diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2017-10-16 12:12:16 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2017-10-16 20:47:37 +0200 |
| commit | 9c48c0965b97e14ddcf75490a754e84e05aaa062 (patch) | |
| tree | 1a24a02d690d967b29fbd65a21211fd4c4d8d6ab /arch | |
| parent | e6fc454b7794fc45c27364c7896b8f03094635ee (diff) | |
x86/idt: Initialize early IDT before cr4_init_shadow()
Moving the early IDT setup out of assembly code breaks the boot on first
generation 486 systems.
The reason is that the call of idt_setup_early_handler, which sets up the
early handlers was added after the call to cr4_init_shadow().
cr4_init_shadow() tries to read CR4 which is not available on those
systems. The accessor function uses a extable fixup to handle the resulting
fault. As the IDT is not set up yet, the cr4 read exception causes an
instantaneous reboot for obvious reasons.
Call idt_setup_early_handler() before cr4_init_shadow() so IDT is set up
before the first exception hits.
Fixes: 87e81786b13b ("x86/idt: Move early IDT setup out of 32-bit asm")
Reported-and-tested-by: Matthew Whitehead <whiteheadm@acm.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1710161210290.1973@nanos
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/head32.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c index cf2ce063f65a..2902ca4d5993 100644 --- a/arch/x86/kernel/head32.c +++ b/arch/x86/kernel/head32.c @@ -30,10 +30,11 @@ static void __init i386_default_early_setup(void) asmlinkage __visible void __init i386_start_kernel(void) { - cr4_init_shadow(); - + /* Make sure IDT is set up before any exception happens */ idt_setup_early_handler(); + cr4_init_shadow(); + sanitize_boot_params(&boot_params); x86_early_init_platform_quirks(); |