From 01573e231f18eb2d99162747186f59511f56b64d Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Fri, 08 Dec 2023 10:40:48 +0000
Subject: [PATCH] 移去rt
---
kernel/arch/x86/include/asm/special_insns.h | 180 +++++++++++++++++++++++++++++++++++++++++-------------------
1 files changed, 123 insertions(+), 57 deletions(-)
diff --git a/kernel/arch/x86/include/asm/special_insns.h b/kernel/arch/x86/include/asm/special_insns.h
index 317fc59..415693f 100644
--- a/kernel/arch/x86/include/asm/special_insns.h
+++ b/kernel/arch/x86/include/asm/special_insns.h
@@ -6,50 +6,52 @@
#ifdef __KERNEL__
#include <asm/nops.h>
+#include <asm/processor-flags.h>
+#include <linux/irqflags.h>
+#include <linux/jump_label.h>
/*
- * Volatile isn't enough to prevent the compiler from reordering the
- * read/write functions for the control registers and messing everything up.
- * A memory clobber would solve the problem, but would prevent reordering of
- * all loads stores around it, which can hurt performance. Solution is to
- * use a variable and mimic reads and writes to it to enforce serialization
+ * The compiler should not reorder volatile asm statements with respect to each
+ * other: they should execute in program order. However GCC 4.9.x and 5.x have
+ * a bug (which was fixed in 8.1, 7.3 and 6.5) where they might reorder
+ * volatile asm. The write functions are not affected since they have memory
+ * clobbers preventing reordering. To prevent reads from being reordered with
+ * respect to writes, use a dummy memory operand.
*/
-extern unsigned long __force_order;
+
+#define __FORCE_ORDER "m"(*(unsigned int *)0x1000UL)
+
+void native_write_cr0(unsigned long val);
static inline unsigned long native_read_cr0(void)
{
unsigned long val;
- asm volatile("mov %%cr0,%0\n\t" : "=r" (val), "=m" (__force_order));
+ asm volatile("mov %%cr0,%0\n\t" : "=r" (val) : __FORCE_ORDER);
return val;
}
-static inline void native_write_cr0(unsigned long val)
-{
- asm volatile("mov %0,%%cr0": : "r" (val), "m" (__force_order));
-}
-
-static inline unsigned long native_read_cr2(void)
+static __always_inline unsigned long native_read_cr2(void)
{
unsigned long val;
- asm volatile("mov %%cr2,%0\n\t" : "=r" (val), "=m" (__force_order));
+ asm volatile("mov %%cr2,%0\n\t" : "=r" (val) : __FORCE_ORDER);
return val;
}
-static inline void native_write_cr2(unsigned long val)
+static __always_inline void native_write_cr2(unsigned long val)
{
- asm volatile("mov %0,%%cr2": : "r" (val), "m" (__force_order));
+ asm volatile("mov %0,%%cr2": : "r" (val) : "memory");
}
static inline unsigned long __native_read_cr3(void)
{
unsigned long val;
- asm volatile("mov %%cr3,%0\n\t" : "=r" (val), "=m" (__force_order));
+ asm volatile("mov %%cr3,%0\n\t" : "=r" (val) : __FORCE_ORDER);
return val;
}
static inline void native_write_cr3(unsigned long val)
{
- asm volatile("mov %0,%%cr3": : "r" (val), "m" (__force_order));
+ asm volatile("mov %0,%%cr3": : "r" (val) : "memory");
}
static inline unsigned long native_read_cr4(void)
@@ -64,35 +66,18 @@
asm volatile("1: mov %%cr4, %0\n"
"2:\n"
_ASM_EXTABLE(1b, 2b)
- : "=r" (val), "=m" (__force_order) : "0" (0));
+ : "=r" (val) : "0" (0), __FORCE_ORDER);
#else
/* CR4 always exists on x86_64. */
- asm volatile("mov %%cr4,%0\n\t" : "=r" (val), "=m" (__force_order));
+ asm volatile("mov %%cr4,%0\n\t" : "=r" (val) : __FORCE_ORDER);
#endif
return val;
}
-static inline void native_write_cr4(unsigned long val)
-{
- asm volatile("mov %0,%%cr4": : "r" (val), "m" (__force_order));
-}
-
-#ifdef CONFIG_X86_64
-static inline unsigned long native_read_cr8(void)
-{
- unsigned long cr8;
- asm volatile("movq %%cr8,%0" : "=r" (cr8));
- return cr8;
-}
-
-static inline void native_write_cr8(unsigned long val)
-{
- asm volatile("movq %0,%%cr8" :: "r" (val) : "memory");
-}
-#endif
+void native_write_cr4(unsigned long val);
#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
-static inline u32 __read_pkru(void)
+static inline u32 rdpkru(void)
{
u32 ecx = 0;
u32 edx, pkru;
@@ -107,7 +92,7 @@
return pkru;
}
-static inline void __write_pkru(u32 pkru)
+static inline void wrpkru(u32 pkru)
{
u32 ecx = 0, edx = 0;
@@ -118,8 +103,21 @@
asm volatile(".byte 0x0f,0x01,0xef\n\t"
: : "a" (pkru), "c"(ecx), "d"(edx));
}
+
+static inline void __write_pkru(u32 pkru)
+{
+ /*
+ * WRPKRU is relatively expensive compared to RDPKRU.
