Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753185Ab3JATiz (ORCPT ); Tue, 1 Oct 2013 15:38:55 -0400 Received: from smtp.outflux.net ([198.145.64.163]:42932 "EHLO smtp.outflux.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751784Ab3JAThx (ORCPT ); Tue, 1 Oct 2013 15:37:53 -0400 From: Kees Cook To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, kernel-hardening@lists.openwall.com, adurbin@google.com, Eric Northup , jln@google.com, wad@google.com, Mathias Krause , Zhang Yanfei , "H. Peter Anvin" , keescook@chromium.org Subject: [PATCH 1/7] x86, kaslr: move CPU flags out of cpucheck Date: Tue, 1 Oct 2013 12:37:19 -0700 Message-Id: <1380656245-29975-2-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1380656245-29975-1-git-send-email-keescook@chromium.org> References: <1380656245-29975-1-git-send-email-keescook@chromium.org> X-HELO: www.outflux.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8950 Lines: 342 Refactor the CPU flags handling out of the cpucheck routines so that they can be reused by the future ASLR routines (in order to detect CPU features like RDRAND and RDTSC). This reworks has_eflag() and has_fpu() to be used on both 32-bit and 64-bit, and refactors the calls to cpuid to make them PIC-safe on 32-bit. Signed-off-by: Kees Cook --- arch/x86/boot/Makefile | 2 +- arch/x86/boot/boot.h | 10 +--- arch/x86/boot/compressed/Makefile | 2 +- arch/x86/boot/compressed/cpuflags.c | 12 ++++ arch/x86/boot/cpucheck.c | 86 ----------------------------- arch/x86/boot/cpuflags.c | 104 +++++++++++++++++++++++++++++++++++ arch/x86/boot/cpuflags.h | 19 +++++++ 7 files changed, 138 insertions(+), 97 deletions(-) create mode 100644 arch/x86/boot/compressed/cpuflags.c create mode 100644 arch/x86/boot/cpuflags.c create mode 100644 arch/x86/boot/cpuflags.h diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile index 379814b..0da2e37 100644 --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -20,7 +20,7 @@ targets := vmlinux.bin setup.bin setup.elf bzImage targets += fdimage fdimage144 fdimage288 image.iso mtools.conf subdir- := compressed -setup-y += a20.o bioscall.o cmdline.o copy.o cpu.o cpucheck.o +setup-y += a20.o bioscall.o cmdline.o copy.o cpu.o cpuflags.o cpucheck.o setup-y += early_serial_console.o edd.o header.o main.o mca.o memory.o setup-y += pm.o pmjump.o printf.o regs.o string.o tty.o video.o setup-y += video-mode.o version.o diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h index ef72bae..50f8c5e 100644 --- a/arch/x86/boot/boot.h +++ b/arch/x86/boot/boot.h @@ -26,9 +26,8 @@ #include #include #include "bitops.h" -#include -#include #include "ctype.h" +#include "cpuflags.h" /* Useful macros */ #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)])) @@ -307,14 +306,7 @@ static inline int cmdline_find_option_bool(const char *option) return __cmdline_find_option_bool(cmd_line_ptr, option); } - /* cpu.c, cpucheck.c */ -struct cpu_features { - int