* [PATCH] ARM: kprobes: Restrict probing SWP instructions to ARMv5 and below
@ 2011-11-27 12:14 Tixy
2011-11-28 16:30 ` Nicolas Pitre
2011-11-30 23:56 ` Russell King - ARM Linux
0 siblings, 2 replies; 4+ messages in thread
From: Tixy @ 2011-11-27 12:14 UTC (permalink / raw)
To: linux-arm-kernel
The SWP instruction is deprecated on ARMv6 and with ARMv7 it will be
UNDEFINED when CONFIG_SWP_EMULATE is selected. In this case, probing a
SWP instruction will cause an oops when the kprobes emulation code
executes an undefined instruction.
As the SWP instruction should be rare or non-existent in kernels for
ARMv6 and later, we can simply avoid these problems by not allowing
probing of these.
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
---
arch/arm/kernel/kprobes-arm.c | 4 +++-
arch/arm/kernel/kprobes-test-arm.c | 25 ++++++++++++++++---------
2 files changed, 19 insertions(+), 10 deletions(-)
diff --git a/arch/arm/kernel/kprobes-arm.c b/arch/arm/kernel/kprobes-arm.c
index 9fe8910..8a30c89 100644
--- a/arch/arm/kernel/kprobes-arm.c
+++ b/arch/arm/kernel/kprobes-arm.c
@@ -519,10 +519,12 @@ static const union decode_item arm_cccc_0000_____1001_table[] = {
static const union decode_item arm_cccc_0001_____1001_table[] = {
/* Synchronization primitives */
+#if __LINUX_ARM_ARCH__ < 6
+ /* Deprecated on ARMv6 and may be UNDEFINED on v7 */
/* SMP/SWPB cccc 0001 0x00 xxxx xxxx xxxx 1001 xxxx */
DECODE_EMULATEX (0x0fb000f0, 0x01000090, emulate_rd12rn16rm0_rwflags_nopc,
REGS(NOPC, NOPC, 0, 0, NOPC)),
-
+#endif
/* LDREX/STREX{,D,B,H} cccc 0001 1xxx xxxx xxxx xxxx 1001 xxxx */
/* And unallocated instructions... */
DECODE_END
diff --git a/arch/arm/kernel/kprobes-test-arm.c b/arch/arm/kernel/kprobes-test-arm.c
index edf9ad8..ba32b39 100644
--- a/arch/arm/kernel/kprobes-test-arm.c
+++ b/arch/arm/kernel/kprobes-test-arm.c
@@ -427,18 +427,25 @@ void kprobe_arm_test_cases(void)
TEST_GROUP("Synchronization primitives")
- /*
- * Use hard coded constants for SWP instructions to avoid warnings
- * about deprecated instructions.
- */
- TEST_RP( ".word 0xe108e097 @ swp lr, r",7,VAL2,", [r",8,0,"]")
- TEST_R( ".word 0x610d0091 @ swpvs r0, r",1,VAL1,", [sp]")
- TEST_RP( ".word 0xe10cd09e @ swp sp, r",14,VAL2,", [r",12,13*4,"]")
+#if __LINUX_ARM_ARCH__ < 6
+ TEST_RP("swp lr, r",7,VAL2,", [r",8,0,"]")
+ TEST_R( "swpvs r0, r",1,VAL1,", [sp]")
+ TEST_RP("swp sp, r",14,VAL2,", [r",12,13*4,"]")
+#else
+ TEST_UNSUPPORTED(".word 0xe108e097 @ swp lr, r7, [r8]")
+ TEST_UNSUPPORTED(".word 0x610d0091 @ swpvs r0, r1, [sp]")
+ TEST_UNSUPPORTED(".word 0xe10cd09e @ swp sp, r14 [r12]")
+#endif
TEST_UNSUPPORTED(".word 0xe102f091 @ swp pc, r1, [r2]")
TEST_UNSUPPORTED(".word 0xe102009f @ swp r0, pc, [r2]")
TEST_UNSUPPORTED(".word 0xe10f0091 @ swp r0, r1, [pc]")
