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ARM: 8702/1: head-common.S: Clear lr before jumping to start_kernel()

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If CONFIG_DEBUG_LOCK_ALLOC=y, the kernel log is spammed with a few
hundred identical messages:

    unwind: Unknown symbol address c0800300
    unwind: Index not found c0800300

c0800300 is the return address from the last subroutine call (to
__memzero()) in __mmap_switched().  Apparently having this address in
the link register confuses the unwinder.

To fix this, reset the link register to zero before jumping to
start_kernel().

Fixes: 9520b1a1b5f7a348 ("ARM: head-common.S: speed up startup code")
Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Geert Uytterhoeven 2017-10-03 19:14:38 +01:00 committed by Russell King
parent 1bb078330b
commit 59b6359dd9
1 changed files with 1 additions and 0 deletions
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arch/arm/kernel/head-common.S
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@ -114,6 +114,7 @@ __mmap_switched:
str r8, [r2] @ Save atags pointer str r8, [r2] @ Save atags pointer
cmp r3, #0 cmp r3, #0
strne r10, [r3] @ Save control register values strne r10, [r3] @ Save control register values
mov lr, #0
b start_kernel b start_kernel
ENDPROC(__mmap_switched) ENDPROC(__mmap_switched)