level; /* Family, or 64 for x86-64 */ - int model; - u32 flags[NCAPINTS]; -}; -extern struct cpu_features cpu; int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr); int validate_cpu(void); diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index dcd90df..3312f1b 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -27,7 +27,7 @@ HOST_EXTRACFLAGS += -I$(srctree)/tools/include VMLINUX_OBJS = $(obj)/vmlinux.lds $(obj)/head_$(BITS).o $(obj)/misc.o \ $(obj)/string.o $(obj)/cmdline.o $(obj)/early_serial_console.o \ - $(obj)/piggy.o + $(obj)/piggy.o $(obj)/cpuflags.o $(obj)/eboot.o: KBUILD_CFLAGS += -fshort-wchar -mno-red-zone diff --git a/arch/x86/boot/compressed/cpuflags.c b/arch/x86/boot/compressed/cpuflags.c new file mode 100644 index 0000000..931cba6 --- /dev/null +++ b/arch/x86/boot/compressed/cpuflags.c @@ -0,0 +1,12 @@ +#ifdef CONFIG_RANDOMIZE_BASE + +#include "../cpuflags.c" + +bool has_cpuflag(int flag) +{ + get_flags(); + + return test_bit(flag, cpu.flags); +} + +#endif diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c index 4d3ff03..e1f3c16 100644 --- a/arch/x86/boot/cpucheck.c +++ b/arch/x86/boot/cpucheck.c @@ -28,8 +28,6 @@ #include #include -struct cpu_features cpu; -static u32 cpu_vendor[3]; static u32 err_flags[NCAPINTS]; static const int req_level = CONFIG_X86_MINIMUM_CPU_FAMILY; @@ -69,90 +67,6 @@ static int is_transmeta(void) cpu_vendor[2] == A32('M', 'x', '8', '6'); } -static int has_fpu(void) -{ - u16 fcw = -1, fsw = -1; - u32 cr0; - - asm("movl %%cr0,%0" : "=r" (cr0)); - if (cr0 & (X86_CR0_EM|X86_CR0_TS)) { - cr0 &= ~(X86_CR0_EM|X86_CR0_TS); - asm volatile("movl %0,%%cr0" : : "r" (cr0)); - } - - asm volatile("fninit ; fnstsw %0 ; fnstcw %1" - : "+m" (fsw), "+m" (fcw)); - - return fsw == 0 && (fcw & 0x103f) == 0x003f; -} - -static int has_eflag(u32 mask) -{ - u32 f0, f1; - - asm("pushfl ; " - "pushfl ; " - "popl %0 ; " - "movl %0,%1 ; " - "xorl %2,%1 ; " - "pushl %1 ; " - "popfl ; " - "pushfl ; " - "popl %1 ; " - "popfl" - : "=&r" (f0), "=&r" (f1) - : "ri" (mask)); - - return !!((f0^f1) & mask); -} - -static void get_flags(void) -{ - u32 max_intel_level, max_amd_level; - u32 tfms; - - if (has_fpu()) - set_bit(X86_FEATURE_FPU, cpu.flags); - - if (has_eflag(X86_EFLAGS_ID)) { - asm("cpuid" - : "=a" (max_intel_level), - "=b" (cpu_vendor[0]), - "=d" (cpu_vendor[1]), - "=c" (cpu_vendor[2]) - : "a" (0)); - - if (max_intel_level >= 0x00000001 && - max_intel_level <= 0x0000ffff) { - asm("cpuid" - : "=a" (tfms), - "=c" (cpu.flags[4]), - "=d" (cpu.flags[0]) - : "a" (0x00000001) - : "ebx"); - cpu.level = (tfms >> 8) & 15; - cpu.model = (tfms >> 4) & 15; - if (cpu.level >= 6) - cpu.model += ((tfms >> 16) & 0xf) << 4; - } - - asm("cpuid" - : "=a" (max_amd_level) - : "a" (0x80000000) - : "ebx", "ecx", "edx"); - - if (max_amd_level >= 0x80000001 && - max_amd_level <= 0x8000ffff) { - u32 eax = 0x80000001; - asm("cpuid" - : "+a" (eax), - "=c" (cpu.flags[6]), - "=d" (cpu.flags[1]) - : : "ebx"); - } - } -} - /* Returns