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Commit 0e861fbb authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
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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: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: KVM list <kvm@vger.kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: xen-devel <Xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/4085070316fc3ab29538d3fcfe282648d1d4ee2e.1459605520.git.luto@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 0d0efc07

arch/x86/include/asm/uaccess.h

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/head_32.S

+5 −44
Original line number Diff line number Diff line
@@ -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"



/*

arch/x86/kernel/head_64.S

+2 −43
Original line number Diff line number Diff line
@@ -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)

arch/x86/mm/extable.c

+24 −5
Original line number Diff line number Diff line
@@ -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();

}