x86/fpu/xstate: Provide and use for_each_xfeature()

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.

No functional changes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011538.958107505@linutronix.de

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 259951d..a2bdc0c 100644 (file)
--- 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(void)
        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_offsets(void)
        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_offsets(void)
 
        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_size(void)
 {
        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(void)
        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(void)
        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 membuf to, struct task_struct *tsk,
        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 membuf to, struct task_struct *tsk,
 
        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.