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| author | Mark Brown <broonie@kernel.org> | 2022-04-19 13:22:23 +0200 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2022-04-22 19:51:02 +0200 |
| commit | 0033cd9339642f9b7bef23f96aa2e7277ab51cce (patch) | |
| tree | f5c437cd6e6c4cd3f0f5a8d7c0e690d5b358f6a2 /arch/arm64/kernel/entry-fpsimd.S | |
| parent | arm64/sme: Implement streaming SVE context switching (diff) | |
| download | linux-0033cd9339642f9b7bef23f96aa2e7277ab51cce.tar.xz linux-0033cd9339642f9b7bef23f96aa2e7277ab51cce.zip | |
arm64/sme: Implement ZA context switching
Allocate space for storing ZA on first access to SME and use that to save
and restore ZA state when context switching. We do this by using the vector
form of the LDR and STR ZA instructions, these do not require streaming
mode and have implementation recommendations that they avoid contention
issues in shared SMCU implementations.
Since ZA is architecturally guaranteed to be zeroed when enabled we do not
need to explicitly zero ZA, either we will be restoring from a saved copy
or trapping on first use of SME so we know that ZA must be disabled.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220419112247.711548-16-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/entry-fpsimd.S')
| -rw-r--r-- | arch/arm64/kernel/entry-fpsimd.S | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/arch/arm64/kernel/entry-fpsimd.S b/arch/arm64/kernel/entry-fpsimd.S index 6f88c0f86d50..229436f33df5 100644 --- a/arch/arm64/kernel/entry-fpsimd.S +++ b/arch/arm64/kernel/entry-fpsimd.S @@ -99,4 +99,26 @@ SYM_FUNC_START(sme_set_vq) ret SYM_FUNC_END(sme_set_vq) +/* + * Save the SME state + * + * x0 - pointer to buffer for state + */ +SYM_FUNC_START(za_save_state) + _sme_rdsvl 1, 1 // x1 = VL/8 + sme_save_za 0, x1, 12 + ret +SYM_FUNC_END(za_save_state) + +/* + * Load the SME state + * + * x0 - pointer to buffer for state + */ +SYM_FUNC_START(za_load_state) + _sme_rdsvl 1, 1 // x1 = VL/8 + sme_load_za 0, x1, 12 + ret +SYM_FUNC_END(za_load_state) + #endif /* CONFIG_ARM64_SME */ |