x86/fpu: Rename xfeatures_mask_user() to xfeatures_mask_uabi()

Rename it so it's clear that this is about user ABI features which can
differ from the feature set which the kernel saves and restores because the
kernel handles e.g. PKRU differently. But the user ABI (ptrace, signal
frame) expects it to be there.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121456.211585137@linutronix.de

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 63d979656437c9f9f6ca978d9d44907a9b23fbad..bcfb6365a76bd9ddc0eed05f8c487037bbc8fe33 100644 (file)
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -324,7 +324,12 @@ static inline void os_xrstor(struct xregs_state *xstate, u64 mask)
  */
 static inline int xsave_to_user_sigframe(struct xregs_state __user *buf)
 {
-       u64 mask = xfeatures_mask_user();
+       /*
+        * Include the features which are not xsaved/rstored by the kernel
+        * internally, e.g. PKRU. That's user space ABI and also required
+        * to allow the signal handler to modify PKRU.
+        */
+       u64 mask = xfeatures_mask_uabi();
        u32 lmask = mask;
        u32 hmask = mask >> 32;
        int err;

diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index 5764cbe390148adc9981314956e9fbbea7ea8af0..af9ea134bf5e6af5e3a5019d816d07ac74360211 100644 (file)
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -83,7 +83,11 @@ static inline u64 xfeatures_mask_supervisor(void)
        return xfeatures_mask_all & XFEATURE_MASK_SUPERVISOR_SUPPORTED;
 }
 
-static inline u64 xfeatures_mask_user(void)
+/*
+ * The xfeatures which are enabled in XCR0 and expected to be in ptrace
+ * buffers and signal frames.
+ */
+static inline u64 xfeatures_mask_uabi(void)
 {
        return xfeatures_mask_all & XFEATURE_MASK_USER_SUPPORTED;
 }

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index afd0deee8cfdd032d7e432eac235e843d26a4d06..12437383ff79fb51e93c4e63f9174730241e67be 100644 (file)
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -404,7 +404,7 @@ void fpu__clear_user_states(struct fpu *fpu)
        }
 
        /* Reset user states in registers. */
-       restore_fpregs_from_init_fpstate(xfeatures_mask_user());
+       restore_fpregs_from_init_fpstate(xfeatures_mask_uabi());
 
        /*
         * Now all FPU registers have their desired values.  Inform the FPU

diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index b12665c38a302634c2d6df05455241ccd089be82..a42bc9d0b1cc570e1dc5946e9432014cab261065 100644 (file)
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -257,14 +257,14 @@ static int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
 
        if (use_xsave()) {
                if (fx_only) {
-                       init_bv = xfeatures_mask_user() & ~XFEATURE_MASK_FPSSE;
+                       init_bv = xfeatures_mask_uabi() & ~XFEATURE_MASK_FPSSE;
 
                        r = fxrstor_from_user_sigframe(buf);
                        if (!r)
                                os_xrstor(&init_fpstate.xsave, init_bv);
                        return r;
                } else {
-                       init_bv = xfeatures_mask_user() & ~xbv;
+                       init_bv = xfeatures_mask_uabi() & ~xbv;
 
                        r = xrstor_from_user_sigframe(buf, xbv);
                        if (!r && unlikely(init_bv))
@@ -420,7 +420,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
        fpregs_unlock();
 
        if (use_xsave() && !fx_only) {
-               u64 init_bv = xfeatures_mask_user() & ~user_xfeatures;
+               u64 init_bv = xfeatures_mask_uabi() & ~user_xfeatures;
 
                ret = copy_sigframe_from_user_to_xstate(&fpu->state.xsave, buf_fx);
                if (ret)
@@ -454,7 +454,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
                if (use_xsave()) {
                        u64 init_bv;
 
-                       init_bv = xfeatures_mask_user() & ~XFEATURE_MASK_FPSSE;
+                       init_bv = xfeatures_mask_uabi() & ~XFEATURE_MASK_FPSSE;
                        os_xrstor(&init_fpstate.xsave, init_bv);
                }
 
@@ -549,7 +549,7 @@ void fpu__init_prepare_fx_sw_frame(void)
 
        fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
        fx_sw_reserved.extended_size = size;
-       fx_sw_reserved.xfeatures = xfeatures_mask_user();
+       fx_sw_reserved.xfeatures = xfeatures_mask_uabi();
        fx_sw_reserved.xstate_size = fpu_user_xstate_size;
 
        if (IS_ENABLED(CONFIG_IA32_EMULATION) ||

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index bc71609ba65a3b9ec85cb8bef462127edacd93ee..c513596f8ec912e84dd50864e1e41457d85ec6d8 100644 (file)
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -144,7 +144,7 @@ void fpu__init_cpu_xstate(void)
         * managed by XSAVE{C, OPT, S} and XRSTOR{S}.  Only XSAVE user
         * states can be set here.
         */
-       xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_user());
+       xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_uabi());
 
        /*
         * MSR_IA32_XSS sets supervisor states managed by XSAVES.
@@ -453,7 +453,7 @@ int xfeature_size(int xfeature_nr)
 static int validate_user_xstate_header(const struct xstate_header *hdr)
 {
        /* No unknown or supervisor features may be set */
-       if (hdr->xfeatures & ~xfeatures_mask_user())
+       if (hdr->xfeatures & ~xfeatures_mask_uabi())
                return -EINVAL;
 
        /* Userspace must use the uncompacted format */
@@ -756,7 +756,7 @@ void __init fpu__init_system_xstate(void)
        cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
        xfeatures_mask_all |= ecx + ((u64)edx << 32);
 
-       if ((xfeatures_mask_user() & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
+       if ((xfeatures_mask_uabi() & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
                /*
                 * This indicates that something really unexpected happened
                 * with the enumeration.  Disable XSAVE and try to continue
@@ -791,7 +791,7 @@ void __init fpu__init_system_xstate(void)
         * Update info used for ptrace frames; use standard-format size and no
         * supervisor xstates:
         */
-       update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask_user());
+       update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask_uabi());
 
        fpu__init_prepare_fx_sw_frame();
        setup_init_fpu_buf();
@@ -828,14 +828,14 @@ void fpu__resume_cpu(void)
        /*
         * Restore XCR0 on xsave capable CPUs:
         */
-       if (boot_cpu_has(X86_FEATURE_XSAVE))
-               xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_user());
+       if (cpu_feature_enabled(X86_FEATURE_XSAVE))
+               xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_uabi());
 
        /*
         * Restore IA32_XSS. The same CPUID bit enumerates support
         * of XSAVES and MSR_IA32_XSS.
         */
-       if (boot_cpu_has(X86_FEATURE_XSAVES)) {
+       if (cpu_feature_enabled(X86_FEATURE_XSAVES)) {
                wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor()  |
                                     xfeatures_mask_independent());
        }
@@ -993,7 +993,7 @@ void copy_xstate_to_uabi_buf(struct membuf to, struct xregs_state *xsave,
                break;
 
        case XSTATE_COPY_XSAVE:
-               header.xfeatures &= xfeatures_mask_user();
+               header.xfeatures &= xfeatures_mask_uabi();
                break;
        }
 
@@ -1038,7 +1038,7 @@ void copy_xstate_to_uabi_buf(struct membuf to, struct xregs_state *xsave,
                 * compacted init_fpstate. The gap tracking will zero this
                 * later.
                 */
-               if (!(xfeatures_mask_user() & BIT_ULL(i)))
+               if (!(xfeatures_mask_uabi() & BIT_ULL(i)))
                        continue;
 
                /*