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x86/idt: Add comments about early #PF handling

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The difference between 32 and 64 bit vs. early #PF handling is not
documented. Replace the FIXME at idt_setup_early_pf() with proper comments.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200528145522.807135882@linutronix.de
This commit is contained in:
Thomas Gleixner 2020-05-28 16:53:17 +02:00
parent bdf5bde8ae
commit 94438af40d
1 changed files with 8 additions and 2 deletions
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10
arch/x86/kernel/idt.c
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@ -61,7 +61,11 @@ static bool idt_setup_done __initdata;
static const __initconst struct idt_data early_idts[] = { static const __initconst struct idt_data early_idts[] = {
INTG(X86_TRAP_DB, asm_exc_debug), INTG(X86_TRAP_DB, asm_exc_debug),
SYSG(X86_TRAP_BP, asm_exc_int3), SYSG(X86_TRAP_BP, asm_exc_int3),
#ifdef CONFIG_X86_32 #ifdef CONFIG_X86_32
/*
* Not possible on 64-bit. See idt_setup_early_pf() for details.
*/
INTG(X86_TRAP_PF, asm_exc_page_fault), INTG(X86_TRAP_PF, asm_exc_page_fault),
#endif #endif
}; };
@ -256,8 +260,10 @@ void __init idt_setup_traps(void)
* cpu_init() is invoked and sets up TSS. The IST variant is installed * cpu_init() is invoked and sets up TSS. The IST variant is installed
* after that. * after that.
* *
* FIXME: Why is 32bit and 64bit installing the PF handler at different * Note, that X86_64 cannot install the real #PF handler in
* places in the early setup code? * idt_setup_early_traps() because the memory intialization needs the #PF
* handler from the early_idt_handler_array to initialize the early page
* tables.
*/ */
void __init idt_setup_early_pf(void) void __init idt_setup_early_pf(void)
{ {