From 093a6c67005148ae32a5c9e4553491b9f5c2457b Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Fri, 10 May 2024 07:40:51 +0000
Subject: [PATCH] disable kernel build waring
---
kernel/arch/x86/include/asm/fpu/internal.h | 267 +++++++++++++++++++++++++---------------------------
1 files changed, 128 insertions(+), 139 deletions(-)
diff --git a/kernel/arch/x86/include/asm/fpu/internal.h b/kernel/arch/x86/include/asm/fpu/internal.h
index 4f274d8..94c0715 100644
--- a/kernel/arch/x86/include/asm/fpu/internal.h
+++ b/kernel/arch/x86/include/asm/fpu/internal.h
@@ -14,27 +14,27 @@
#include <linux/compat.h>
#include <linux/sched.h>
#include <linux/slab.h>
+#include <linux/mm.h>
#include <asm/user.h>
#include <asm/fpu/api.h>
#include <asm/fpu/xstate.h>
+#include <asm/fpu/xcr.h>
#include <asm/cpufeature.h>
#include <asm/trace/fpu.h>
/*
* High level FPU state handling functions:
*/
-extern void fpu__initialize(struct fpu *fpu);
extern void fpu__prepare_read(struct fpu *fpu);
extern void fpu__prepare_write(struct fpu *fpu);
extern void fpu__save(struct fpu *fpu);
-extern void fpu__restore(struct fpu *fpu);
extern int fpu__restore_sig(void __user *buf, int ia32_frame);
extern void fpu__drop(struct fpu *fpu);
-extern int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu);
-extern void fpu__clear(struct fpu *fpu);
+extern int fpu__copy(struct task_struct *dst, struct task_struct *src);
+extern void fpu__clear_user_states(struct fpu *fpu);
+extern void fpu__clear_all(struct fpu *fpu);
extern int fpu__exception_code(struct fpu *fpu, int trap_nr);
-extern int dump_fpu(struct pt_regs *ptregs, struct user_i387_struct *fpstate);
/*
* Boot time FPU initialization functions:
@@ -42,7 +42,7 @@
extern void fpu__init_cpu(void);
extern void fpu__init_system_xstate(void);
extern void fpu__init_cpu_xstate(void);
-extern void fpu__init_system(struct cpuinfo_x86 *c);
+extern void fpu__init_system(void);
extern void fpu__init_check_bugs(void);
extern void fpu__resume_cpu(void);
extern u64 fpu__get_supported_xfeatures_mask(void);
@@ -93,7 +93,7 @@
* XRSTORS requires these bits set in xcomp_bv, or it will
* trigger #GP:
*/
- xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xfeatures_mask;
+ xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xfeatures_mask_all;
}
static inline void fpstate_init_fxstate(struct fxregs_state *fx)
@@ -123,6 +123,21 @@
err; \
})
+#define kernel_insn_err(insn, output, input...) \
+({ \
+ int err; \
+ asm volatile("1:" #insn "\n\t" \
+ "2:\n" \
+ ".section .fixup,\"ax\"\n" \
+ "3: movl $-1,%[err]\n" \
+ " jmp 2b\n" \
+ ".previous\n" \
+ _ASM_EXTABLE(1b, 3b) \
+ : [err] "=r" (err), output \
+ : "0"(0), input); \
+ err; \
+})
+
#define kernel_insn(insn, output, input...) \
asm volatile("1:" #insn "\n\t" \
"2:\n" \
@@ -138,42 +153,43 @@
{
if (IS_ENABLED(CONFIG_X86_32))
return user_insn(fxsave %[fx], [fx] "=m" (*fx), "m" (*fx));
- else if (IS_ENABLED(CONFIG_AS_FXSAVEQ))
+ else
return user_insn(fxsaveq %[fx], [fx] "=m" (*fx), "m" (*fx));
- /* See comment in copy_fxregs_to_kernel() below. */
- return user_insn(rex64/fxsave (%[fx]), "=m" (*fx), [fx] "R" (fx));
}
static inline void copy_kernel_to_fxregs(struct fxregs_state *fx)
{
- if (IS_ENABLED(CONFIG_X86_32)) {
+ if (IS_ENABLED(CONFIG_X86_32))
kernel_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
- } else {
- if (IS_ENABLED(CONFIG_AS_FXSAVEQ)) {
- kernel_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
- } else {
- /* See comment in copy_fxregs_to_kernel() below. */
- kernel_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx), "m" (*fx));
- }
- }
+ else
+ kernel_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
+}
+
+static inline int copy_kernel_to_fxregs_err(struct fxregs_state *fx)
+{
+ if (IS_ENABLED(CONFIG_X86_32))
+ return kernel_insn_err(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+ else
+ return kernel_insn_err(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
}
static inline int copy_user_to_fxregs(struct fxregs_state __user *fx)
{
if (IS_ENABLED(CONFIG_X86_32))
return user_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
- else if (IS_ENABLED(CONFIG_AS_FXSAVEQ))
+ else
return user_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
-
- /* See comment in copy_fxregs_to_kernel() below. */
- return user_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx),
- "m" (*fx));
}
static inline void copy_kernel_to_fregs(struct fregs_state *fx)
{
kernel_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+}
+
+static inline int copy_kernel_to_fregs_err(struct fregs_state *fx)
+{
+ return kernel_insn_err(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
}
static inline int copy_user_to_fregs(struct fregs_state __user *fx)
@@ -185,34 +201,8 @@
{
if (IS_ENABLED(CONFIG_X86_32))
asm volatile( "fxsave %[fx]" : [fx] "=m" (fpu->state.fxsave));
- else if (IS_ENABLED(CONFIG_AS_FXSAVEQ))
+ else
asm volatile("fxsaveq %[fx]" : [fx] "=m" (fpu->state.fxsave));
- else {
- /* Using "rex64; fxsave %0" is broken because, if the memory
- * operand uses any extended registers for addressing, a second
- * REX prefix will be generated (to the assembler, rex64
- * followed by semicolon is a separate instruction), and hence
- * the 64-bitness is lost.
