From 18b13e5457041429af3974afd52f647c3a5465dd Mon Sep 17 00:00:00 2001 From: Eduardo Habkost <ehabkost@redhat.com> Date: Tue, 19 Aug 2008 20:00:08 -0300 Subject: KVM: Use .fixup instead of .text.fixup on __kvm_handle_fault_on_reboot vmlinux.lds expects the fixup code to be on a section named .fixup. The .text.fixup section is not mentioned on vmlinux.lds, and is included on the resulting vmlinux (just after .text) only because of ld heuristics on placing orphan sections. However, placing .text.fixup outside .text breaks the definition of _etext, making it exclude the .text.fixup contents. That makes .text.fixup be ignored by the kernel initialization code that needs to know about section locations, such as the code setting page protection bits. Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> Signed-off-by: Avi Kivity <avi@qumranet.com> --- include/asm-x86/kvm_host.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/asm-x86') diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h index 0f3c5311461..c2e34c27590 100644 --- a/include/asm-x86/kvm_host.h +++ b/include/asm-x86/kvm_host.h @@ -722,7 +722,7 @@ asmlinkage void kvm_handle_fault_on_reboot(void); #define __kvm_handle_fault_on_reboot(insn) \ "666: " insn "\n\t" \ - ".pushsection .text.fixup, \"ax\" \n" \ + ".pushsection .fixup, \"ax\" \n" \ "667: \n\t" \ KVM_EX_PUSH " $666b \n\t" \ "jmp kvm_handle_fault_on_reboot \n\t" \ -- cgit v1.2.3-70-g09d2 From b6734c35af028f06772c0b2c836c7d579e6d4dad Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" <hpa@zytor.com> Date: Mon, 18 Aug 2008 17:39:32 -0700 Subject: x86: add NOPL as a synthetic CPU feature bit The long noops ("NOPL") are supposed to be detected by family >= 6. Unfortunately, several non-Intel x86 implementations, both hardware and software, don't obey this dictum. Instead, probe for NOPL directly by executing a NOPL instruction and see if we get #UD. Signed-off-by: H. Peter Anvin <hpa@zytor.com> --- arch/x86/kernel/cpu/common.c | 32 +++++++++++++++++++++++++++++++- arch/x86/kernel/cpu/common_64.c | 36 ++++++++++++++++++++++++++++++++++++ arch/x86/kernel/cpu/feature_names.c | 3 ++- include/asm-x86/cpufeature.h | 11 ++++++----- include/asm-x86/required-features.h | 8 +++++++- 5 files changed, 82 insertions(+), 8 deletions(-) (limited to 'include/asm-x86') diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 80ab20d4fa3..0785b3c8d04 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -13,6 +13,7 @@ #include <asm/mtrr.h> #include <asm/mce.h> #include <asm/pat.h> +#include <asm/asm.h> #ifdef CONFIG_X86_LOCAL_APIC #include <asm/mpspec.h> #include <asm/apic.h> @@ -341,6 +342,35 @@ static void __init early_cpu_detect(void) early_get_cap(c); } +/* + * The NOPL instruction is supposed to exist on all CPUs with + * family >= 6, unfortunately, that's not true in practice because + * of early VIA chips and (more importantly) broken virtualizers that + * are not easy to detect. Hence, probe for it based on first + * principles. + */ +static void __cpuinit detect_nopl(struct cpuinfo_x86 *c) +{ + const u32 nopl_signature = 0x888c53b1; /* Random number */ + u32 has_nopl = nopl_signature; + + clear_cpu_cap(c, X86_FEATURE_NOPL); + if (c->x86 >= 6) { + asm volatile("\n" + "1: .byte 0x0f,0x1f,0xc0\n" /* nopl %eax */ + "2:\n" + " .section .fixup,\"ax\"\n" + "3: xor %0,%0\n" + " jmp 2b\n" + " .previous\n" + _ASM_EXTABLE(1b,3b) + : "+a" (has_nopl)); + + if (has_nopl == nopl_signature) + set_cpu_cap(c, X86_FEATURE_NOPL); + } +} + static void __cpuinit generic_identify(struct cpuinfo_x86 *c) { u32 tfms, xlvl; @@ -395,8 +425,8 @@ static void __cpuinit generic_identify(struct cpuinfo_x86 *c) } init_scattered_cpuid_features(c); + detect_nopl(c); } - } static void __cpuinit squash_the_stupid_serial_number(struct cpuinfo_x86 *c) diff --git a/arch/x86/kernel/cpu/common_64.c b/arch/x86/kernel/cpu/common_64.c index dd6e3f15017..c3afba5a81a 100644 --- a/arch/x86/kernel/cpu/common_64.c +++ b/arch/x86/kernel/cpu/common_64.c @@ -18,6 +18,7 @@ #include <asm/mtrr.h> #include <asm/mce.h> #include <asm/pat.h> +#include <asm/asm.h> #include <asm/numa.h> #ifdef CONFIG_X86_LOCAL_APIC #include <asm/mpspec.h> @@ -215,6 +216,39 @@ static void __init early_cpu_support_print(void) } } +/* + * The NOPL instruction is supposed to exist on all CPUs with + * family >= 6, unfortunately, that's not true in practice because + * of early VIA chips and (more importantly) broken virtualizers that + * are not easy to detect. Hence, probe for it based on first + * principles. + * + * Note: no 64-bit chip is known to lack these, but put the code here + * for consistency with 32 bits, and to make it utterly trivial to + * diagnose the problem should it ever surface. + */ +static void __cpuinit detect_nopl(struct cpuinfo_x86 *c) +{ + const u32 nopl_signature = 0x888c53b1; /* Random number */ + u32 has_nopl = nopl_signature; + + clear_cpu_cap(c, X86_FEATURE_NOPL); + if (c->x86 >= 6) { + asm volatile("\n" + "1: .byte 0x0f,0x1f,0xc0\n" /* nopl %eax */ + "2:\n" + " .section .fixup,\"ax\"\n" + "3: xor %0,%0\n" + " jmp 2b\n" + " .previous\n" + _ASM_EXTABLE(1b,3b) + : "+a" (has_nopl)); + + if (has_nopl == nopl_signature) + set_cpu_cap(c, X86_FEATURE_NOPL); + } +} + static void __cpuinit early_identify_cpu(struct cpuinfo_x86 *c); void __init early_cpu_init(void) @@ -313,6 +347,8 @@ static void __cpuinit early_identify_cpu(struct cpuinfo_x86 *c) c->x86_phys_bits = eax & 0xff; } + detect_nopl(c); + if (c->x86_vendor != X86_VENDOR_UNKNOWN && cpu_devs[c->x86_vendor]->c_early_init) cpu_devs[c->x86_vendor]->c_early_init(c); diff --git a/arch/x86/kernel/cpu/feature_names.c b/arch/x86/kernel/cpu/feature_names.c index e43ad4ad4cb..c9017799497 100644 --- a/arch/x86/kernel/cpu/feature_names.c +++ b/arch/x86/kernel/cpu/feature_names.c @@ -39,7 +39,8 @@ const char * const x86_cap_flags[NCAPINTS*32] = { NULL, NULL, NULL, NULL, "constant_tsc", "up", NULL, "arch_perfmon", "pebs", "bts", NULL, NULL, - "rep_good", NULL, NULL, NULL, NULL, NULL, NULL, NULL, + "rep_good", NULL, NULL, NULL, + "nopl", NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, /* Intel-defined (#2) */ diff --git a/include/asm-x86/cpufeature.h b/include/asm-x86/cpufeature.h index 762f6a6bc70..9489283a4bc 100644 --- a/include/asm-x86/cpufeature.h +++ b/include/asm-x86/cpufeature.h @@ -72,14 +72,15 @@ #define X86_FEATURE_UP (3*32+ 9) /* smp kernel running on up */ #define X86_FEATURE_FXSAVE_LEAK (3*32+10) /* FXSAVE leaks FOP/FIP/FOP */ #define X86_FEATURE_ARCH_PERFMON (3*32+11) /* Intel Architectural PerfMon */ -#define X86_FEATURE_PEBS (3*32+12) /* Precise-Event Based Sampling */ -#define X86_FEATURE_BTS (3*32+13) /* Branch Trace Store */ -#define X86_FEATURE_SYSCALL32 (3*32+14) /* syscall in ia32 userspace */ -#define X86_FEATURE_SYSENTER32 (3*32+15) /* sysenter in ia32 userspace */ +#define X86_FEATURE_PEBS (3*32+12) /* Precise-Event Based Sampling */ +#define X86_FEATURE_BTS (3*32+13) /* Branch Trace Store */ +#define X86_FEATURE_SYSCALL32 (3*32+14) /* syscall in ia32 userspace */ +#define X86_FEATURE_SYSENTER32 (3*32+15) /* sysenter in ia32 userspace */ #define X86_FEATURE_REP_GOOD (3*32+16) /* rep microcode works well on this CPU */ #define X86_FEATURE_MFENCE_RDTSC (3*32+17) /* Mfence synchronizes RDTSC */ #define X86_FEATURE_LFENCE_RDTSC (3*32+18) /* Lfence synchronizes RDTSC */ -#define X86_FEATURE_11AP (3*32+19) /* Bad local APIC aka 11AP */ +#define X86_FEATURE_11AP (3*32+19) /* Bad local APIC aka 11AP */ +#define X86_FEATURE_NOPL (3*32+20) /* The NOPL (0F 1F) instructions */ /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */ #define X86_FEATURE_XMM3 (4*32+ 0) /* Streaming SIMD Extensions-3 */ diff --git a/include/asm-x86/required-features.h b/include/asm-x86/required-features.h index adec887dd7c..5c2ff4bc298 100644 --- a/include/asm-x86/required-features.h +++ b/include/asm-x86/required-features.h @@ -41,6 +41,12 @@ # define NEED_3DNOW 0 #endif +#if defined(CONFIG_X86_P6_NOP) || defined(CONFIG_X86_64) +# define NEED_NOPL (1<<(X86_FEATURE_NOPL & 31)) +#else +# define NEED_NOPL 0 +#endif + #ifdef CONFIG_X86_64 #define NEED_PSE 0 #define NEED_MSR (1<<(X86_FEATURE_MSR & 31)) @@ -67,7 +73,7 @@ #define REQUIRED_MASK1 (NEED_LM|NEED_3DNOW) #define REQUIRED_MASK2 0 -#define REQUIRED_MASK3 0 +#define REQUIRED_MASK3 (NEED_NOPL) #define REQUIRED_MASK4 0 #define REQUIRED_MASK5 0 #define REQUIRED_MASK6 0 -- cgit v1.2.3-70-g09d2