Commit-ID: 0e861fbb5bda79b871341ef2a9a8059765cbe8a4 Gitweb: http://git.kernel.org/tip/0e861fbb5bda79b871341ef2a9a8059765cbe8a4 Author: Andy Lutomirski <luto@xxxxxxxxxx> AuthorDate: Sat, 2 Apr 2016 07:01:34 -0700 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Wed, 13 Apr 2016 11:37:44 +0200 x86/head: Move early exception panic code into early_fixup_exception() This removes a bunch of assembly and adds some C code instead. It changes the actual printouts on both 32-bit and 64-bit kernels, but they still seem okay. Tested-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx> Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: KVM list <kvm@xxxxxxxxxxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: xen-devel <Xen-devel@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/4085070316fc3ab29538d3fcfe282648d1d4ee2e.1459605520.git.luto@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/include/asm/uaccess.h | 2 +- arch/x86/kernel/head_32.S | 49 +++++------------------------------------- arch/x86/kernel/head_64.S | 45 ++------------------------------------ arch/x86/mm/extable.c | 29 ++++++++++++++++++++----- 4 files changed, 32 insertions(+), 93 deletions(-) diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index b6fb311..d794fd1 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -110,7 +110,7 @@ struct exception_table_entry { extern int fixup_exception(struct pt_regs *regs, int trapnr); extern bool ex_has_fault_handler(unsigned long ip); -extern int early_fixup_exception(struct pt_regs *regs, int trapnr); +extern void early_fixup_exception(struct pt_regs *regs, int trapnr); /* * These are the main single-value transfer routines. They automatically diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 184291c..6770865 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -561,8 +561,6 @@ early_idt_handler_common: */ cld - cmpl $2,%ss:early_recursion_flag - je hlt_loop incl %ss:early_recursion_flag /* The vector number is in pt_regs->gs */ @@ -594,13 +592,8 @@ early_idt_handler_common: movw %gs, PT_GS(%esp) movw $0, PT_GS+2(%esp) - cmpl $(__KERNEL_CS),PT_CS(%esp) - jne 10f - movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */ call early_fixup_exception - andl %eax,%eax - jz 10f /* Exception wasn't fixed up */ popl %ebx /* pt_regs->bx */ popl %ecx /* pt_regs->cx */ @@ -616,29 +609,6 @@ early_idt_handler_common: decl %ss:early_recursion_flag addl $4, %esp /* pop pt_regs->orig_ax */ iret - -10: -#ifdef CONFIG_PRINTK - xorl %eax,%eax - movw %ax,PT_FS+2(%esp) /* clean up the segment values on some cpus */ - movw %ax,PT_DS+2(%esp) - movw %ax,PT_ES+2(%esp) - leal 40(%esp),%eax - pushl %eax /* %esp before the exception */ - pushl %ebx - pushl %ebp - pushl %esi - pushl %edi - movl %cr2,%eax - pushl %eax - pushl (20+6*4)(%esp) /* trapno */ - pushl $fault_msg - call printk -#endif - call dump_stack -hlt_loop: - hlt - jmp hlt_loop ENDPROC(early_idt_handler_common) /* This is the default interrupt "handler" :-) */ @@ -674,10 +644,14 @@ ignore_int: popl %eax #endif iret + +hlt_loop: + hlt + jmp hlt_loop ENDPROC(ignore_int) __INITDATA .align 4 -early_recursion_flag: +GLOBAL(early_recursion_flag) .long 0 __REFDATA @@ -742,19 +716,6 @@ __INITRODATA int_msg: .asciz "Unknown interrupt or fault at: %p %p %p\n" -fault_msg: -/* fault info: */ - .ascii "BUG: Int %d: CR2 %p\n" -/* regs pushed in early_idt_handler: */ - .ascii " EDI %p ESI %p EBP %p EBX %p\n" - .ascii " ESP %p ES %p DS %p\n" - .ascii " EDX %p ECX %p EAX %p\n" -/* fault frame: */ - .ascii " vec %p err %p EIP %p CS %p flg %p\n" - .ascii "Stack: %p %p %p %p %p %p %p %p\n" - .ascii " %p %p %p %p %p %p %p %p\n" - .asciz " %p %p %p %p %p %p %p %p\n" - #include "../../x86/xen/xen-head.S" /* diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 2308437..3de91a7 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -351,8 +351,6 @@ early_idt_handler_common: */ cld - cmpl $2,early_recursion_flag(%rip) - jz 1f incl early_recursion_flag(%rip) /* The vector number is currently in the pt_regs->di slot. */ @@ -373,9 +371,6 @@ early_idt_handler_common: pushq %r14 /* pt_regs->r14 */ pushq %r15 /* pt_regs->r15 */ - cmpl $__KERNEL_CS,CS(%rsp) - jne 11f - cmpq $14,%rsi /* Page fault? */ jnz 10f GET_CR2_INTO(%rdi) /* Can clobber any volatile register if pv */ @@ -386,37 +381,8 @@ early_idt_handler_common: 10: movq %rsp,%rdi /* RDI = pt_regs; RSI is already trapnr */ call early_fixup_exception - andl %eax,%eax - jnz 20f # Found an exception entry - -11: -#ifdef CONFIG_EARLY_PRINTK - /* - * On paravirt kernels, GET_CR2_INTO clobbers callee-clobbered regs. - * We only care about RSI, so we need to save it. - */ - movq %rsi,%rbx /* Save vector number */ - GET_CR2_INTO(%r9) - movq ORIG_RAX(%rsp),%r8 /* error code */ - movq %rbx,%rsi /* vector number */ - movq CS(%rsp),%rdx - movq RIP(%rsp),%rcx - xorl %eax,%eax - leaq early_idt_msg(%rip),%rdi - call early_printk - cmpl $2,early_recursion_flag(%rip) - jz 1f - call dump_stack -#ifdef CONFIG_KALLSYMS - leaq early_idt_ripmsg(%rip),%rdi - movq RIP(%rsp),%rsi # %rip again - call __print_symbol -#endif -#endif /* EARLY_PRINTK */ -1: hlt - jmp 1b -20: /* Exception table entry found or page table generated */ +20: decl early_recursion_flag(%rip) jmp restore_regs_and_iret ENDPROC(early_idt_handler_common) @@ -424,16 +390,9 @@ ENDPROC(early_idt_handler_common) __INITDATA .balign 4 -early_recursion_flag: +GLOBAL(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: - .asciz "RIP %s\n" -#endif /* CONFIG_EARLY_PRINTK */ - #define NEXT_PAGE(name) \ .balign PAGE_SIZE; \ GLOBAL(name) diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index 4be0419..da442f3 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -83,8 +83,10 @@ int fixup_exception(struct pt_regs *regs, int trapnr) return handler(e, regs, trapnr); } +extern unsigned int early_recursion_flag; + /* Restricted version used during very early boot */ -int __init early_fixup_exception(struct pt_regs *regs, int trapnr) +void __init early_fixup_exception(struct pt_regs *regs, int trapnr) { const struct exception_table_entry *e; unsigned long new_ip; @@ -92,19 +94,36 @@ int __init early_fixup_exception(struct pt_regs *regs, int trapnr) /* Ignore early NMIs. */ if (trapnr == X86_TRAP_NMI) - return 1; + return; + + if (early_recursion_flag > 2) + goto halt_loop; + + if (regs->cs != __KERNEL_CS) + goto fail; e = search_exception_tables(regs->ip); if (!e) - return 0; + goto fail; new_ip = ex_fixup_addr(e); handler = ex_fixup_handler(e); /* special handling not supported during early boot */ if (handler != ex_handler_default) - return 0; + goto fail; regs->ip = new_ip; - return 1; + return; + +fail: + early_printk("PANIC: early exception 0x%02x IP %lx:%lx error %lx cr2 0x%lx\n", + (unsigned)trapnr, (unsigned long)regs->cs, regs->ip, + regs->orig_ax, read_cr2()); + + show_regs(regs); + +halt_loop: + while (true) + halt(); } -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
