[patch 11/31] x86/fpu/xstate: Provide and use for_each_xfeature()

Thomas Gleixner
2021-10-12T00:06:28Z

These loops evaluating xfeature bits are really hard to read. Create an
iterator and use for_each_set_bit_from() inside which already does the right
thing.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/fpu/xstate.c | 56 +++++++++++++++++--------------------------
1 file changed, 23 insertions(+), 33 deletions(-)

--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -4,6 +4,7 @@
*
* Author: Suresh Siddha <suresh.b.siddha@intel.com>
*/
+#include <linux/bitops.h>
#include <linux/compat.h>
#include <linux/cpu.h>
#include <linux/mman.h>
@@ -20,6 +21,10 @@

#include "xstate.h"

+#define for_each_extended_xfeature(bit, mask) \
+ (bit) = FIRST_EXTENDED_XFEATURE; \
+ for_each_set_bit_from(bit, (unsigned long *)&(mask), 8 * sizeof(mask))
+
/*
* Although we spell it out in here, the Processor Trace
* xfeature is completely unused. We use other mechanisms
@@ -184,10 +189,7 @@ static void __init setup_xstate_features
xstate_sizes[XFEATURE_SSE] = sizeof_field(struct fxregs_state,
xmm_space);

- for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
- if (!xfeature_enabled(i))
- continue;
-
+ for_each_extended_xfeature(i, xfeatures_mask_all) {
cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);

xstate_sizes[i] = eax;
@@ -291,20 +293,15 @@ static void __init setup_xstate_comp_off
xstate_comp_offsets[XFEATURE_SSE] = offsetof(struct fxregs_state,
xmm_space);

- if (!boot_cpu_has(X86_FEATURE_XSAVES)) {
- for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
- if (xfeature_enabled(i))
- xstate_comp_offsets[i] = xstate_offsets[i];
- }
+ if (!cpu_feature_enabled(X86_FEATURE_XSAVES)) {
+ for_each_extended_xfeature(i, xfeatures_mask_all)
+ xstate_comp_offsets[i] = xstate_offsets[i];
return;
}

next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE;

- for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
- if (!xfeature_enabled(i))
- continue;
-
+ for_each_extended_xfeature(i, xfeatures_mask_all) {
if (xfeature_is_aligned(i))
next_offset = ALIGN(next_offset, 64);

@@ -328,8 +325,8 @@ static void __init setup_supervisor_only

next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE;

- for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
- if (!xfeature_enabled(i) || !xfeature_is_supervisor(i))
+ for_each_extended_xfeature(i, xfeatures_mask_all) {
+ if (!xfeature_is_supervisor(i))
continue;

if (xfeature_is_aligned(i))
@@ -347,9 +344,7 @@ static void __init print_xstate_offset_s
{
int i;

- for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
- if (!xfeature_enabled(i))
- continue;
+ for_each_extended_xfeature(i, xfeatures_mask_all) {
pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n",
i, xstate_comp_offsets[i], i, xstate_sizes[i]);
}
@@ -554,10 +549,7 @@ static void do_extra_xstate_size_checks(
int paranoid_xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
int i;

- for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
- if (!xfeature_enabled(i))
- continue;
-
+ for_each_extended_xfeature(i, xfeatures_mask_all) {
check_xstate_against_struct(i);
/*
* Supervisor state components can be managed only by
@@ -586,7 +578,6 @@ static void do_extra_xstate_size_checks(
XSTATE_WARN_ON(paranoid_xstate_size != fpu_kernel_xstate_size);
}

-
/*
* Get total size of enabled xstates in XCR0 | IA32_XSS.
*
@@ -969,6 +960,7 @@ void copy_xstate_to_uabi_buf(struct memb
struct xregs_state *xinit = &init_fpstate.xsave;
struct xstate_header header;
unsigned int zerofrom;
+ u64 mask;
int i;

memset(&header, 0, sizeof(header));
@@ -1022,17 +1014,15 @@ void copy_xstate_to_uabi_buf(struct memb

zerofrom = offsetof(struct xregs_state, extended_state_area);

- for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
- /*
- * The ptrace buffer is in non-compacted XSAVE format.
- * In non-compacted format disabled features still occupy
- * state space, but there is no state to copy from in the
- * compacted init_fpstate. The gap tracking will zero this
- * later.
- */
- if (!(xfeatures_mask_uabi() & BIT_ULL(i)))
- continue;
+ /*
+ * The ptrace buffer is in non-compacted XSAVE format. In
+ * non-compacted format disabled features still occupy state space,
+ * but there is no state to copy from in the compacted
+ * init_fpstate. The gap tracking will zero these states.
+ */
+ mask = xfeatures_mask_uabi();

+ for_each_extended_xfeature(i, mask) {
/*
* If there was a feature or alignment gap, zero the space
* in the destination buffer.