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SubjectRe: [PATCH 03/11] x86/fpu: make __raw_xsave_addr() use feature number instead of mask
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Sebastian Andrzej Siewior writes:

> Most users of __raw_xsave_addr() use a feature number, shift it to a
> mask and then __raw_xsave_addr() shifts it back to the feature number.
>
> Make __raw_xsave_addr() use the feature number as argument.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
> arch/x86/kernel/fpu/xstate.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
> index 87a57b7642d36..38d0b5ea40425 100644
> --- a/arch/x86/kernel/fpu/xstate.c
> +++ b/arch/x86/kernel/fpu/xstate.c
> @@ -811,10 +811,8 @@ void fpu__resume_cpu(void)
> *
> * Note: does not work for compacted buffers.
> */
> -void *__raw_xsave_addr(struct xregs_state *xsave, int xstate_feature_mask)
> +void *__raw_xsave_addr(struct xregs_state *xsave, int feature_nr)

It might be clearer to offer both interfaces, since both are used?

> {
> - int feature_nr = fls64(xstate_feature_mask) - 1;
> -
> if (!xfeature_enabled(feature_nr)) {
> WARN_ON_FPU(1);
> return NULL;
> @@ -842,6 +840,7 @@ void *__raw_xsave_addr(struct xregs_state *xsave, int xstate_feature_mask)
> */
> void *get_xsave_addr(struct xregs_state *xsave, int xstate_feature)
> {
> + int feature_nr;
> /*
> * Do we even *have* xsave state?
> */
> @@ -869,7 +868,8 @@ void *get_xsave_addr(struct xregs_state *xsave, int xstate_feature)
> if (!(xsave->header.xfeatures & xstate_feature))
> return NULL;
>
> - return __raw_xsave_addr(xsave, xstate_feature);
> + feature_nr = fls64(xstate_feature) - 1;
> + return __raw_xsave_addr(xsave, feature_nr);

and then move that to a wrapper function that takes a mask?

> }
> EXPORT_SYMBOL_GPL(get_xsave_addr);
>
> @@ -1018,7 +1018,7 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int of
> * Copy only in-use xstates:
> */
> if ((header.xfeatures >> i) & 1) {
> - void *src = __raw_xsave_addr(xsave, 1 << i);
> + void *src = __raw_xsave_addr(xsave, i);
>
> offset = xstate_offsets[i];
> size = xstate_sizes[i];
> @@ -1104,7 +1104,7 @@ int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned i
> * Copy only in-use xstates:
> */
> if ((header.xfeatures >> i) & 1) {
> - void *src = __raw_xsave_addr(xsave, 1 << i);
> + void *src = __raw_xsave_addr(xsave, i);
>
> offset = xstate_offsets[i];
> size = xstate_sizes[i];
> @@ -1161,7 +1161,7 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
> u64 mask = ((u64)1 << i);
>
> if (hdr.xfeatures & mask) {
> - void *dst = __raw_xsave_addr(xsave, 1 << i);
> + void *dst = __raw_xsave_addr(xsave, i);
>
> offset = xstate_offsets[i];
> size = xstate_sizes[i];
> @@ -1215,7 +1215,7 @@ int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
> u64 mask = ((u64)1 << i);
>
> if (hdr.xfeatures & mask) {
> - void *dst = __raw_xsave_addr(xsave, 1 << i);
> + void *dst = __raw_xsave_addr(xsave, i);
>
> offset = xstate_offsets[i];
> size = xstate_sizes[i];


--
Cheers,
Christophe de Dinechin (IRC c3d)

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