- *
- * Using "fxsaveq %0" would be the ideal choice, but is only
- * supported starting with gas 2.16.
- *
- * Using, as a workaround, the properly prefixed form below
- * isn't accepted by any binutils version so far released,
- * complaining that the same type of prefix is used twice if
- * an extended register is needed for addressing (fix submitted
- * to mainline 2005-11-21).
- *
- * asm volatile("rex64/fxsave %0" : "=m" (fpu->state.fxsave));
- *
- * This, however, we can work around by forcing the compiler to
- * select an addressing mode that doesn't require extended
- * registers.
- */
- asm volatile( "rex64/fxsave (%[fx])"
- : "=m" (fpu->state.fxsave)
- : [fx] "R" (&fpu->state.fxsave));
- }
}
static inline void fxsave(struct fxregs_state *fx)
@@ -304,7 +294,7 @@
WARN_ON(system_state != SYSTEM_BOOTING);
- if (static_cpu_has(X86_FEATURE_XSAVES))
+ if (boot_cpu_has(X86_FEATURE_XSAVES))
XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
else
XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
@@ -321,7 +311,7 @@
*/
static inline void copy_xregs_to_kernel(struct xregs_state *xstate)
{
- u64 mask = -1;
+ u64 mask = xfeatures_mask_all;
u32 lmask = mask;
u32 hmask = mask >> 32;
int err;
@@ -357,6 +347,9 @@
*/
static inline int copy_xregs_to_user(struct xregs_state __user *buf)
{
+ u64 mask = xfeatures_mask_user();
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
int err;
/*
@@ -368,7 +361,7 @@
return -EFAULT;
stac();
- XSTATE_OP(XSAVE, buf, -1, -1, err);
+ XSTATE_OP(XSAVE, buf, lmask, hmask, err);
clac();
return err;
@@ -392,35 +385,24 @@
}
/*
- * These must be called with preempt disabled. Returns
- * 'true' if the FPU state is still intact and we can
- * keep registers active.
- *
- * The legacy FNSAVE instruction cleared all FPU state
- * unconditionally, so registers are essentially destroyed.
- * Modern FPU state can be kept in registers, if there are
- * no pending FP exceptions.
+ * Restore xstate from kernel space xsave area, return an error code instead of
+ * an exception.
*/
-static inline int copy_fpregs_to_fpstate(struct fpu *fpu)
+static inline int copy_kernel_to_xregs_err(struct xregs_state *xstate, u64 mask)
{
- if (likely(use_xsave())) {
- copy_xregs_to_kernel(&fpu->state.xsave);
- return 1;
- }
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+ int err;
- if (likely(use_fxsr())) {
- copy_fxregs_to_kernel(fpu);
- return 1;
- }
+ if (static_cpu_has(X86_FEATURE_XSAVES))
+ XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
+ else
+ XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
- /*
- * Legacy FPU register saving, FNSAVE always clears FPU registers,
- * so we have to mark them inactive:
- */
- asm volatile("fnsave %[fp]; fwait" : [fp] "=m" (fpu->state.fsave));
-
- return 0;
+ return err;
}
+
+extern int copy_fpregs_to_fpstate(struct fpu *fpu);
static inline void __copy_kernel_to_fpregs(union fpregs_state *fpstate, u64 mask)
{
@@ -489,7 +471,7 @@
static inline int fpregs_state_valid(struct fpu *fpu, unsigned int cpu)
{
- return fpu == this_cpu_read_stable(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu;
+ return fpu == this_cpu_read(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu;
}
/*
@@ -509,6 +491,25 @@
}
/*
+ * Internal helper, do not use directly. Use switch_fpu_return() instead.
+ */
+static inline void __fpregs_load_activate(void)
+{
+ struct fpu *fpu = ¤t->thread.fpu;
+ int cpu = smp_processor_id();
+
+ if (WARN_ON_ONCE(current->flags & PF_KTHREAD))
+ return;
+
+ if (!fpregs_state_valid(fpu, cpu)) {
+ copy_kernel_to_fpregs(&fpu->state);
+ fpregs_activate(fpu);
+ fpu->last_cpu = cpu;
+ }
+ clear_thread_flag(TIF_NEED_FPU_LOAD);
+}
+
+/*
* FPU state switching for scheduling.
