On Wed Aug 24, 2022 at 12:05 PM AEST, Rohan McLure wrote: > 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.
Can I bikeshed this a bit more and ask if you would change the order? Saving and restoring macros are incidental, and are neither the change nor the reson for it. I think the changelog reads better if you state the change (or the problem) up front. Provid register zeroing macros ... follow the same convention as existing register stack save/restore macros ... will be used in later change to zero registers. Or not, if you disagree. Reviewed-by: Nicholas Piggin <npig...@gmail.com> > The resulting macros are called ZEROIZE_GPRS and ZEROIZE_NVGPRS, keeping > with the naming of the accompanying restore and save macros, and usage > of zeroize to describe this operation elsewhere in the kernel. > > Signed-off-by: Rohan McLure <rmcl...@linux.ibm.com> > --- > 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. > V3 -> V4: Update commit message to use zeroize. > --- > 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) > > -- > 2.34.1
