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Commit ac630dd9 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

x86-64: don't set the early IDT to point directly to 'early_idt_handler' 



The code requires the use of the proper per-exception-vector stub
functions (set up as the early_idt_handlers[] array - note the 's') that
make sure to set up the error vector number.  This is true regardless of
whether CONFIG_EARLY_PRINTK is set or not.

Why? The stack offset for the comparison of __KERNEL_CS won't be right
otherwise, nor will the new check (from commit 8170e6be: "x86,
64bit: Use a #PF handler to materialize early mappings on demand") for
the page fault exception vector.

Acked-by: default avatarH. Peter Anvin <hpa@zytor.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2ef14f46

arch/x86/include/asm/proto.h

+0 −2
Original line number Diff line number Diff line
@@ -5,8 +5,6 @@ 


/* misc architecture specific prototypes */



void early_idt_handler(void);



void system_call(void);

void syscall_init(void);

arch/x86/kernel/head64.c

+1 −6
Original line number Diff line number Diff line
@@ -159,13 +159,8 @@ void __init x86_64_start_kernel(char * real_mode_data) 
	/* clear bss before set_intr_gate with early_idt_handler */

	clear_bss();



	for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) {

#ifdef CONFIG_EARLY_PRINTK

	for (i = 0; i < NUM_EXCEPTION_VECTORS; i++)

		set_intr_gate(i, &early_idt_handlers[i]);

#else

		set_intr_gate(i, early_idt_handler);

#endif

	}

	load_idt((const struct desc_ptr *)&idt_descr);



	copy_bootdata(__va(real_mode_data));

arch/x86/kernel/head_64.S

+2 −0
Original line number Diff line number Diff line
@@ -336,6 +336,7 @@ early_idt_handlers: 
	i = i + 1

	.endr



/* This is global to keep gas from relaxing the jumps */

ENTRY(early_idt_handler)

	cld
@@ -404,6 +405,7 @@ ENTRY(early_idt_handler) 
	addq $16,%rsp		# drop vector number and error code

	decl early_recursion_flag(%rip)

	INTERRUPT_RETURN

ENDPROC(early_idt_handler)



	__INITDATA