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authorRussell King <rmk+kernel@arm.linux.org.uk>2013-02-25 16:09:12 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-03-14 11:32:03 -0700
commit95a2b9b9ce9db0856f0603f394a628e1360f79ae (patch)
tree7842ebbbf7962d5eb292e24da7e105a4606f070e /arch
parente28c3f2b514b5581e15614f7cf976131092cf4b6 (diff)
ARM: VFP: fix emulation of second VFP instruction
commit 5e4ba617c1b584b2e376f31a63bd4e734109318a upstream. Martin Storsjö reports that the sequence: ee312ac1 vsub.f32 s4, s3, s2 ee702ac0 vsub.f32 s5, s1, s0 e59f0028 ldr r0, [pc, #40] ee111a90 vmov r1, s3 on Raspberry Pi (implementor 41 architecture 1 part 20 variant b rev 5) where s3 is a denormal and s2 is zero results in incorrect behaviour - the instruction "vsub.f32 s5, s1, s0" is not executed: VFP: bounce: trigger ee111a90 fpexc d0000780 VFP: emulate: INST=0xee312ac1 SCR=0x00000000 ... As we can see, the instruction triggering the exception is the "vmov" instruction, and we emulate the "vsub.f32 s4, s3, s2" but fail to properly take account of the FPEXC_FP2V flag in FPEXC. This is because the test for the second instruction register being valid is bogus, and will always skip emulation of the second instruction. Reported-by: Martin Storsjö <martin@martin.st> Tested-by: Martin Storsjö <martin@martin.st> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/vfp/vfpmodule.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index ce1880286961..e9c8f532e8ae 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -369,7 +369,7 @@ void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
* If there isn't a second FP instruction, exit now. Note that
* the FPEXC.FP2V bit is valid only if FPEXC.EX is 1.
*/
- if (fpexc ^ (FPEXC_EX | FPEXC_FP2V))
+ if ((fpexc & (FPEXC_EX | FPEXC_FP2V)) != (FPEXC_EX | FPEXC_FP2V))
goto exit;
/*