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 8170e6bed465: "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>
diff --git a/arch/x86/include/asm/proto.h b/arch/x86/include/asm/proto.h
index 6f414ed..6fd3fd7 100644
--- a/arch/x86/include/asm/proto.h
+++ b/arch/x86/include/asm/proto.h
@@ -5,8 +5,6 @@
/* misc architecture specific prototypes */
-void early_idt_handler(void);
-
void system_call(void);
void syscall_init(void);
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 57334f4c..2590025 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -159,13 +159,8 @@
/* 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));
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index d94f6d6..b7de3b2 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -336,6 +336,7 @@
i = i + 1
.endr
+/* This is global to keep gas from relaxing the jumps */
ENTRY(early_idt_handler)
cld
@@ -404,6 +405,7 @@
addq $16,%rsp # drop vector number and error code
decl early_recursion_flag(%rip)
INTERRUPT_RETURN
+ENDPROC(early_idt_handler)
__INITDATA