| Message ID | 20181004140547.13014-4-bigeasy@linutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86: load FPU registers on return to userland | expand |
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)
On 10/04/2018 07:05 AM, Sebastian Andrzej Siewior wrote: > 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. This generally looks like a nice cleanup. Thanks for taking a look at it! > 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) > { Could we call this 'xfeature_nr' consistently? > - 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); > } Should we also be using a feature number for get_xsave_addr()? In other words, could you take a look and see how widely we should be doing this kind of conversion and not just limit it to __raw_xsave_addr()?
On Thu, Oct 04, 2018 at 04:05:39PM +0200, Sebastian Andrzej Siewior wrote: > 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) Don't forget to update the comment above it too - it still says "mask". Otherwise nice.
On 2018-10-12 08:52:03 [-0700], Dave Hansen wrote: > > 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) > > { > > Could we call this 'xfeature_nr' consistently? yes. > Should we also be using a feature number for get_xsave_addr()? In other > words, could you take a look and see how widely we should be doing this > kind of conversion and not just limit it to __raw_xsave_addr()? this brings us to: Subject: [PATCH] x86/fpu: Make get_xsave_field_ptr() and get_xsave_addr() use feature number instead of mask After changing the argument of __raw_xsave_addr() from a mask to number Dave suggested to check if it makes sense to do the same for get_xsave_addr(). As it turns out it does. Only get_xsave_addr() needs the mask to check if the requested feature is part of what is support/saved and then uses the number again. The shift operation is cheaper compared to "find last bit set". Also, the feature number uses less opcode space compared to the mask :) Make get_xsave_addr() argument a xfeature number instead of mask and fix up its callers. As part of this use xfeature_nr and xfeature_mask consistently. This results in changes to the kvm code as: feature -> xfeature_mask index -> xfeature_nr Suggested-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- arch/x86/include/asm/fpu/xstate.h | 2 +- arch/x86/kernel/fpu/xstate.c | 23 +++++++++++------------ arch/x86/kernel/traps.c | 2 +- arch/x86/kvm/x86.c | 28 ++++++++++++++-------------- arch/x86/mm/mpx.c | 6 +++--- 5 files changed, 30 insertions(+), 31 deletions(-) diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index 48581988d78c7..a0b6062012ed7 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -47,7 +47,7 @@ extern void __init update_regset_xstate_info(unsigned int size, void fpu__xstate_clear_all_cpu_caps(void); void *get_xsave_addr(struct xregs_state *xsave, int xstate); -const void *get_xsave_field_ptr(int xstate_field); +const void *get_xsave_field_ptr(int xfeature_nr); int using_compacted_format(void); int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset, unsigned int size); int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset, unsigned int size); diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 3dfe3627deaf6..375226055a413 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -832,15 +832,15 @@ static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr) * * Inputs: * xstate: the thread's storage area for all FPU data - * xstate_feature: state which is defined in xsave.h (e.g. - * XFEATURE_MASK_FP, XFEATURE_MASK_SSE, etc...) + * xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP, + * XFEATURE_SSE, etc...) * Output: * address of the state in the xsave area, or NULL if the * field is not present in the xsave buffer. */ -void *get_xsave_addr(struct xregs_state *xsave, int xstate_feature) +void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr) { - int xfeature_nr; + u64 xfeature_mask = 1ULL << xfeature_nr; /* * Do we even *have* xsave state? */ @@ -852,11 +852,11 @@ void *get_xsave_addr(struct xregs_state *xsave, int xstate_feature) * have not enabled. Remember that pcntxt_mask is * what we write to the XCR0 register. */ - WARN_ONCE(!(xfeatures_mask & xstate_feature), + WARN_ONCE(!(xfeatures_mask & xfeature_mask), "get of unsupported state"); /* * This assumes the last 'xsave*' instruction to - * have requested that 'xstate_feature' be saved. + * have requested that 'xfeature_mask' be saved. * If it did not, we might be seeing and old value * of the field in the buffer. * @@ -865,10 +865,9 @@ void *get_xsave_addr(struct xregs_state *xsave, int xstate_feature) * or because the "init optimization" caused it * to not be saved. */ - if (!(xsave->header.xfeatures & xstate_feature)) + if (!