* [PATCH 2/3] powerpc/64s: Use EMIT_WARN_ENTRY for SRR debug warnings
2021-12-21 13:50 [PATCH 1/3] powerpc/64s: Mask NIP before checking against SRR0 Michael Ellerman
@ 2021-12-21 13:51 ` Michael Ellerman
2021-12-21 13:51 ` [PATCH 3/3] selftests/powerpc: Add a test of sigreturning to an unaligned address Michael Ellerman
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Michael Ellerman @ 2021-12-21 13:51 UTC (permalink / raw)
To: linuxppc-dev; +Cc: sachinp, npiggin
When CONFIG_PPC_RFI_SRR_DEBUG=y we check the SRR values before returning
from interrupts. This is done in asm using EMIT_BUG_ENTRY, and passing
BUGFLAG_WARNING.
However that fails to create an exception table entry for the warning,
and so do_program_check() fails the exception table search and proceeds
to call _exception(), resulting in an oops like:
Oops: Exception in kernel mode, sig: 5 [#1]
LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
Modules linked in:
CPU: 2 PID: 1204 Comm: sigreturn_unali Tainted: P 5.16.0-rc2-00194-g91ca3d4f77c5 #12
NIP: c00000000000c5b0 LR: 0000000000000000 CTR: 0000000000000000
...
NIP [c00000000000c5b0] system_call_common+0x150/0x268
LR [0000000000000000] 0x0
Call Trace:
[c00000000db73e10] [c00000000000c558] system_call_common+0xf8/0x268 (unreliable)
...
Instruction dump:
7cc803a6 888d0931 2c240000 4082001c 38800000 988d0931 e8810170 e8a10178
7c9a03a6 7cbb03a6 7d7a02a6 e9810170 <7f0b6088> 7d7b02a6 e9810178 7f0b6088
We should instead use EMIT_WARN_ENTRY, which creates an exception table
entry for the warning, allowing the warning to be correctly recognised,
and the code to resume after printing the warning.
Note however that because this warning is buried deep in the interrupt
return path, we are not able to recover from it (due to MSR_RI being
clear), so we still end up in die() with an unrecoverable exception.
Fixes: 59dc5bfca0cb ("powerpc/64s: avoid reloading (H)SRR registers if they are still valid")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/kernel/interrupt_64.S | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/interrupt_64.S
index 4fd65d39d5d3..be5ff1521505 100644
--- a/arch/powerpc/kernel/interrupt_64.S
+++ b/arch/powerpc/kernel/interrupt_64.S
@@ -32,21 +32,21 @@
ld r12,_NIP(r1)
clrrdi r12,r12,2
100: tdne r11,r12
- EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
+ EMIT_WARN_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
mfspr r11,SPRN_SRR1
ld r12,_MSR(r1)
100: tdne r11,r12
- EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
+ EMIT_WARN_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
.else
mfspr r11,SPRN_HSRR0
ld r12,_NIP(r1)
clrrdi r12,r12,2
100: tdne r11,r12
- EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
+ EMIT_WARN_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
mfspr r11,SPRN_HSRR1
ld r12,_MSR(r1)
100: tdne r11,r12
- EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
+ EMIT_WARN_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
.endif
#endif
.endm
--
2.31.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH 3/3] selftests/powerpc: Add a test of sigreturning to an unaligned address
2021-12-21 13:50 [PATCH 1/3] powerpc/64s: Mask NIP before checking against SRR0 Michael Ellerman
2021-12-21 13:51 ` [PATCH 2/3] powerpc/64s: Use EMIT_WARN_ENTRY for SRR debug warnings Michael Ellerman
@ 2021-12-21 13:51 ` Michael Ellerman
2021-12-22 10:25 ` [PATCH 1/3] powerpc/64s: Mask NIP before checking against SRR0 Sachin Sant
2021-12-26 21:52 ` Michael Ellerman
3 siblings, 0 replies; 5+ messages in thread
From: Michael Ellerman @ 2021-12-21 13:51 UTC (permalink / raw)
To: linuxppc-dev; +Cc: sachinp, npiggin
Add a test of sigreturning to an unaligned address (low two bits set).
This should have no effect because the hardware will mask those bits.
However it previously falsely triggered a warning when
CONFIG_PPC_RFI_SRR_DEBUG=y.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
.../selftests/powerpc/signal/.gitignore | 1 +
.../testing/selftests/powerpc/signal/Makefile | 1 +
.../powerpc/signal/sigreturn_unaligned.c | 43 +++++++++++++++++++
3 files changed, 45 insertions(+)
create mode 100644 tools/testing/selftests/powerpc/signal/sigreturn_unaligned.c
diff --git a/tools/testing/selftests/powerpc/signal/.gitignore b/tools/testing/selftests/powerpc/signal/.gitignore
index 8f6c816099a4..9d0915777fed 100644
--- a/tools/testing/selftests/powerpc/signal/.gitignore
+++ b/tools/testing/selftests/powerpc/signal/.gitignore
@@ -5,3 +5,4 @@ sigfuz
sigreturn_vdso
sig_sc_double_restart
sigreturn_kernel
+sigreturn_unaligned
diff --git a/tools/testing/selftests/powerpc/signal/Makefile b/tools/testing/selftests/powerpc/signal/Makefile
index 84e201572466..f679d260afc8 100644
--- a/tools/testing/selftests/powerpc/signal/Makefile
+++ b/tools/testing/selftests/powerpc/signal/Makefile
@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
TEST_GEN_PROGS := signal signal_tm sigfuz sigreturn_vdso sig_sc_double_restart
TEST_GEN_PROGS += sigreturn_kernel
+TEST_GEN_PROGS += sigreturn_unaligned
CFLAGS += -maltivec
$(OUTPUT)/signal_tm: CFLAGS += -mhtm
diff --git a/tools/testing/selftests/powerpc/signal/sigreturn_unaligned.c b/tools/testing/selftests/powerpc/signal/sigreturn_unaligned.c
new file mode 100644
index 000000000000..6e58ee4f0fdf
--- /dev/null
+++ b/tools/testing/selftests/powerpc/signal/sigreturn_unaligned.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test sigreturn to an unaligned address, ie. low 2 bits set.
+ * Nothing bad should happen.
+ * This was able to trigger warnings with CONFIG_PPC_RFI_SRR_DEBUG=y.
+ */
+
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ucontext.h>
+#include <unistd.h>
+
+#include "utils.h"
+
+
+static void sigusr1_handler(int signo, siginfo_t *info, void *ptr)
+{
+ ucontext_t *uc = ptr;
+
+ UCONTEXT_NIA(uc) |= 3;
+}
+
+static int test_sigreturn_unaligned(void)
+{
+ struct sigaction action;
+
+ memset(&action, 0, sizeof(action));
+ action.sa_sigaction = sigusr1_handler;
+ action.sa_flags = SA_SIGINFO;
+
+ FAIL_IF(sigaction(SIGUSR1, &action, NULL) == -1);
+
+ raise(SIGUSR1);
+
+ return 0;
+}
+
+int main(void)
+{
+ return test_harness(test_sigreturn_unaligned, "sigreturn_unaligned");
+}
--
2.31.1
^ permalink raw reply related [flat|nested] 5+ messages in thread