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ARM: 7299/1: ftrace: clear zero bit in reported IPs for Thumb-2

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The dynamic ftrace ops startup test currently fails on Thumb-2 kernels:

 Testing tracer function: PASSED
 Testing dynamic ftrace: PASSED
 Testing dynamic ftrace ops #1: (0 0 0 0 0) FAILED!

This is because while the addresses in the mcount records do not have
the zero bit set, the IP reported by the mcount call does have it set
(because it is copied from the LR).  This mismatch causes the ops
filtering in ftrace_ops_list_func() to not call the relevant tracers.

Fix this by clearing the zero bit before adjusting the LR for the mcount
instruction size.  Also, combine the mov+sub into a single sub
instruction.

Acked-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Rabin Vincent 2012-01-24 16:52:52 +01:00 committed by Russell King
parent 34ae6c96a6
commit d68133b5a8
1 changed files with 9 additions and 6 deletions
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15
arch/arm/kernel/entry-common.S
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@ -149,6 +149,11 @@ ENDPROC(ret_from_fork)
#endif
#endif
.macro mcount_adjust_addr rd, rn
bic \rd, \rn, #1 @ clear the Thumb bit if present
sub \rd, \rd, #MCOUNT_INSN_SIZE
.endm
.macro __mcount suffix
mcount_enter
ldr r0, =ftrace_trace_function
@ -173,8 +178,7 @@ ENDPROC(ret_from_fork)
mcount_exit
1: mcount_get_lr r1 @ lr of instrumented func
mov r0, lr @ instrumented function
sub r0, r0, #MCOUNT_INSN_SIZE
mcount_adjust_addr r0, lr @ instrumented function
adr lr, BSYM(2f)
mov pc, r2
2: mcount_exit
@ -184,8 +188,7 @@ ENDPROC(ret_from_fork)
mcount_enter
mcount_get_lr r1 @ lr of instrumented func
mov r0, lr @ instrumented function
sub r0, r0, #MCOUNT_INSN_SIZE
mcount_adjust_addr r0, lr @ instrumented function
.globl ftrace_call\suffix
ftrace_call\suffix:
@ -205,11 +208,11 @@ ftrace_graph_call\suffix:
#ifdef CONFIG_DYNAMIC_FTRACE
@ called from __ftrace_caller, saved in mcount_enter
ldr r1, [sp, #16] @ instrumented routine (func)
mcount_adjust_addr r1, r1
#else
@ called from __mcount, untouched in lr
mov r1, lr @ instrumented routine (func)
mcount_adjust_addr r1, lr @ instrumented routine (func)
#endif
sub r1, r1, #MCOUNT_INSN_SIZE
mov r2, fp @ frame pointer
bl prepare_ftrace_return
mcount_exit