diff options
| author | Yeoreum Yun <yeoreum.yun@arm.com> | 2026-03-14 17:51:31 +0000 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2026-03-27 17:29:10 +0000 |
| commit | e223258ed8a683d9debbb03ca1be0736f2c12e5b (patch) | |
| tree | 9b1cc036711ba9e9ba55709323818782c935a86b | |
| parent | 377609ae8b6ac2ef522c9dcecfa20a7123116dbf (diff) | |
arm64: armv8_deprecated: Disable swp emulation when FEAT_LSUI present
The purpose of supporting LSUI is to eliminate PAN toggling. CPUs that
support LSUI are unlikely to support a 32-bit runtime. Rather than
emulating the SWP instruction using LSUI instructions in order to remove
PAN toggling, simply disable SWP emulation.
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
[catalin.marinas@arm.com: some tweaks to the in-code comment]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
| -rw-r--r-- | arch/arm64/kernel/armv8_deprecated.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c index e737c6295ec7..b7a1f8b788bb 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c @@ -610,6 +610,20 @@ static int __init armv8_deprecated_init(void) } #endif + +#ifdef CONFIG_SWP_EMULATION + /* + * The purpose of supporting LSUI is to eliminate PAN toggling. CPUs + * that support LSUI are unlikely to support a 32-bit runtime. Rather + * than emulating the SWP instruction using LSUI instructions, simply + * disable SWP emulation. + */ + if (cpus_have_final_cap(ARM64_HAS_LSUI)) { + insn_swp.status = INSN_UNAVAILABLE; + pr_info("swp/swpb instruction emulation is not supported on this system\n"); + } +#endif + for (int i = 0; i < ARRAY_SIZE(insn_emulations); i++) { struct insn_emulation *ie = insn_emulations[i]; |