- TEST_RP( ".word 0xe148e097 @ swpb lr, r",7,VAL2,", [r",8,0,"]")
- TEST_R( ".word 0x614d0091 @ swpvsb r0, r",1,VAL1,", [sp]")
+#if __LINUX_ARM_ARCH__ < 6
+ TEST_RP("swpb lr, r",7,VAL2,", [r",8,0,"]")
+ TEST_R( "swpvsb r0, r",1,VAL1,", [sp]")
+#else
+ TEST_UNSUPPORTED(".word 0xe148e097 @ swpb lr, r7, [r8]")
+ TEST_UNSUPPORTED(".word 0x614d0091 @ swpvsb r0, r1, [sp]")
+#endif
TEST_UNSUPPORTED(".word 0xe142f091 @ swpb pc, r1, [r2]")
TEST_UNSUPPORTED(".word 0xe1100090") /* Unallocated space */
--
1.7.2.5
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH] ARM: kprobes: Restrict probing SWP instructions to ARMv5 and below
2011-11-27 12:14 [PATCH] ARM: kprobes: Restrict probing SWP instructions to ARMv5 and below Tixy
@ 2011-11-28 16:30 ` Nicolas Pitre
2011-11-30 23:56 ` Russell King - ARM Linux
1 sibling, 0 replies; 4+ messages in thread
From: Nicolas Pitre @ 2011-11-28 16:30 UTC (permalink / raw)
To: linux-arm-kernel
On Sun, 27 Nov 2011, Tixy wrote:
> The SWP instruction is deprecated on ARMv6 and with ARMv7 it will be
> UNDEFINED when CONFIG_SWP_EMULATE is selected. In this case, probing a
> SWP instruction will cause an oops when the kprobes emulation code
> executes an undefined instruction.
>
> As the SWP instruction should be rare or non-existent in kernels for
> ARMv6 and later, we can simply avoid these problems by not allowing
> probing of these.
>
> Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nico@linaro.org>
> ---
> arch/arm/kernel/kprobes-arm.c | 4 +++-
> arch/arm/kernel/kprobes-test-arm.c | 25 ++++++++++++++++---------
> 2 files changed, 19 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm/kernel/kprobes-arm.c b/arch/arm/kernel/kprobes-arm.c
> index 9fe8910..8a30c89 100644
> --- a/arch/arm/kernel/kprobes-arm.c
> +++ b/arch/arm/kernel/kprobes-arm.c
> @@ -519,10 +519,12 @@ static const union decode_item arm_cccc_0000_____1001_table[] = {
> static const union decode_item arm_cccc_0001_____1001_table[] = {
> /* Synchronization primitives */
>
> +#if __LINUX_ARM_ARCH__ < 6
> + /* Deprecated on ARMv6 and may be UNDEFINED on v7 */
> /* SMP/SWPB cccc 0001 0x00 xxxx xxxx xxxx 1001 xxxx */
> DECODE_EMULATEX (0x0fb000f0, 0x01000090, emulate_rd12rn16rm0_rwflags_nopc,
> REGS(NOPC, NOPC, 0, 0, NOPC)),
> -
> +#endif
> /* LDREX/STREX{,D,B,H} cccc 0001 1xxx xxxx xxxx xxxx 1001 xxxx */
> /* And unallocated instructions... */
> DECODE_END
> diff --git a/arch/arm/kernel/kprobes-test-arm.c b/arch/arm/kernel/kprobes-test-arm.c
> index edf9ad8..ba32b39 100644
> --- a/arch/arm/kernel/kprobes-test-arm.c
> +++ b/arch/arm/kernel/kprobes-test-arm.c
> @@ -427,18 +427,25 @@ void kprobe_arm_test_cases(void)
>
> TEST_GROUP("Synchronization primitives")
>
> - /*
> - * Use hard coded constants for SWP instructions to avoid warnings
> - * about deprecated instructions.
