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LoongArch: Skip relocation-time KASLR if already applied

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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: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: WANG Rui <wangrui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
WANG Rui 2026-05-21 20:58:36 +08:00 committed by Huacai Chen
parent 03d8273542
commit 08ade00fbb
1 changed files with 12 additions and 0 deletions
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12
arch/loongarch/kernel/relocate.c
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@ -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");