Commit f8b435bb authored by Rabin Vincent's avatar Rabin Vincent Committed by Russell King

ARM: 7440/1: kprobes: only test 'sub pc, pc, #1b-2b+8-2' on ARMv6

'sub pc, pc, #1b-2b+8-2' results in address<1:0> == '10'.

sub pc, pc, #const (== ADR pc, #const) performs an interworking branch
(BXWritePC()) on ARMv7+ and a simple branch (BranchWritePC()) on earlier
versions.

In ARM state, BXWritePC() is UNPREDICTABLE when address<1:0> == '10'.

In ARM state on ARMv6+, BranchWritePC() ignores address<1:0>.  Before
ARMv6, BranchWritePC() is UNPREDICTABLE if address<1:0> != '00'

So the instruction is UNPREDICTABLE both before and after v6.
Acked-by: default avatarJon Medhurst <tixy@yxit.co.uk>
Signed-off-by: default avatarRabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent fdeb8e35
...@@ -187,8 +187,8 @@ void kprobe_arm_test_cases(void) ...@@ -187,8 +187,8 @@ void kprobe_arm_test_cases(void)
TEST_BF_R ("mov pc, r",0,2f,"") TEST_BF_R ("mov pc, r",0,2f,"")
TEST_BF_RR("mov pc, r",0,2f,", asl r",1,0,"") TEST_BF_RR("mov pc, r",0,2f,", asl r",1,0,"")
TEST_BB( "sub pc, pc, #1b-2b+8") TEST_BB( "sub pc, pc, #1b-2b+8")
#if __LINUX_ARM_ARCH__ >= 6 #if __LINUX_ARM_ARCH__ == 6 && !defined(CONFIG_CPU_V7)
TEST_BB( "sub pc, pc, #1b-2b+8-2") /* UNPREDICTABLE before ARMv6 */ TEST_BB( "sub pc, pc, #1b-2b+8-2") /* UNPREDICTABLE before and after ARMv6 */
#endif #endif
TEST_BB_R( "sub pc, pc, r",14, 1f-2f+8,"") TEST_BB_R( "sub pc, pc, r",14, 1f-2f+8,"")
TEST_BB_R( "rsb pc, r",14,1f-2f+8,", pc") TEST_BB_R( "rsb pc, r",14,1f-2f+8,", pc")
......
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