Re: [PATCH v3 11/18] powerpc: Add ZEROIZE_GPRS macros for register clears
From: Christophe Leroy <hidden>
Date: 2022-08-19 06:46:08
Le 19/08/2022 à 05:37, Rohan McLure a écrit :
Macros for restoring and saving registers to and from the stack exist. Provide macros with the same interface for clearing a range of gprs by setting each register's value in that range to zero. The resulting macros are called ZEROIZE_GPRS and ZEROIZE_NVGPRS, keeping with the naming of the accompanying restore and save macros, and usage of nullify to describe this operation elsewhere in the kernel.
s/nullify/zeroize
quoted hunk ↗ jump to hunk
Signed-off-by: Rohan McLure <redacted> --- V1 -> V2: Change 'ZERO' usage in naming to 'NULLIFY', a more obvious verb V2 -> V3: Change 'NULLIFY' usage in naming to 'ZEROIZE', which has precedent in kernel and explicitly specifies that we are zeroing. --- arch/powerpc/include/asm/ppc_asm.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h index 83c02f5a7f2a..b95689ada59c 100644 --- a/arch/powerpc/include/asm/ppc_asm.h +++ b/arch/powerpc/include/asm/ppc_asm.h@@ -33,6 +33,20 @@ .endr .endm +/* + * This expands to a sequence of register clears for regs start to end + * inclusive, of the form: + * + * li rN, 0 + */ +.macro ZEROIZE_REGS start, end + .Lreg=\start + .rept (\end - \start + 1) + li .Lreg, 0 + .Lreg=.Lreg+1 + .endr +.endm + /* * Macros for storing registers into and loading registers from * exception frames.@@ -49,6 +63,14 @@ #define REST_NVGPRS(base) REST_GPRS(13, 31, base) #endif +#define ZEROIZE_GPRS(start, end) ZEROIZE_REGS start, end +#ifdef __powerpc64__ +#define ZEROIZE_NVGPRS() ZEROIZE_GPRS(14, 31) +#else +#define ZEROIZE_NVGPRS() ZEROIZE_GPRS(13, 31) +#endif +#define ZEROIZE_GPR(n) ZEROIZE_GPRS(n, n) + #define SAVE_GPR(n, base) SAVE_GPRS(n, n, base) #define REST_GPR(n, base) REST_GPRS(n, n, base)