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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Nicolas Pitre <nico@linaro.org>,
	Russell King <rmk+kernel@armlinux.org.uk>,
	Nick Desaulniers <ndesaulniers@google.com>
Subject: [PATCH 4.14 8/8] ARM: 8702/1: head-common.S: Clear lr before jumping to start_kernel()
Date: Wed,  5 Aug 2020 17:53:34 +0200	[thread overview]
Message-ID: <20200805153507.382671788@linuxfoundation.org> (raw)
In-Reply-To: <20200805153507.005753845@linuxfoundation.org>

From: Geert Uytterhoeven <geert@linux-m68k.org>

commit 59b6359dd92d18f5dc04b14a4c926fa08ab66f7c upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>

---
 arch/arm/kernel/head-common.S |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -101,6 +101,7 @@ __mmap_switched:
 	str	r2, [r6]			@ Save atags pointer
 	cmp	r7, #0
 	strne	r0, [r7]			@ Save control register values
+	mov	lr, #0
 	b	start_kernel
 ENDPROC(__mmap_switched)
 



  parent reply	other threads:[~2020-08-05 20:06 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-05 15:53 [PATCH 4.14 0/8] 4.14.193-rc1 review Greg Kroah-Hartman
2020-08-05 15:53 ` [PATCH 4.14 1/8] Revert "scsi: libsas: direct call probe and destruct" Greg Kroah-Hartman
2020-08-05 15:53 ` [PATCH 4.14 2/8] random32: update the net random state on interrupt and activity Greg Kroah-Hartman
2020-08-05 15:53 ` [PATCH 4.14 3/8] ARM: percpu.h: fix build error Greg Kroah-Hartman
2020-08-05 15:53 ` [PATCH 4.14 4/8] random: fix circular include dependency on arm64 after addition of percpu.h Greg Kroah-Hartman
2020-08-05 15:53 ` [PATCH 4.14 5/8] random32: remove net_rand_state from the latent entropy gcc plugin Greg Kroah-Hartman
2020-08-05 15:53 ` [PATCH 4.14 6/8] random32: move the pseudo-random 32-bit definitions to prandom.h Greg Kroah-Hartman
2020-08-05 15:53 ` [PATCH 4.14 7/8] ext4: fix direct I/O read error Greg Kroah-Hartman
2020-08-05 15:53 ` Greg Kroah-Hartman [this message]
2020-08-05 19:48 ` [PATCH 4.14 0/8] 4.14.193-rc1 review Jon Hunter
2020-08-06 10:35 ` Naresh Kamboju
2020-08-06 18:57 ` Guenter Roeck
2020-08-06 19:34 ` Shuah Khan

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