(xsave->header.xfeatures & xfeature_mask)) return NULL; - xfeature_nr = fls64(xstate_feature) - 1; return __raw_xsave_addr(xsave, xfeature_nr); } EXPORT_SYMBOL_GPL(get_xsave_addr); @@ -884,13 +883,13 @@ EXPORT_SYMBOL_GPL(get_xsave_addr); * Note that this only works on the current task. * * Inputs: - * @xsave_state: state which is defined in xsave.h (e.g. XFEATURE_MASK_FP, - * XFEATURE_MASK_SSE, etc...) + * @xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP, + * XFEATURE_SSE, etc...) * Output: * address of the state in the xsave area or NULL if the state * is not present or is in its 'init state'. */ -const void *get_xsave_field_ptr(int xsave_state) +const void *get_xsave_field_ptr(int xfeature_nr) { struct fpu *fpu = ¤t->thread.fpu; @@ -900,7 +899,7 @@ const void *get_xsave_field_ptr(int xsave_state) */ fpu__save(fpu); - return get_xsave_addr(&fpu->state.xsave, xsave_state); + return get_xsave_addr(&fpu->state.xsave, xfeature_nr); } #ifdef CONFIG_ARCH_HAS_PKEYS diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index e6db475164ede..aa4703d12e084 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -477,7 +477,7 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code) * which is all zeros which indicates MPX was not * responsible for the exception. */ - bndcsr = get_xsave_field_ptr(XFEATURE_MASK_BNDCSR); + bndcsr = get_xsave_field_ptr(XFEATURE_BNDCSR); if (!bndcsr) goto exit_trap; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ca717737347e6..78006ea3cf46f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3533,15 +3533,15 @@ static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu) */ valid = xstate_bv & ~XFEATURE_MASK_FPSSE; while (valid) { - u64 feature = valid & -valid; - int index = fls64(feature) - 1; - void *src = get_xsave_addr(xsave, feature); + u64 xfeature_mask = valid & -valid; + int xfeature_nr = fls64(xfeature_mask) - 1; + void *src = get_xsave_addr(xsave, xfeature_nr); if (src) { u32 size, offset, ecx, edx; - cpuid_count(XSTATE_CPUID, index, + cpuid_count(XSTATE_CPUID, xfeature_nr, &size, &offset, &ecx, &edx); - if (feature == XFEATURE_MASK_PKRU) + if (xfeature_nr == XFEATURE_PKRU) memcpy(dest + offset, &vcpu->arch.pkru, sizeof(vcpu->arch.pkru)); else @@ -3549,7 +3549,7 @@ static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu) } - valid -= feature; + valid -= xfeature_mask; } } @@ -3576,22 +3576,22 @@ static void load_xsave(struct kvm_vcpu *vcpu, u8 *src) */ valid = xstate_bv & ~XFEATURE_MASK_FPSSE; while (valid) { - u64 feature = valid & -valid; - int index = fls64(feature) - 1; - void *dest = get_xsave_addr(xsave, feature); + u64 xfeature_mask = valid & -valid; + int xfeature_nr = fls64(xfeature_mask) - 1; + void *dest = get_xsave_addr(xsave, xfeature_nr); if (dest) { u32 size, offset, ecx, edx; - cpuid_count(XSTATE_CPUID, index, + cpuid_count(XSTATE_CPUID, xfeature_nr, &size, &offset, &ecx, &edx); - if (feature == XFEATURE_MASK_PKRU) + if (xfeature_nr == XFEATURE_PKRU) memcpy(&vcpu->arch.pkru, src + offset, sizeof(vcpu->arch.pkru)); else memcpy(dest, src + offset, size); } - valid -= feature; + valid -= xfeature_mask; } } @@ -8562,11 +8562,11 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) if (init_event) kvm_put_guest_fpu(vcpu); mpx_state_buffer = get_xsave_addr(&vcpu->arch.guest_fpu.state.xsave, - XFEATURE_MASK_BNDREGS); + XFEATURE_BNDREGS); if (mpx_state_buffer) memset(mpx_state_buffer, 0, sizeof(struct mpx_bndreg_state)); mpx_state_buffer = get_xsave_addr(&vcpu->arch.guest_fpu.state.xsave, - XFEATURE_MASK_BNDCSR); + XFEATURE_BNDCSR); if (mpx_state_buffer) memset(mpx_state_buffer, 0, sizeof(struct mpx_bndcsr)); if (init_event) diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index e500949bae245..a50c3fe11c6ff 100644 --- a/arch/x86/mm/mpx.c +++ b/arch/x86/mm/mpx.c @@ -145,7 +145,7 @@ siginfo_t *mpx_generate_siginfo(struct pt_regs *regs) goto err_out; } /* get bndregs field from current task's xsave area */ - bndregs = get_xsave_field_ptr(XFEATURE_MASK_BNDREGS); + bndregs = get_xsave_field_ptr(XFEATURE_BNDREGS); if (!bndregs) { err = -EINVAL; goto err_out; @@ -202,7 +202,7 @@ static __user void *mpx_get_bounds_dir(void) * The bounds directory pointer is stored in a register * only accessible if we first do an xsave. */ - bndcsr = get_xsave_field_ptr(XFEATURE_MASK_BNDCSR); + bndcsr = get_xsave_field_ptr(XFEATURE_BNDCSR); if (!bndcsr) return MPX_INVALID_BOUNDS_DIR; @@ -388,7 +388,7 @@ static int do_mpx_bt_fault(void) const struct mpx_bndcsr *bndcsr; struct mm_struct *mm = current->mm; - bndcsr = get_xsave_field_ptr(XFEATURE_MASK_BNDCSR); + bndcsr = get_xsave_field_ptr(XFEATURE_BNDCSR); if (!bndcsr) return -EINVAL; /*
On 2018-10-11 19:30:07 [+0200], Christophe de Dinechin wrote: > > 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? > … > > @@ -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? made another patch this fls is gone now and everyone is using a number instead of a mask. Sebastian
On 2018-10-18 13:17:19 [+0200], To Dave Hansen wrote: > --- a/arch/x86/include/asm/fpu/xstate.h > +++ b/arch/x86/include/asm/fpu/xstate.h > @@ -47,7 +47,7 @@ extern void __init update_regset_xstate_info(unsigned int size, > > void fpu__xstate_clear_all_cpu_caps(void); > void *get_xsave_addr(struct xregs_state *xsave, int xstate); and now I locally changed xstate to xfeature_nr. Sebastian
On 2018-10-17 12:01:43 [+0200], Borislav Petkov wrote: > > -void *__raw_xsave_addr(struct xregs_state *xsave, int xstate_feature_mask) > > +void *__raw_xsave_addr(struct xregs_state *xsave, int feature_nr) > > Don't forget to update the comment above it too - it still says "mask". done. > Otherwise nice. thanks. Sebastian
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) { - 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); } 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];
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(-)