From 072de836f53be56a70cecf70b43ae43b7ce17376 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Mon, 11 Dec 2023 10:08:36 +0000
Subject: [PATCH] mk-rootfs.sh
---
kernel/arch/x86/include/asm/cpufeature.h | 71 +++++++++++++++--------------------
1 files changed, 31 insertions(+), 40 deletions(-)
diff --git a/kernel/arch/x86/include/asm/cpufeature.h b/kernel/arch/x86/include/asm/cpufeature.h
index 5694825..f4cbc01 100644
--- a/kernel/arch/x86/include/asm/cpufeature.h
+++ b/kernel/arch/x86/include/asm/cpufeature.h
@@ -8,6 +8,7 @@
#include <asm/asm.h>
#include <linux/bitops.h>
+#include <asm/alternative.h>
enum cpuid_leafs
{
@@ -23,7 +24,7 @@
CPUID_7_0_EBX,
CPUID_D_1_EAX,
CPUID_LNX_4,
- CPUID_DUMMY,
+ CPUID_7_1_EAX,
CPUID_8000_0008_EBX,
CPUID_6_EAX,
CPUID_8000_000A_EDX,
@@ -49,7 +50,7 @@
extern const char * const x86_bug_flags[NBUGINTS*32];
#define test_cpu_cap(c, bit) \
- test_bit(bit, (unsigned long *)((c)->x86_capability))
+ arch_test_bit(bit, (unsigned long *)((c)->x86_capability))
/*
* There are 32 bits/features in each mask word. The high bits
@@ -61,6 +62,13 @@
#define CHECK_BIT_IN_MASK_WORD(maskname, word, bit) \
(((bit)>>5)==(word) && (1UL<<((bit)&31) & maskname##word ))
+/*
+ * {REQUIRED,DISABLED}_MASK_CHECK below may seem duplicated with the
+ * following BUILD_BUG_ON_ZERO() check but when NCAPINTS gets changed, all
+ * header macros which use NCAPINTS need to be changed. The duplicated macro
+ * use causes the compiler to issue errors for all headers so that all usage
+ * sites can be corrected.
+ */
#define REQUIRED_MASK_BIT_SET(feature_bit) \
( CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 0, feature_bit) || \
CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 1, feature_bit) || \
@@ -112,8 +120,9 @@
test_cpu_cap(c, bit))
#define this_cpu_has(bit) \
- (__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 : \
- x86_this_cpu_test_bit(bit, (unsigned long *)&cpu_info.x86_capability))
+ (__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 : \
+ x86_this_cpu_test_bit(bit, \
+ (unsigned long __percpu *)&cpu_info.x86_capability))
/*
* This macro is for detection of features which need kernel
@@ -146,51 +155,33 @@
* Workaround for the sake of BPF compilation which utilizes kernel
* headers, but clang does not support ASM GOTO and fails the build.
*/
+#ifndef __BPF_TRACING__
+#warning "Compiler lacks ASM_GOTO support. Add -D __BPF_TRACING__ to your compiler arguments"
+#endif
#define static_cpu_has(bit) boot_cpu_has(bit)
#else
/*
- * Static testing of CPU features. Used the same as boot_cpu_has().
- * These will statically patch the target code for additional
- * performance.
+ * Static testing of CPU features. Used the same as boot_cpu_has(). It
+ * statically patches the target code for additional performance. Use
+ * static_cpu_has() only in fast paths, where every cycle counts. Which
+ * means that the boot_cpu_has() variant is already fast enough for the
+ * majority of cases and you should stick to using it as it is generally
+ * only two instructions: a RIP-relative MOV and a TEST.
*/
-static __always_inline __pure bool _static_cpu_has(u16 bit)
+static __always_inline bool _static_cpu_has(u16 bit)
{
- asm_volatile_goto("1: jmp 6f\n"
- "2:\n"
- ".skip -(((5f-4f) - (2b-1b)) > 0) * "
- "((5f-4f) - (2b-1b)),0x90\n"
- "3:\n"
- ".section .altinstructions,\"a\"\n"
- " .long 1b - .\n" /* src offset */
- " .long 4f - .\n" /* repl offset */
- " .word %P[always]\n" /* always replace */
- " .byte 3b - 1b\n" /* src len */
- " .byte 5f - 4f\n" /* repl len */
- " .byte 3b - 2b\n" /* pad len */
- ".previous\n"
- ".section .altinstr_replacement,\"ax\"\n"
- "4: jmp %l[t_no]\n"
- "5:\n"
- ".previous\n"
- ".section .altinstructions,\"a\"\n"
- " .long 1b - .\n" /* src offset */
- " .long 0\n" /* no replacement */
- " .word %P[feature]\n" /* feature bit */
- " .byte 3b - 1b\n" /* src len */
- " .byte 0\n" /* repl len */
- " .byte 0\n" /* pad len */
- ".previous\n"
- ".section .altinstr_aux,\"ax\"\n"
- "6:\n"
- " testb %[bitnum],%[cap_byte]\n"
- " jnz %l[t_yes]\n"
- " jmp %l[t_no]\n"
- ".previous\n"
+ asm_volatile_goto(
+ ALTERNATIVE_TERNARY("jmp 6f", %P[feature], "", "jmp %l[t_no]")
+ ".section .altinstr_aux,\"ax\"\n"
+ "6:\n"
+ " testb %[bitnum],%[cap_byte]\n"
+ " jnz %l[t_yes]\n"
+ " jmp %l[t_no]\n"
+ ".previous\n"
: : [feature] "i" (bit),
- [always] "i" (X86_FEATURE_ALWAYS),
[bitnum] "i" (1 << (bit & 7)),
[cap_byte] "m" (((const char *)boot_cpu_data.x86_capability)[bit >> 3])
: : t_yes, t_no);
--
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