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ARM: 9169/1: entry: fix Thumb2 bug in iWMMXt exception handling
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The Thumb2 version of the FP exception handling entry code treats the
register holding the CP number (R8) differently, resulting in the iWMMXT
CP number check to be incorrect.

Fix this by unifying the ARM and Thumb2 code paths, and switch the
order of the additions of the TI_USED_CP offset and the shifted CP
index.

Cc: <stable@vger.kernel.org>
Fixes: b86040a ("Thumb-2: Implementation of the unified start-up and exceptions code")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
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ardbiesheuvel authored and Russell King (Oracle) committed Dec 17, 2021
1 parent 7202216 commit 8536a5e
Showing 1 changed file with 3 additions and 5 deletions.
8 changes: 3 additions & 5 deletions arch/arm/kernel/entry-armv.S
Original file line number Diff line number Diff line change
Expand Up @@ -596,11 +596,9 @@ call_fpe:
tstne r0, #0x04000000 @ bit 26 set on both ARM and Thumb-2
reteq lr
and r8, r0, #0x00000f00 @ mask out CP number
THUMB( lsr r8, r8, #8 )
mov r7, #1
add r6, r10, #TI_USED_CP
ARM( strb r7, [r6, r8, lsr #8] ) @ set appropriate used_cp[]
THUMB( strb r7, [r6, r8] ) @ set appropriate used_cp[]
add r6, r10, r8, lsr #8 @ add used_cp[] array offset first
strb r7, [r6, #TI_USED_CP] @ set appropriate used_cp[]
#ifdef CONFIG_IWMMXT
@ Test if we need to give access to iWMMXt coprocessors
ldr r5, [r10, #TI_FLAGS]
Expand All @@ -609,7 +607,7 @@ call_fpe:
bcs iwmmxt_task_enable
#endif
ARM( add pc, pc, r8, lsr #6 )
THUMB( lsl r8, r8, #2 )
THUMB( lsr r8, r8, #6 )
THUMB( add pc, r8 )
nop

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