a bitmask of which words we have error bits in */ static int check_flags(void) { diff --git a/arch/x86/boot/cpuflags.c b/arch/x86/boot/cpuflags.c new file mode 100644 index 0000000..b02544a --- /dev/null +++ b/arch/x86/boot/cpuflags.c @@ -0,0 +1,104 @@ +#include +#include "bitops.h" + +#include +#include +#include +#include "cpuflags.h" + +struct cpu_features cpu; +u32 cpu_vendor[3]; + +static bool loaded_flags; + +static int has_fpu(void) +{ + u16 fcw = -1, fsw = -1; + unsigned long cr0; + + asm volatile("mov %%cr0,%0" : "=r" (cr0)); + if (cr0 & (X86_CR0_EM|X86_CR0_TS)) { + cr0 &= ~(X86_CR0_EM|X86_CR0_TS); + asm volatile("mov %0,%%cr0" : : "r" (cr0)); + } + + asm volatile("fninit ; fnstsw %0 ; fnstcw %1" + : "+m" (fsw), "+m" (fcw)); + + return fsw == 0 && (fcw & 0x103f) == 0x003f; +} + +int has_eflag(unsigned long mask) +{ + unsigned long f0, f1; + + asm volatile("pushf \n\t" + "pushf \n\t" + "pop %0 \n\t" + "mov %0,%1 \n\t" + "xor %2,%1 \n\t" + "push %1 \n\t" + "popf \n\t" + "pushf \n\t" + "pop %1 \n\t" + "popf" + : "=&r" (f0), "=&r" (f1) + : "ri" (mask)); + + return !!((f0^f1) & mask); +} + +/* Handle x86_32 PIC using ebx. */ +#if defined(__i386__) && defined(__PIC__) +# define EBX_REG "=r" +#else +# define EBX_REG "=b" +#endif + +static inline void cpuid(u32 id, u32 *a, u32 *b, u32 *c, u32 *d) +{ + asm volatile(".ifnc %%ebx,%3 ; movl %%ebx,%3 ; .endif \n\t" + "cpuid \n\t" + ".ifnc %%ebx,%3 ; xchgl %%ebx,%3 ; .endif \n\t" + : "=a" (*a), "=c" (*c), "=d" (*d), EBX_REG (*b) + : "a" (id) + ); +} + +void get_flags(void) +{ + u32 max_intel_level, max_amd_level; + u32 tfms; + u32 ignored; + + if (loaded_flags) + return; + loaded_flags = true; + + if (has_fpu()) + set_bit(X86_FEATURE_FPU, cpu.flags); + + if (has_eflag(X86_EFLAGS_ID)) { + cpuid(0x0, &max_intel_level, &cpu_vendor[0], &cpu_vendor[2], + &cpu_vendor[1]); + + if (max_intel_level >= 0x00000001 && + max_intel_level <= 0x0000ffff) { + cpuid(0x1, &tfms, &ignored, &cpu.flags[4], + &cpu.flags[0]); + cpu.level = (tfms >> 8) & 15; + cpu.model = (tfms >> 4) & 15; + if (cpu.level >= 6) + cpu.model += ((tfms >> 16) & 0xf) << 4; + } + + cpuid(0x80000000, &max_amd_level, &ignored, &ignored, + &ignored); + + if (max_amd_level >= 0x80000001 && + max_amd_level <= 0x8000ffff) { + cpuid(0x80000001, &ignored, &ignored, &cpu.flags[6], + &cpu.flags[1]); + } + } +} diff --git a/arch/x86/boot/cpuflags.h b/arch/x86/boot/cpuflags.h new file mode 100644 index 0000000..9bb4e25 --- /dev/null +++ b/arch/x86/boot/cpuflags.h @@ -0,0 +1,19 @@ +#ifndef BOOT_CPUFLAGS_H +#define BOOT_CPUFLAGS_H + +#include +#include + +struct cpu_features { + int level; /* Family, or 64 for x86-64 */ + int model; + u32 flags[NCAPINTS]; +}; + +extern struct cpu_features cpu; +extern u32 cpu_vendor[3]; + +int has_eflag(unsigned long mask); +void get_flags(void); + +#endif -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/