[PATCH] ARM: kprobes: Restrict probing SWP instructions to ARMv5 and below
Tixy
tixy at yxit.co.uk
Sun Nov 27 07:14:40 EST 2011
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 at 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
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