LoongArch: Add vector extensions support

Add LoongArch's vector extensions support, which including 128bit LSX
(i.e., Loongson SIMD eXtension) and 256bit LASX (i.e., Loongson Advanced
SIMD eXtension).

Linux kernel doesn't use vector itself, it only handle exceptions and
context save/restore. So it only needs a subset of these instructions:

* Vector load/store:   vld vst vldx vstx xvld xvst xvldx xvstx
* 8bit-elements move:  vpickve2gr.b xvpickve2gr.b vinsgr2vr.b xvinsgr2vr.b
* 16bit-elements move: vpickve2gr.h xvpickve2gr.h vinsgr2vr.h xvinsgr2vr.h
* 32bit-elements move: vpickve2gr.w xvpickve2gr.w vinsgr2vr.w xvinsgr2vr.w
* 64bit-elements move: vpickve2gr.d xvpickve2gr.d vinsgr2vr.d xvinsgr2vr.d
* Elements permute:    vpermi.w vpermi.d xvpermi.w xvpermi.d xvpermi.q

Introduce AS_HAS_LSX_EXTENSION and AS_HAS_LASX_EXTENSION to avoid non-
vector toolchains complains unsupported instructions.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 182 insertions, 3 deletions

diff --git a/arch/loongarch/include/asm/fpu.h b/arch/loongarch/include/asm/fpu.h
index 192f8e35d912..e4193d637f66 100644
--- a/arch/loongarch/include/asm/fpu.h
+++ b/arch/loongarch/include/asm/fpu.h
@@ -28,6 +28,26 @@ extern void _init_fpu(unsigned int);
 extern void _save_fp(struct loongarch_fpu *);
 extern void _restore_fp(struct loongarch_fpu *);
 
+extern void _save_lsx(struct loongarch_fpu *fpu);
+extern void _restore_lsx(struct loongarch_fpu *fpu);
+extern void _init_lsx_upper(void);
+extern void _restore_lsx_upper(struct loongarch_fpu *fpu);
+
+extern void _save_lasx(struct loongarch_fpu *fpu);
+extern void _restore_lasx(struct loongarch_fpu *fpu);
+extern void _init_lasx_upper(void);
+extern void _restore_lasx_upper(struct loongarch_fpu *fpu);
+
+static inline void enable_lsx(void);
+static inline void disable_lsx(void);
+static inline void save_lsx(struct task_struct *t);
+static inline void restore_lsx(struct task_struct *t);
+
+static inline void enable_lasx(void);
+static inline void disable_lasx(void);
+static inline void save_lasx(struct task_struct *t);
+static inline void restore_lasx(struct task_struct *t);
+
 /*
  * Mask the FCSR Cause bits according to the Enable bits, observing
  * that Unimplemented is always enabled.
@@ -44,6 +64,29 @@ static inline int is_fp_enabled(void)
 		1 : 0;
 }
 
+static inline int is_lsx_enabled(void)
+{
+	if (!cpu_has_lsx)
+		return 0;
+
+	return (csr_read32(LOONGARCH_CSR_EUEN) & CSR_EUEN_LSXEN) ?
+		1 : 0;
+}
+
+static inline int is_lasx_enabled(void)
+{
+	if (!cpu_has_lasx)
+		return 0;
+
+	return (csr_read32(LOONGARCH_CSR_EUEN) & CSR_EUEN_LASXEN) ?
+		1 : 0;
+}
+
+static inline int is_simd_enabled(void)
+{
+	return is_lsx_enabled() | is_lasx_enabled();
+}
+
 #define enable_fpu()		set_csr_euen(CSR_EUEN_FPEN)
 
 #define disable_fpu()		clear_csr_euen(CSR_EUEN_FPEN)
@@ -81,9 +124,22 @@ static inline void own_fpu(int restore)
 static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
 {
 	if (is_fpu_owner()) {
-		if (save)
-			_save_fp(&tsk->thread.fpu);
-		disable_fpu();
+		if (!is_simd_enabled()) {
+			if (save)
+				_save_fp(&tsk->thread.fpu);
+			disable_fpu();
+		} else {
+			if (save) {
+				if (!is_lasx_enabled())
+					save_lsx(tsk);
+				else
+					save_lasx(tsk);
+			}
+			disable_fpu();
+			disable_lsx();
+			disable_lasx();
+			clear_tsk_thread_flag(tsk, TIF_USEDSIMD);
+		}
 		clear_tsk_thread_flag(tsk, TIF_USEDFPU);
 	}
 	KSTK_EUEN(tsk) &= ~(CSR_EUEN_FPEN | CSR_EUEN_LSXEN | CSR_EUEN_LASXEN);
@@ -129,4 +185,127 @@ static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
 	return tsk->thread.fpu.fpr;
 }
 
+static inline int is_simd_owner(void)
+{
+	return test_thread_flag(TIF_USEDSIMD);
+}
+
+#ifdef CONFIG_CPU_HAS_LSX
+
+static inline void enable_lsx(void)
+{
+	if (cpu_has_lsx)
+		csr_xchg32(CSR_EUEN_LSXEN, CSR_EUEN_LSXEN, LOONGARCH_CSR_EUEN);
+}
+
+static inline void disable_lsx(void)
+{
+	if (cpu_has_lsx)
+		csr_xchg32(0, CSR_EUEN_LSXEN, LOONGARCH_CSR_EUEN);
+}
+
+static inline void save_lsx(struct task_struct *t)
+{
+	if (cpu_has_lsx)
+		_save_lsx(&t->thread.fpu);
+}
+
+static inline void restore_lsx(struct task_struct *t)
+{
+	if (cpu_has_lsx)
+		_restore_lsx(&t->thread.fpu);
+}
+
+static inline void init_lsx_upper(void)
+{
+	/*
+	 * Check cpu_has_lsx only if it's a constant. This will allow the
+	 * compiler to optimise out code for CPUs without LSX without adding
+	 * an extra redundant check for CPUs with LSX.
+	 */
+	if (__builtin_constant_p(cpu_has_lsx) && !cpu_has_lsx)
+		return;
+
+	_init_lsx_upper();
+}
+
+static inline void restore_lsx_upper(struct task_struct *t)
+{
+	if (cpu_has_lsx)
+		_restore_lsx_upper(&t->thread.fpu);
+}
+
+#else
+static inline void enable_lsx(void) {}
+static inline void disable_lsx(void) {}
+static inline void save_lsx(struct task_struct *t) {}
+static inline void restore_lsx(struct task_struct *t) {}
+static inline void init_lsx_upper(void) {}
+static inline void restore_lsx_upper(struct task_struct *t) {}
+#endif
+
+#ifdef CONFIG_CPU_HAS_LASX
+
+static inline void enable_lasx(void)
+{
+
+	if (cpu_has_lasx)
+		csr_xchg32(CSR_EUEN_LASXEN, CSR_EUEN_LASXEN, LOONGARCH_CSR_EUEN);
+}
+
+static inline void disable_lasx(void)
+{
+	if (cpu_has_lasx)
+		csr_xchg32(0, CSR_EUEN_LASXEN, LOONGARCH_CSR_EUEN);
+}
+
+static inline void save_lasx(struct task_struct *t)
+{
+	if (cpu_has_lasx)
+		_save_lasx(&t->thread.fpu);
+}
+
+static inline void restore_lasx(struct task_struct *t)
+{
+	if (cpu_has_lasx)
+		_restore_lasx(&t->thread.fpu);
+}
+
+static inline void init_lasx_upper(void)
+{
+	if (cpu_has_lasx)
+		_init_lasx_upper();
+}
+
+static inline void restore_lasx_upper(struct task_struct *t)
+{
+	if (cpu_has_lasx)
+		_restore_lasx_upper(&t->thread.fpu);
+}
+
+#else
+static inline void enable_lasx(void) {}
+static inline void disable_lasx(void) {}
+static inline void save_lasx(struct task_struct *t) {}
+static inline void restore_lasx(struct task_struct *t) {}
+static inline void init_lasx_upper(void) {}
+static inline void restore_lasx_upper(struct task_struct *t) {}
+#endif
+
+static inline int thread_lsx_context_live(void)
+{
+	if (__builtin_constant_p(cpu_has_lsx) && !cpu_has_lsx)
+		return 0;
+
+	return test_thread_flag(TIF_LSX_CTX_LIVE);
+}
+
+static inline int thread_lasx_context_live(void)
+{
+	if (__builtin_constant_p(cpu_has_lasx) && !cpu_has_lasx)
+		return 0;
+
+	return test_thread_flag(TIF_LASX_CTX_LIVE);
+}
+
 #endif /* _ASM_FPU_H */