[PATCH 3.10 28/35] ARM: Fix FIQ code on VIVT CPUs

From: Greg Kroah-Hartman
Date: Fri Aug 14 2015 - 14:11:46 EST

3.10-stable review patch. If anyone has any objections, please let me know.


From: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>

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@xxxxxx>
Tested-by: Aaro Koskinen <aaro.koskinen@xxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Cc: Martin Kaiser <lists@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/arm/kernel/fiq.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

--- a/arch/arm/kernel/fiq.c
+++ b/arch/arm/kernel/fiq.c
@@ -84,17 +84,13 @@ int show_fiq_list(struct seq_file *p, in

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)

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