*
* This is a two-stage process:
@@ -516,13 +517,25 @@
* - switch_fpu_prepare() saves the old state.
* This is done within the context of the old process.
*
- * - switch_fpu_finish() restores the new state as
- * necessary.
+ * - switch_fpu_finish() sets TIF_NEED_FPU_LOAD; the floating point state
+ * will get loaded on return to userspace, or when the kernel needs it.
+ *
+ * If TIF_NEED_FPU_LOAD is cleared then the CPU's FPU registers
+ * are saved in the current thread's FPU register state.
+ *
+ * If TIF_NEED_FPU_LOAD is set then CPU's FPU registers may not
+ * hold current()'s FPU registers. It is required to load the
+ * registers before returning to userland or using the content
+ * otherwise.
+ *
+ * The FPU context is only stored/restored for a user task and
+ * PF_KTHREAD is used to distinguish between kernel and user threads.
*/
-static inline void
-switch_fpu_prepare(struct fpu *old_fpu, int cpu)
+static inline void switch_fpu_prepare(struct task_struct *prev, int cpu)
{
- if (static_cpu_has(X86_FEATURE_FPU) && old_fpu->initialized) {
+ struct fpu *old_fpu = &prev->thread.fpu;
+
+ if (static_cpu_has(X86_FEATURE_FPU) && !(prev->flags & PF_KTHREAD)) {
if (!copy_fpregs_to_fpstate(old_fpu))
old_fpu->last_cpu = -1;
else
@@ -530,8 +543,7 @@
/* But leave fpu_fpregs_owner_ctx! */
trace_x86_fpu_regs_deactivated(old_fpu);
- } else
- old_fpu->last_cpu = -1;
+ }
}
/*
@@ -539,63 +551,40 @@
*/
/*
- * Set up the userspace FPU context for the new task, if the task
- * has used the FPU.
+ * Load PKRU from the FPU context if available. Delay loading of the
+ * complete FPU state until the return to userland.
*/
-static inline void switch_fpu_finish(struct fpu *new_fpu, int cpu)
+static inline void switch_fpu_finish(struct task_struct *next)
{
- bool preload = static_cpu_has(X86_FEATURE_FPU) &&
- new_fpu->initialized;
+ u32 pkru_val = init_pkru_value;
+ struct pkru_state *pk;
+ struct fpu *next_fpu = &next->thread.fpu;
- if (preload) {
- if (!fpregs_state_valid(new_fpu, cpu))
- copy_kernel_to_fpregs(&new_fpu->state);
- fpregs_activate(new_fpu);
+ if (!static_cpu_has(X86_FEATURE_FPU))
+ return;
+
+ set_thread_flag(TIF_NEED_FPU_LOAD);
+
+ if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
+ return;
+
+ /*
+ * PKRU state is switched eagerly because it needs to be valid before we
+ * return to userland e.g. for a copy_to_user() operation.
+ */
+ if (!(next->flags & PF_KTHREAD)) {
+ /*
+ * If the PKRU bit in xsave.header.xfeatures is not set,
+ * then the PKRU component was in init state, which means
+ * XRSTOR will set PKRU to 0. If the bit is not set then
+ * get_xsave_addr() will return NULL because the PKRU value
+ * in memory is not valid. This means pkru_val has to be
+ * set to 0 and not to init_pkru_value.
+ */
+ pk = get_xsave_addr(&next_fpu->state.xsave, XFEATURE_PKRU);
+ pkru_val = pk ? pk->pkru : 0;
}
-}
-
-/*
- * Needs to be preemption-safe.
- *
- * NOTE! user_fpu_begin() must be used only immediately before restoring
- * the save state. It does not do any saving/restoring on its own. In
- * lazy FPU mode, it is just an optimization to avoid a #NM exception,
- * the task can lose the FPU right after preempt_enable().
- */
-static inline void user_fpu_begin(void)
-{
- struct fpu *fpu = ¤t->thread.fpu;
-
- preempt_disable();
- fpregs_activate(fpu);
- preempt_enable();
-}
-
-/*
- * MXCSR and XCR definitions:
- */
-
-extern unsigned int mxcsr_feature_mask;
-
-#define XCR_XFEATURE_ENABLED_MASK 0x00000000
-
-static inline u64 xgetbv(u32 index)
-{
- u32 eax, edx;
-
- asm volatile(".byte 0x0f,0x01,0xd0" /* xgetbv */
- : "=a" (eax), "=d" (edx)
- : "c" (index));
- return eax + ((u64)edx << 32);
-}
-
-static inline void xsetbv(u32 index, u64 value)
-{
- u32 eax = value;
- u32 edx = value >> 32;
-
- asm volatile(".byte 0x0f,0x01,0xd1" /* xsetbv */
- : : "a" (eax), "d" (edx), "c" (index));
+ __write_pkru(pkru_val);
}
#endif /* _ASM_X86_FPU_INTERNAL_H */
--
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