long cioffset;

@@ -77,7 +78,12 @@ void sighandler(int sig, siginfo_t *info, void *ctx)
}
gotsig = sig;
#ifdef __powerpc64__
- ucp->uc_mcontext.gp_regs[PT_NIP] += 4;
+ if (prefixes_enabled) {
+ u32 inst = *(u32 *)ucp->uc_mcontext.gp_regs[PT_NIP];
+ ucp->uc_mcontext.gp_regs[PT_NIP] += ((inst >> 26 == 1) ? 8 : 4);
+ } else {
+ ucp->uc_mcontext.gp_regs[PT_NIP] += 4;
+ }
#else
ucp->uc_mcontext.uc_regs->gregs[PT_NIP] += 4;
#endif
@@ -648,6 +654,8 @@ int main(int argc, char *argv[])
exit(1);
}

+ prefixes_enabled = have_hwcap2(PPC_FEATURE2_ARCH_3_1);
+
rc |= test_harness(test_alignment_handler_vsx_206,
"test_alignment_handler_vsx_206");
rc |= test_harness(test_alignment_handler_vsx_207,
--
2.25.1