[PATCH 02/24] ARM: Fix FIQ code on VIVT CPUs

Kamal Mostafa kamal at canonical.com
Mon Sep 9 18:44:52 UTC 2013 -stable review patch.  If anyone has any objections, please let me know.


From: Russell King <rmk+kernel at arm.linux.org.uk>

commit 2ba85e7af4c639d933c9a87a6d7363f2983d5ada upstream.

Aaro Koskinen reports the following oops:
Installing fiq handler from c001b110, length 0x164
Unable to handle kernel paging request at virtual address ffff1224
pgd = c0004000
[ffff1224] *pgd=00000000, *pte=11fff0cb, *ppte=11fff00a
[<c0013154>] (set_fiq_handler+0x0/0x6c) from [<c0365d38>] (ams_delta_init_fiq+0xa8/0x160)
 r6:00000164 r5:c001b110 r4:00000000 r3:fefecb4c
[<c0365c90>] (ams_delta_init_fiq+0x0/0x160) from [<c0365b14>] (ams_delta_init+0xd4/0x114)
 r6:00000000 r5:fffece10 r4:c037a9e0
[<c0365a40>] (ams_delta_init+0x0/0x114) from [<c03613b4>] (customize_machine+0x24/0x30)

This is because the vectors page is now write-protected, and to change
code in there we must write to its original alias.  Make that change,
and adjust the cache flushing such that the code will become visible
to the instruction stream on VIVT CPUs.

Reported-by: Aaro Koskinen <aaro.koskinen at iki.fi>
Tested-by: Aaro Koskinen <aaro.koskinen at iki.fi>
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 arch/arm/kernel/fiq.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/arm/kernel/fiq.c b/arch/arm/kernel/fiq.c
index 25442f4..fc79202 100644
--- a/arch/arm/kernel/fiq.c
+++ b/arch/arm/kernel/fiq.c
@@ -84,17 +84,13 @@ int show_fiq_list(struct seq_file *p, int prec)
 void set_fiq_handler(void *start, unsigned int length)
-	void *base = (void *)0xffff0000;
 	void *base = vectors_page;
 	unsigned offset = FIQ_OFFSET;
 	memcpy(base + offset, start, length);
+	if (!cache_is_vipt_nonaliasing())
+		flush_icache_range(base + offset, offset + length);
 	flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length);
-	if (!vectors_high())
-		flush_icache_range(offset, offset + length);
 int claim_fiq(struct fiq_handler *f)

More information about the kernel-team mailing list