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ARM: 7181/1: Restrict kprobes probing SWP instructions to ARMv5 and below

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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.

Reported-by: Leif Lindholm <leif.lindholm@arm.com>
Tested-by: Leif Lindholm <leif.lindholm@arm.com>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Jon Medhurst (Tixy) 2011-11-29 08:16:02 +01:00 committed by Russell King
parent 14383c295a
commit b5bed7fe80
2 changed files with 19 additions and 10 deletions
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4
arch/arm/kernel/kprobes-arm.c
View file

@ -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

25
arch/arm/kernel/kprobes-test-arm.c
View file

@ -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 */