Commit 08ade00f authored by WANG Rui's avatar WANG Rui Committed by Huacai Chen
Browse files

LoongArch: Skip relocation-time KASLR if already applied 



When the kernel is relocated during early boot (efistub or kexec_file),
a randomized load address may has already been selected and applied. In
this case, performing KASLR again in relocate.c is unnecessary.

Note: strictly-defined KASLR means the kernel's final runtime address
has a random offset from the kernel's load address, which is implemented
in relocate.c; broadly-defined KALSR means the kernel's final runtime
address has a random offset from the kernel's link address (a.k.a.
VMLINUX_LOAD_ADDRESS), which also include the efistlub implementation,
kexec_file implementation and QEMU direct kernel boot. kaslr_disabled()
return true only means strictly-defined KASLR is disabled.

Acked-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarWANG Rui <wangrui@loongson.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent 03d82735

arch/loongarch/kernel/relocate.c

+12 −0
Original line number Diff line number Diff line
@@ -134,11 +134,23 @@ early_param("nokaslr", nokaslr); 


#define KASLR_DISABLED_MESSAGE "KASLR is disabled by %s in %s cmdline.\n"



/*

 * Note: strictly-defined KASLR means the kernel's final runtime address

 * has a random offset from the kernel's load address, which is implemented

 * in relocate.c; broadly-defined KALSR means the kernel's final runtime

 * address has a random offset from the kernel's link address (a.k.a.

 * VMLINUX_LOAD_ADDRESS), which also include the efistlub implementation,

 * kexec_file implementation and QEMU direct kernel boot. kaslr_disabled()

 * return true only means strictly-defined KASLR is disabled.

 */

static inline __init bool kaslr_disabled(void)

{

	char *str;

	const char *builtin_cmdline = CONFIG_CMDLINE;



	if (kaslr_offset())

		return true; /* KASLR is performed during early boot. */



	str = strstr(builtin_cmdline, "nokaslr");

	if (str == builtin_cmdline || (str > builtin_cmdline && *(str - 1) == ' ')) {

		pr_info(KASLR_DISABLED_MESSAGE, "\'nokaslr\'", "built-in");