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authorRabin Vincent <rabin@rab.in>2010-08-10 19:37:21 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-09-02 15:26:12 +0100
commita3ba87a614992500cf2c47e6f788e74a971ce91f (patch)
tree5b644570cf2d93e6216a0c308e1fbf72efda2913 /arch/arm/kernel/entry-common.S
parent72fa62fa5dff0e2e06491dd99c429adb137f299b (diff)
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ARM: 6316/1: ftrace: add Thumb-2 support
Fix the mcount routines to build and run on a kernel built with the Thumb-2 instruction set by correcting the following errors using the fixes suggested by Catalin Marinas: - Problem: The following assembler errors appear at the "adr r0, ftrace_stub" instruction: entry-common.S: Assembler messages: entry-common.S:179: Error: invalid immediate for address calculation (value = 0x00000004) Fix: The errors don't occur with a non-global symbol, so use one. - Problem: The "mov lr, pc" does not set the lsb when storing the pc in lr. The called function returns with "bx lr", and the mode changes to ARM. Fix: Add a label on the return address and use "adr lr, BSYM(label)". We don't modify the old mcount because it won't be built when using Thumb-2. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/entry-common.S')
-rw-r--r--arch/arm/kernel/entry-common.S6
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index c7a8c208a45c..f5e75de0203e 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -167,7 +167,7 @@ ENTRY(__gnu_mcount_nc)
stmdb sp!, {r0-r3, lr}
ldr r0, =ftrace_trace_function
ldr r2, [r0]
- adr r0, ftrace_stub
+ adr r0, .Lftrace_stub
cmp r0, r2
bne gnu_trace
ldmia sp!, {r0-r3, ip, lr}
@@ -177,8 +177,9 @@ gnu_trace:
ldr r1, [sp, #20] @ lr of instrumented routine
mov r0, lr
sub r0, r0, #MCOUNT_INSN_SIZE
- mov lr, pc
+ adr lr, BSYM(1f)
mov pc, r2
+1:
ldmia sp!, {r0-r3, ip, lr}
mov pc, ip
ENDPROC(__gnu_mcount_nc)
@@ -213,6 +214,7 @@ ENDPROC(mcount)
#endif /* CONFIG_DYNAMIC_FTRACE */
ENTRY(ftrace_stub)
+.Lftrace_stub:
mov pc, lr
ENDPROC(ftrace_stub)