+ * Avoid WRPKRU when it would not change the value.
+ */
+ if (pkru == rdpkru())
+ return;
+
+ wrpkru(pkru);
+}
+
#else
-static inline u32 __read_pkru(void)
+static inline u32 rdpkru(void)
{
return 0;
}
@@ -134,14 +132,23 @@
asm volatile("wbinvd": : :"memory");
}
-extern asmlinkage void native_load_gs_index(unsigned);
+extern asmlinkage void asm_load_gs_index(unsigned int selector);
+
+static inline void native_load_gs_index(unsigned int selector)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ asm_load_gs_index(selector);
+ local_irq_restore(flags);
+}
static inline unsigned long __read_cr4(void)
{
return native_read_cr4();
}
-#ifdef CONFIG_PARAVIRT
+#ifdef CONFIG_PARAVIRT_XXL
#include <asm/paravirt.h>
#else
@@ -155,12 +162,12 @@
native_write_cr0(x);
}
-static inline unsigned long read_cr2(void)
+static __always_inline unsigned long read_cr2(void)
{
return native_read_cr2();
}
-static inline void write_cr2(unsigned long x)
+static __always_inline void write_cr2(unsigned long x)
{
native_write_cr2(x);
}
@@ -191,24 +198,14 @@
#ifdef CONFIG_X86_64
-static inline unsigned long read_cr8(void)
-{
- return native_read_cr8();
-}
-
-static inline void write_cr8(unsigned long x)
-{
- native_write_cr8(x);
-}
-
-static inline void load_gs_index(unsigned selector)
+static inline void load_gs_index(unsigned int selector)
{
native_load_gs_index(selector);
}
#endif
-#endif/* CONFIG_PARAVIRT */
+#endif /* CONFIG_PARAVIRT_XXL */
static inline void clflush(volatile void *__p)
{
@@ -239,6 +236,75 @@
#define nop() asm volatile ("nop")
+static inline void serialize(void)
+{
+ /* Instruction opcode for SERIALIZE; supported in binutils >= 2.35. */
+ asm volatile(".byte 0xf, 0x1, 0xe8" ::: "memory");
+}
+
+/* The dst parameter must be 64-bytes aligned */
+static inline void movdir64b(void *dst, const void *src)
+{
+ const struct { char _[64]; } *__src = src;
+ struct { char _[64]; } *__dst = dst;
+
+ /*
+ * MOVDIR64B %(rdx), rax.
+ *
+ * Both __src and __dst must be memory constraints in order to tell the
+ * compiler that no other memory accesses should be reordered around
+ * this one.
+ *
+ * Also, both must be supplied as lvalues because this tells
+ * the compiler what the object is (its size) the instruction accesses.
+ * I.e., not the pointers but what they point to, thus the deref'ing '*'.
+ */
+ asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
+ : "+m" (*__dst)
+ : "m" (*__src), "a" (__dst), "d" (__src));
+}
+
+/**
+ * enqcmds - Enqueue a command in supervisor (CPL0) mode
+ * @dst: destination, in MMIO space (must be 512-bit aligned)
+ * @src: 512 bits memory operand
+ *
+ * The ENQCMDS instruction allows software to write a 512-bit command to
+ * a 512-bit-aligned special MMIO region that supports the instruction.
+ * A return status is loaded into the ZF flag in the RFLAGS register.
+ * ZF = 0 equates to success, and ZF = 1 indicates retry or error.
+ *
+ * This function issues the ENQCMDS instruction to submit data from
+ * kernel space to MMIO space, in a unit of 512 bits. Order of data access
+ * is not guaranteed, nor is a memory barrier performed afterwards. It
+ * returns 0 on success and -EAGAIN on failure.
+ *
+ * Warning: Do not use this helper unless your driver has checked that the
+ * ENQCMDS instruction is supported on the platform and the device accepts
+ * ENQCMDS.
+ */
+static inline int enqcmds(void __iomem *dst, const void *src)
+{
+ const struct { char _[64]; } *__src = src;
+ struct { char _[64]; } __iomem *__dst = dst;
+ bool zf;
+
+ /*
+ * ENQCMDS %(rdx), rax
+ *
+ * See movdir64b()'s comment on operand specification.
+ */
+ asm volatile(".byte 0xf3, 0x0f, 0x38, 0xf8, 0x02, 0x66, 0x90"
+ CC_SET(z)
+ : CC_OUT(z) (zf), "+m" (*__dst)
+ : "m" (*__src), "a" (__dst), "d" (__src));
+
+ /* Submission failure is indicated via EFLAGS.ZF=1 */
+ if (zf)
+ return -EAGAIN;
+
+ return 0;
+}
#endif /* __KERNEL__ */
--
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