5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Heiko Carstens hca@linux.ibm.com
[ Upstream commit e6b2dab41888332bf83f592131e7ea07756770a4 ]
The KERNEL_FPR mask only contains a flag for the first eight vector registers. However floating point registers overlay parts of the first sixteen vector registers.
This could lead to vector register corruption if a kernel fpu context uses any of the vector registers 8 to 15 and is interrupted or calls a KERNEL_FPR context. If that context uses also vector registers 8 to 15, their contents will be corrupted on return.
Luckily this is currently not a real bug, since the kernel has only one KERNEL_FPR user with s390_adjust_jiffies() and it is only using floating point registers 0 to 2.
Fix this by using the correct bits for KERNEL_FPR.
Fixes: 7f79695cc1b6 ("s390/fpu: improve kernel_fpu_[begin|end]") Signed-off-by: Heiko Carstens hca@linux.ibm.com Reviewed-by: Hendrik Brueckner brueckner@linux.ibm.com Signed-off-by: Alexander Gordeev agordeev@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/include/asm/fpu/api.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/s390/include/asm/fpu/api.h b/arch/s390/include/asm/fpu/api.h index 34a7ae68485c6..be16a6c0f1276 100644 --- a/arch/s390/include/asm/fpu/api.h +++ b/arch/s390/include/asm/fpu/api.h @@ -76,7 +76,7 @@ static inline int test_fp_ctl(u32 fpc) #define KERNEL_VXR_HIGH (KERNEL_VXR_V16V23|KERNEL_VXR_V24V31)
#define KERNEL_VXR (KERNEL_VXR_LOW|KERNEL_VXR_HIGH) -#define KERNEL_FPR (KERNEL_FPC|KERNEL_VXR_V0V7) +#define KERNEL_FPR (KERNEL_FPC|KERNEL_VXR_LOW)
struct kernel_fpu;