unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
1
Fork 0
Code Pull requests 5 Wiki Activity

ARM: 7030/1: entry: Remove unnecessary masking when decoding Thumb-2 instructions

Browse source 
When testing whether a Thumb-2 instruction is 32 bits long or not,
the masking done in order to test bits 11-15 of the first
instruction halfword won't affect the result of the comparison, so
remove it.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Reviewed-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Dave Martin 2011-08-19 17:59:27 +01:00 committed by Russell King
parent 2ecccf90f2
commit 85519189df
1 changed files with 2 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
arch/arm/kernel/entry-armv.S
View file

@ -262,8 +262,7 @@ __und_svc:
ldr r0, [r4, #-4]
#else
ldrh r0, [r4, #-2] @ Thumb instruction at LR - 2
and r9, r0, #0xf800
cmp r9, #0xe800 @ 32-bit instruction if xx >= 0
cmp r0, #0xe800 @ 32-bit instruction if xx >= 0
ldrhhs r9, [r4] @ bottom 16 bits
orrhs r0, r9, r0, lsl #16
#endif
@ -445,8 +444,7 @@ __und_usr:
ARM( ldrht r5, [r4], #2 )
THUMB( ldrht r5, [r4] )
THUMB( add r4, r4, #2 )
and r0, r5, #0xf800 @ mask bits 111x x... .... ....
cmp r0, #0xe800 @ 32bit instruction if xx != 0
cmp r5, #0xe800 @ 32bit instruction if xx != 0
blo __und_usr_unknown
3: ldrht r0, [r4]
add r2, r2, #2 @ r2 is PC + 2, make it PC + 4