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/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