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author | H. Peter Anvin <hpa@zytor.com> | 2012-04-18 17:16:49 -0700 |
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committer | H. Peter Anvin <hpa@linux.intel.com> | 2012-04-19 15:42:45 -0700 |
commit | 9900aa2f95844eb81428c1d3d202c01b7f3ac77a (patch) | |
tree | 4c93c0eebb8e645e0de8aa767913f6c4f14f1b75 /arch/x86/kernel/head_64.S | |
parent | 6a1ea279c210e7dc05de86dc29c0d4f577f484fb (diff) | |
download | op-kernel-dev-9900aa2f95844eb81428c1d3d202c01b7f3ac77a.zip op-kernel-dev-9900aa2f95844eb81428c1d3d202c01b7f3ac77a.tar.gz |
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@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/head_64.S')
-rw-r--r-- | arch/x86/kernel/head_64.S | 76 |
1 files changed, 57 insertions, 19 deletions
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index d1e112c8..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: |