This adds the SIMD stash/unstash operations that we need to allow UEFI
runtime services calls to call back into the kernel.
The UEFI bindings for arm64 stipulate that the ordinary AAPCS rules apply,
which means that code may use FP/NEON registers, and may also expect that
the values of the callee saved registers q8 - q15 are preserved across
function calls.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
arch/arm64/include/asm/efi.h | 33 ++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index a9e54aad15ef..d6bbbcba9820 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -81,4 +81,37 @@ static inline void efi_set_pgd(struct mm_struct *mm)
void efi_virtmap_load(void);
void efi_virtmap_unload(void);
+struct efi_simd_reg_stash {
+ u8 q8[16];
+ u8 q9[16];
+ u8 q10[16];
+ u8 q11[16];
+ u8 q12[16];
+ u8 q13[16];
+ u8 q14[16];
+ u8 q15[16];
+};
+
+static inline void arch_efi_stash_simd_regs(struct efi_simd_reg_stash *stash)
+{
+ asm( "stp q8, q9, [%1];"
+ "stp q10, q11, [%1, #32];"
+ "stp q12, q13, [%1, #64];"
+ "stp q14, q15, [%1, #96];"
+
+ : "=m"(*stash)
+ : "r"(stash));
+}
+
+static inline void arch_efi_unstash_simd_regs(struct efi_simd_reg_stash *stash)
+{
+ asm( "ldp q8, q9, [%1];"
+ "ldp q10, q11, [%1, #32];"
+ "ldp q12, q13, [%1, #64];"
+ "ldp q14, q15, [%1, #96];"
+
+ :
+ : "m"(*stash), "r"(stash));
+}
+
#endif /* _ASM_EFI_H */
--
2.7.4
--
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