Include in asm/ppc_asm.h macros to be used in multiple successive patches to implement zeroising architected registers in interrupt handlers. Registers will be sanitised in this fashion in future patches to reduce the speculation influence of user-controlled register values. These mitigations will be configurable through the CONFIG_INTERRUPT_SANITIZE_REGISTERS Kconfig option.
Included are macros for conditionally zeroising registers and restoring as required with the mitigation enabled. With the mitigation disabled, non-volatiles must be restored on demand at separate locations to those required by the mitigation. Reviewed-by: Nicholas Piggin <npig...@gmail.com> Signed-off-by: Rohan McLure <rmcl...@linux.ibm.com> --- v4: New patch v5: Remove unnecessary _ZEROIZE_ parts of macro titles, as the implementation of how registers are sanitised doesn't need to be immediately accessible, only that values will be clobbered. Introduce arbitrary sanitize gpr(s) macros. --- arch/powerpc/include/asm/ppc_asm.h | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h index 753a2757bcd4..d2f44612f4b0 100644 --- a/arch/powerpc/include/asm/ppc_asm.h +++ b/arch/powerpc/include/asm/ppc_asm.h @@ -74,6 +74,25 @@ #define SAVE_GPR(n, base) SAVE_GPRS(n, n, base) #define REST_GPR(n, base) REST_GPRS(n, n, base) +/* macros for handling user register sanitisation */ +#ifdef CONFIG_INTERRUPT_SANITIZE_REGISTERS +#define SANITIZE_SYSCALL_GPRS() ZEROIZE_GPR(0); \ + ZEROIZE_GPRS(5, 12); \ + ZEROIZE_NVGPRS() +#define SANITIZE_GPR(n) ZEROIZE_GPR(n) +#define SANITIZE_GPRS(start, end) ZEROIZE_GPRS(start, end) +#define SANITIZE_NVGPRS() ZEROIZE_NVGPRS() +#define SANITIZE_RESTORE_NVGPRS() REST_NVGPRS(r1) +#define HANDLER_RESTORE_NVGPRS() +#else +#define SANITIZE_SYSCALL_GPRS() +#define SANITIZE_GPR(n) +#define SANITIZE_GPRS(start, end) +#define SANITIZE_NVGPRS() +#define SANITIZE_RESTORE_NVGPRS() +#define HANDLER_RESTORE_NVGPRS() REST_NVGPRS(r1) +#endif /* CONFIG_INTERRUPT_SANITIZE_REGISTERS */ + #define SAVE_FPR(n, base) stfd n,8*TS_FPRWIDTH*(n)(base) #define SAVE_2FPRS(n, base) SAVE_FPR(n, base); SAVE_FPR(n+1, base) #define SAVE_4FPRS(n, base) SAVE_2FPRS(n, base); SAVE_2FPRS(n+2, base) -- 2.37.2