Commit 03dda951 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Borislav Petkov (AMD)
Browse files

x86/decompressor: Merge trampoline cleanup with switching code 



Now that the trampoline setup code and the actual invocation of it are
all done from the C routine, the trampoline cleanup can be merged into
it as well, instead of returning to asm just to call another C function.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/r/20230807162720.545787-16-ardb@kernel.org
parent cb83cece

arch/x86/boot/compressed/head_64.S

+4 −10
Original line number Diff line number Diff line
@@ -430,20 +430,14 @@ SYM_CODE_START(startup_64) 
	 * a trampoline in 32-bit addressable memory if the current number does

	 * not match the desired number.

	 *

	 * Pass the boot_params pointer as the first argument.

	 * Pass the boot_params pointer as the first argument. The second

	 * argument is the relocated address of the page table to use instead

	 * of the page table in trampoline memory (if required).

	 */

	movq	%r15, %rdi

	leaq	rva(top_pgtable)(%rbx), %rsi

	call	configure_5level_paging



	/*

	 * cleanup_trampoline() would restore trampoline memory.

	 *

	 * RDI is address of the page table to use instead of page table

	 * in trampoline memory (if required).

	 */

	leaq	rva(top_pgtable)(%rbx), %rdi

	call	cleanup_trampoline



	/* Zero EFLAGS */

	pushq	$0

	popfq

arch/x86/boot/compressed/pgtable_64.c

+4 −14
Original line number Diff line number Diff line
@@ -101,7 +101,7 @@ static unsigned long find_trampoline_placement(void) 
	return bios_start - TRAMPOLINE_32BIT_SIZE;

}



asmlinkage void configure_5level_paging(struct boot_params *bp)

asmlinkage void configure_5level_paging(struct boot_params *bp, void *pgtable)

{

	void (*toggle_la57)(void *cr3);

	bool l5_required = false;
@@ -191,22 +191,12 @@ asmlinkage void configure_5level_paging(struct boot_params *bp) 
	}



	toggle_la57(trampoline_32bit);

}



void cleanup_trampoline(void *pgtable)

{

	void *trampoline_pgtable;



	trampoline_pgtable = trampoline_32bit;



	/*

	 * Move the top level page table out of trampoline memory,

	 * if it's there.

	 * Move the top level page table out of trampoline memory.

	 */

	if ((void *)__native_read_cr3() == trampoline_pgtable) {

		memcpy(pgtable, trampoline_pgtable, PAGE_SIZE);

	memcpy(pgtable, trampoline_32bit, PAGE_SIZE);

	native_write_cr3((unsigned long)pgtable);

	}



	/* Restore trampoline memory */

	memcpy(trampoline_32bit, trampoline_save, TRAMPOLINE_32BIT_SIZE);