> - */
> - TEST_RP( ".word 0xe108e097 @ swp lr, r",7,VAL2,", [r",8,0,"]")
> - TEST_R( ".word 0x610d0091 @ swpvs r0, r",1,VAL1,", [sp]")
> - TEST_RP( ".word 0xe10cd09e @ swp sp, r",14,VAL2,", [r",12,13*4,"]")
> +#if __LINUX_ARM_ARCH__ < 6
> + TEST_RP("swp lr, r",7,VAL2,", [r",8,0,"]")
> + TEST_R( "swpvs r0, r",1,VAL1,", [sp]")
> + TEST_RP("swp sp, r",14,VAL2,", [r",12,13*4,"]")
> +#else
> + TEST_UNSUPPORTED(".word 0xe108e097 @ swp lr, r7, [r8]")
> + TEST_UNSUPPORTED(".word 0x610d0091 @ swpvs r0, r1, [sp]")
> + TEST_UNSUPPORTED(".word 0xe10cd09e @ swp sp, r14 [r12]")
> +#endif
> TEST_UNSUPPORTED(".word 0xe102f091 @ swp pc, r1, [r2]")
> TEST_UNSUPPORTED(".word 0xe102009f @ swp r0, pc, [r2]")
> TEST_UNSUPPORTED(".word 0xe10f0091 @ swp r0, r1, [pc]")
> - TEST_RP( ".word 0xe148e097 @ swpb lr, r",7,VAL2,", [r",8,0,"]")
> - TEST_R( ".word 0x614d0091 @ swpvsb r0, r",1,VAL1,", [sp]")
> +#if __LINUX_ARM_ARCH__ < 6
> + TEST_RP("swpb lr, r",7,VAL2,", [r",8,0,"]")
> + TEST_R( "swpvsb r0, r",1,VAL1,", [sp]")
> +#else
> + TEST_UNSUPPORTED(".word 0xe148e097 @ swpb lr, r7, [r8]")
> + TEST_UNSUPPORTED(".word 0x614d0091 @ swpvsb r0, r1, [sp]")
> +#endif
> TEST_UNSUPPORTED(".word 0xe142f091 @ swpb pc, r1, [r2]")
>
> TEST_UNSUPPORTED(".word 0xe1100090") /* Unallocated space */
> --
> 1.7.2.5
>
>
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] ARM: kprobes: Restrict probing SWP instructions to ARMv5 and below
2011-11-27 12:14 [PATCH] ARM: kprobes: Restrict probing SWP instructions to ARMv5 and below Tixy
2011-11-28 16:30 ` Nicolas Pitre
@ 2011-11-30 23:56 ` Russell King - ARM Linux
2011-12-01 7:40 ` Tixy
1 sibling, 1 reply; 4+ messages in thread
From: Russell King - ARM Linux @ 2011-11-30 23:56 UTC (permalink / raw)
To: linux-arm-kernel
On Sun, Nov 27, 2011 at 12:14:40PM +0000, Tixy wrote:
> The SWP instruction is deprecated on ARMv6 and with ARMv7 it will be
> UNDEFINED when CONFIG_SWP_EMULATE is selected. In this case, probing a
> SWP instruction will cause an oops when the kprobes emulation code
> executes an undefined instruction.
>
> As the SWP instruction should be rare or non-existent in kernels for
> ARMv6 and later, we can simply avoid these problems by not allowing
> probing of these.
Is this something for -stable stuff?
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] ARM: kprobes: Restrict probing SWP instructions to ARMv5 and below
2011-11-30 23:56 ` Russell King - ARM Linux
@ 2011-12-01 7:40 ` Tixy
0 siblings, 0 replies; 4+ messages in thread
From: Tixy @ 2011-12-01 7:40 UTC (permalink / raw)
To: linux-arm-kernel
On Wed, 2011-11-30 at 23:56 +0000, Russell King - ARM Linux wrote:
> On Sun, Nov 27, 2011 at 12:14:40PM +0000, Tixy wrote:
> > The SWP instruction is deprecated on ARMv6 and with ARMv7 it will be
> > UNDEFINED when CONFIG_SWP_EMULATE is selected. In this case, probing a
> > SWP instruction will cause an oops when the kprobes emulation code
> > executes an undefined instruction.
> >
> > As the SWP instruction should be rare or non-existent in kernels for
> > ARMv6 and later, we can simply avoid these problems by not allowing
> > probing of these.
>
> Is this something for -stable stuff?
It affects 3.1, though in practice I doubt there are any SWP
instructions to probe in an ARMv7 kernel with CONFIG_SWP_EMULATE
enabled. It was only the test code, added to 3.2, that tested the
emulation of SWP instructions and showed up the problem.
--
Tixy
^ permalink raw reply [flat|nested] 4+ messages in thread
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2011-11-27 12:14 [PATCH] ARM: kprobes: Restrict probing SWP instructions to ARMv5 and below Tixy
2011-11-28 16:30 ` Nicolas Pitre
2011-11-30 23:56 ` Russell King - ARM Linux
2011-12-01 7:40 ` Tixy
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