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s390/fpu: make use of __uninitialized macro

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Code sections in s390 specific kernel code which use floating point or
vector registers all come with a 520 byte stack variable to save already in
use registers, if required.

With INIT_STACK_ALL_PATTERN or INIT_STACK_ALL_ZERO enabled this variable
will always be initialized on function entry in addition to saving register
contents, which contradicts the intention (performance improvement) of such
code sections.

Therefore provide a DECLARE_KERNEL_FPU_ONSTACK() macro which provides
struct kernel_fpu variables with an __uninitialized attribute, and convert
all existing code to use this.

This way only this specific type of stack variable will not be initialized,
regardless of config options.

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20240205154844.3757121-3-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Heiko Carstens
2024-02-05 16:48:44 +01:00
parent fd7eea27a3
commit 8d16ce1488
5 changed files with 8 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
arch/s390/crypto/chacha-glue.c
View File

@@ -22,7 +22,7 @@ static void chacha20_crypt_s390(u32 *state, u8 *dst, const u8 *src,
unsigned int nbytes, const u32 *key,
u32 *counter)
{
struct kernel_fpu vxstate;
DECLARE_KERNEL_FPU_ONSTACK(vxstate);
kernel_fpu_begin(&vxstate, KERNEL_VXR);
chacha20_vx(dst, src, nbytes, key, counter);

2
arch/s390/crypto/crc32-vx.c
View File

@@ -49,8 +49,8 @@ u32 crc32c_le_vgfm_16(u32 crc, unsigned char const *buf, size_t size);
static u32 __pure ___fname(u32 crc, \
unsigned char const *data, size_t datalen) \
{ \
struct kernel_fpu vxstate; \
unsigned long prealign, aligned, remaining; \
DECLARE_KERNEL_FPU_ONSTACK(vxstate); \
\
if (datalen < VX_MIN_LEN + VX_ALIGN_MASK) \
return ___crc32_sw(crc, data, datalen); \

3
arch/s390/include/asm/fpu/types.h
View File

@@ -35,4 +35,7 @@ struct kernel_fpu {
};
};
#define DECLARE_KERNEL_FPU_ONSTACK(name) \
struct kernel_fpu name __uninitialized
#endif /* _ASM_S390_FPU_TYPES_H */

2
arch/s390/kernel/sysinfo.c
View File

@@ -426,9 +426,9 @@ subsys_initcall(create_proc_service_level);
*/
void s390_adjust_jiffies(void)
{
DECLARE_KERNEL_FPU_ONSTACK(fpu);
struct sysinfo_1_2_2 *info;
unsigned long capability;
struct kernel_fpu fpu;
info = (void *) get_zeroed_page(GFP_KERNEL);
if (!info)

4
lib/raid6/s390vx.uc
View File

@@ -81,7 +81,7 @@ static inline void COPY_VEC(int x, int y)
static void raid6_s390vx$#_gen_syndrome(int disks, size_t bytes, void **ptrs)
{
struct kernel_fpu vxstate;
DECLARE_KERNEL_FPU_ONSTACK(vxstate);
u8 **dptr, *p, *q;
int d, z, z0;
@@ -114,7 +114,7 @@ static void raid6_s390vx$#_gen_syndrome(int disks, size_t bytes, void **ptrs)
static void raid6_s390vx$#_xor_syndrome(int disks, int start, int stop,
size_t bytes, void **ptrs)
{
struct kernel_fpu vxstate;
DECLARE_KERNEL_FPU_ONSTACK(vxstate);
u8 **dptr, *p, *q;
int d, z, z0;