| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <tip-9900aa2f95844eb81428c1d3d202c01b7f3ac77a@git.kernel.org> Date: Thu, 19 Apr 2012 17:28:04 -0700 From: "tip-bot for H. Peter Anvin" <hpa@...or.com> To: linux-tip-commits@...r.kernel.org Cc: linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org, tglx@...utronix.de, hpa@...ux.intel.com Subject: [tip:x86/extable] x86-64: Handle exception table entries during early boot Commit-ID: 9900aa2f95844eb81428c1d3d202c01b7f3ac77a Gitweb: http://git.kernel.org/tip/9900aa2f95844eb81428c1d3d202c01b7f3ac77a Author: H. Peter Anvin <hpa@...or.com> AuthorDate: Wed, 18 Apr 2012 17:16:49 -0700 Committer: H. Peter Anvin <hpa@...ux.intel.com> CommitDate: Thu, 19 Apr 2012 15:42:45 -0700 x86-64: Handle exception table entries during early boot If we get an exception during early boot, walk the exception table to see if we should intercept it. The main use case for this is to allow rdmsr_safe()/wrmsr_safe() during CPU initialization. Since the exception table is currently sorted at runtime, and fairly late in startup, this code walks the exception table linearly. We obviously don't need to worry about modules, however: none have been loaded at this point. [ v2: Use early_fixup_exception() instead of linear search ] Link: http://lkml.kernel.org/r/1334794610-5546-5-git-send-email-hpa@zytor.com Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com> --- arch/x86/include/asm/segment.h | 2 +- arch/x86/kernel/head_64.S | 76 ++++++++++++++++++++++++++++++---------- 2 files changed, 58 insertions(+), 20 deletions(-) diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h index 58c1e6c..c48a950 100644 --- a/arch/x86/include/asm/segment.h +++ b/arch/x86/include/asm/segment.h @@ -213,7 +213,7 @@ #ifdef __KERNEL__ #ifndef __ASSEMBLY__ -extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][10]; +extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][2+2+5]; /* * Load a segment. Fall back on loading the zero diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index d1e112c..7a40f24 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -19,6 +19,7 @@ #include <asm/cache.h> #include <asm/processor-flags.h> #include <asm/percpu.h> +#include <asm/nops.h> #ifdef CONFIG_PARAVIRT #include <asm/asm-offsets.h> @@ -26,6 +27,7 @@ #define GET_CR2_INTO(reg) GET_CR2_INTO_RAX ; movq %rax, reg #else #define GET_CR2_INTO(reg) movq %cr2, reg +#define INTERRUPT_RETURN iretq #endif /* we are not able to switch in one step to the final KERNEL ADDRESS SPACE @@ -271,35 +273,56 @@ bad_address: jmp bad_address .section ".init.text","ax" -#ifdef CONFIG_EARLY_PRINTK .globl early_idt_handlers early_idt_handlers: + # 104(%rsp) %rflags + # 96(%rsp) %cs + # 88(%rsp) %rip + # 80(%rsp) error code i = 0 .rept NUM_EXCEPTION_VECTORS - movl $i, %esi + .if (EXCEPTION_ERRCODE_MASK >> i) & 1 + ASM_NOP2 + .else + pushq $0 # Dummy error code, to make stack frame uniform + .endif + pushq $i # 72(%rsp) Vector number jmp early_idt_handler i = i + 1 .endr -#endif ENTRY(early_idt_handler) -#ifdef CONFIG_EARLY_PRINTK + cld + cmpl $2,early_recursion_flag(%rip) jz 1f incl early_recursion_flag(%rip) - GET_CR2_INTO(%r9) - xorl %r8d,%r8d # zero for error code - movl %esi,%ecx # get vector number - # Test %ecx against mask of vectors that push error code. - cmpl $31,%ecx - ja 0f - movl $1,%eax - salq %cl,%rax - testl $EXCEPTION_ERRCODE_MASK,%eax - je 0f - popq %r8 # get error code -0: movq 0(%rsp),%rcx # get ip - movq 8(%rsp),%rdx # get cs + + pushq %rax # 64(%rsp) + pushq %rcx # 56(%rsp) + pushq %rdx # 48(%rsp) + pushq %rsi # 40(%rsp) + pushq %rdi # 32(%rsp) + pushq %r8 # 24(%rsp) + pushq %r9 # 16(%rsp) + pushq %r10 # 8(%rsp) + pushq %r11 # 0(%rsp) + + cmpl $__KERNEL_CS,96(%rsp) + jne 10f + + leaq 88(%rsp),%rdi # Pointer to %rip + call early_fixup_exception + andl %eax,%eax + jnz 20f # Found an exception entry + +10: +#ifdef CONFIG_EARLY_PRINTK + GET_CR2_INTO(%r9) # can clobber any volatile register if pv + movl 80(%rsp),%r8d # error code + movl 72(%rsp),%esi # vector number + movl 96(%rsp),%edx # %cs + movq 88(%rsp),%rcx # %rip xorl %eax,%eax leaq early_idt_msg(%rip),%rdi call early_printk @@ -308,17 +331,32 @@ ENTRY(early_idt_handler) call dump_stack #ifdef CONFIG_KALLSYMS leaq early_idt_ripmsg(%rip),%rdi - movq 0(%rsp),%rsi # get rip again + movq 40(%rsp),%rsi # %rip again call __print_symbol #endif #endif /* EARLY_PRINTK */ 1: hlt jmp 1b -#ifdef CONFIG_EARLY_PRINTK +20: # Exception table entry found + popq %r11 + popq %r10 + popq %r9 + popq %r8 + popq %rdi + popq %rsi + popq %rdx + popq %rcx + popq %rax + addq $16,%rsp # drop vector number and error code + decl early_recursion_flag(%rip) + INTERRUPT_RETURN + + .balign 4 early_recursion_flag: .long 0 +#ifdef CONFIG_EARLY_PRINTK early_idt_msg: .asciz "PANIC: early exception %02lx rip %lx:%lx error %lx cr2 %lx\n" early_idt_ripmsg: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists