__und_usr_thumb function deals with thumb2 opcodes. In case of BE image, it needs to byteswap half word thumb2 encoded instructions before further processing them.
Without this fix BE image user-land thread executing first VFP instruction encoded in thumb2 fails with SIGILL, because kernel does not recognize instruction and does not enable VFP.
Reported-by: Corey Melton comelton@cisco.com Signed-off-by: Victor Kamensky victor.kamensky@linaro.org --- arch/arm/kernel/entry-armv.S | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index b3fb8c9..1879e8d 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -451,9 +451,11 @@ __und_usr_thumb: .arch armv6t2 #endif 2: ldrht r5, [r4] +ARM_BE8(rev16 r5, r5) @ little endian instruction cmp r5, #0xe800 @ 32bit instruction if xx != 0 blo __und_usr_fault_16 @ 16bit undefined instruction 3: ldrht r0, [r2] +ARM_BE8(rev16 r0, r0) @ little endian instruction add r2, r2, #2 @ r2 is PC + 2, make it PC + 4 str r2, [sp, #S_PC] @ it's a 2x16bit instr, update orr r0, r0, r5, lsl #16
On Mon, Jan 13, 2014 at 02:30:51PM -0800, Victor Kamensky wrote:
__und_usr_thumb function deals with thumb2 opcodes. In case of BE image, it needs to byteswap half word thumb2 encoded instructions before further processing them.
Without this fix BE image user-land thread executing first VFP instruction encoded in thumb2 fails with SIGILL, because kernel does not recognize instruction and does not enable VFP.
Reported-by: Corey Melton comelton@cisco.com Signed-off-by: Victor Kamensky victor.kamensky@linaro.org
Good spot. This looks like the correct fix to me.
Acked-by: Dave Martin Dave.Martin@arm.com
arch/arm/kernel/entry-armv.S | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index b3fb8c9..1879e8d 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -451,9 +451,11 @@ __und_usr_thumb: .arch armv6t2 #endif 2: ldrht r5, [r4] +ARM_BE8(rev16 r5, r5) @ little endian instruction cmp r5, #0xe800 @ 32bit instruction if xx != 0 blo __und_usr_fault_16 @ 16bit undefined instruction 3: ldrht r0, [r2] +ARM_BE8(rev16 r0, r0) @ little endian instruction add r2, r2, #2 @ r2 is PC + 2, make it PC + 4 str r2, [sp, #S_PC] @ it's a 2x16bit instr, update orr r0, r0, r5, lsl #16 -- 1.8.1.4
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On 01/14/14 01:05, Dave Martin wrote:
On Mon, Jan 13, 2014 at 02:30:51PM -0800, Victor Kamensky wrote:
__und_usr_thumb function deals with thumb2 opcodes. In case of BE image, it needs to byteswap half word thumb2 encoded instructions before further processing them.
Without this fix BE image user-land thread executing first VFP instruction encoded in thumb2 fails with SIGILL, because kernel does not recognize instruction and does not enable VFP.
Reported-by: Corey Melton comelton@cisco.com Signed-off-by: Victor Kamensky victor.kamensky@linaro.org
Good spot. This looks like the correct fix to me.
Acked-by: Dave Martin Dave.Martin@arm.com
Can you please send this to the patch tracker? Feel free to add
Tested-by: Stephen Boyd sboyd@codeaurora.org
On 20 January 2014 17:56, Stephen Boyd sboyd@codeaurora.org wrote:
On 01/14/14 01:05, Dave Martin wrote:
On Mon, Jan 13, 2014 at 02:30:51PM -0800, Victor Kamensky wrote:
__und_usr_thumb function deals with thumb2 opcodes. In case of BE image, it needs to byteswap half word thumb2 encoded instructions before further processing them.
Without this fix BE image user-land thread executing first VFP instruction encoded in thumb2 fails with SIGILL, because kernel does not recognize instruction and does not enable VFP.
Reported-by: Corey Melton comelton@cisco.com Signed-off-by: Victor Kamensky victor.kamensky@linaro.org
Good spot. This looks like the correct fix to me.
Acked-by: Dave Martin Dave.Martin@arm.com
Can you please send this to the patch tracker? Feel free to add
Tested-by: Stephen Boyd sboyd@codeaurora.org
Thanks. It is done on both counts. Patch is submitted as [1].
Thanks, Victor
[1] http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=7946/1
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