x86-64: don't set the early IDT to point directly to 'early_idt_handler' (ac630dd9) · Commits · 戴 / test

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 : "x86, 64bit: Use a #PF handler to materialize early mappings on demand") for the page fault exception vector. Acked-by:

H. Peter Anvin <hpa@zytor.com> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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

Admin message