Implement nospec_load() and nospec_ptr() for s390 with the new gmb() barrier between the boundary condition and the load that may not be done speculatively.
Acked-by: Christian Borntraeger <[email protected]> Signed-off-by: Martin Schwidefsky <[email protected]> --- arch/s390/include/asm/barrier.h | 38 ++++++++++++++++++++++++++++++++++++++ arch/s390/kernel/alternative.c | 7 +++++++ 2 files changed, 45 insertions(+) diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h index 1043260..b8836a6 100644 --- a/arch/s390/include/asm/barrier.h +++ b/arch/s390/include/asm/barrier.h @@ -8,6 +8,8 @@ #ifndef __ASM_BARRIER_H #define __ASM_BARRIER_H +#include <asm/alternative.h> + /* * Force strict CPU ordering. * And yes, this is required on UP too when we're talking @@ -23,6 +25,42 @@ #define mb() do { asm volatile(__ASM_BARRIER : : : "memory"); } while (0) +static inline void gmb(void) +{ + asm volatile( + ALTERNATIVE("", ".long 0xb2e8f000", 81) + : : : "memory"); +} +#define gmb gmb + +#define nospec_ptr(ptr, lo, hi) \ +({ \ + typeof (ptr) __ptr = (ptr); \ + typeof (ptr) __lo = (lo); \ + typeof (ptr) __hi = (hi); \ + typeof (ptr) __vptr = NULL; \ + \ + if (__lo <= __ptr && __ptr < __hi) { \ + gmb(); \ + __vptr = __ptr; \ + } \ + __vptr; \ +}) + +#define nospec_load(ptr, lo, hi) \ +({ \ + typeof (ptr) __ptr = (ptr); \ + typeof (ptr) __lo = (lo); \ + typeof (ptr) __hi = (hi); \ + typeof (*ptr) __v = (typeof(*__ptr))(unsigned long) 0; \ + \ + if (__lo <= __ptr && __ptr < __hi) { \ + gmb(); \ + __v = *__ptr; \ + } \ + __v; \ +}) + #define rmb() barrier() #define wmb() barrier() #define dma_rmb() mb() diff --git a/arch/s390/kernel/alternative.c b/arch/s390/kernel/alternative.c index 1abf4f3..33d2e88 100644 --- a/arch/s390/kernel/alternative.c +++ b/arch/s390/kernel/alternative.c @@ -15,6 +15,13 @@ static int __init disable_alternative_instructions(char *str) early_param("noaltinstr", disable_alternative_instructions); +static int __init nogmb_setup_early(char *str) +{ + __clear_facility(81, S390_lowcore.alt_stfle_fac_list); + return 0; +} +early_param("nogmb", nogmb_setup_early); + struct brcl_insn { u16 opc; s32 disp; -- 2.7.4
