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, 110 insertions, 0 deletions

diff --git a/arch/loongarch/kernel/ptrace.c b/arch/loongarch/kernel/ptrace.c
index 5fcffb452367..a0767c3a0f0a 100644
--- a/arch/loongarch/kernel/ptrace.c
+++ b/arch/loongarch/kernel/ptrace.c
@@ -250,6 +250,90 @@ static int cfg_set(struct task_struct *target,
 	return 0;
 }
 
+#ifdef CONFIG_CPU_HAS_LSX
+
+static void copy_pad_fprs(struct task_struct *target,
+			 const struct user_regset *regset,
+			 struct membuf *to, unsigned int live_sz)
+{
+	int i, j;
+	unsigned long long fill = ~0ull;
+	unsigned int cp_sz, pad_sz;
+
+	cp_sz = min(regset->size, live_sz);
+	pad_sz = regset->size - cp_sz;
+	WARN_ON(pad_sz % sizeof(fill));
+
+	for (i = 0; i < NUM_FPU_REGS; i++) {
+		membuf_write(to, &target->thread.fpu.fpr[i], cp_sz);
+		for (j = 0; j < (pad_sz / sizeof(fill)); j++) {
+			membuf_store(to, fill);
+		}
+	}
+}
+
+static int simd_get(struct task_struct *target,
+		    const struct user_regset *regset,
+		    struct membuf to)
+{
+	const unsigned int wr_size = NUM_FPU_REGS * regset->size;
+
+	if (!tsk_used_math(target)) {
+		/* The task hasn't used FP or LSX, fill with 0xff */
+		copy_pad_fprs(target, regset, &to, 0);
+	} else if (!test_tsk_thread_flag(target, TIF_LSX_CTX_LIVE)) {
+		/* Copy scalar FP context, fill the rest with 0xff */
+		copy_pad_fprs(target, regset, &to, 8);
+#ifdef CONFIG_CPU_HAS_LASX
+	} else if (!test_tsk_thread_flag(target, TIF_LASX_CTX_LIVE)) {
+		/* Copy LSX 128 Bit context, fill the rest with 0xff */
+		copy_pad_fprs(target, regset, &to, 16);
+#endif
+	} else if (sizeof(target->thread.fpu.fpr[0]) == regset->size) {
+		/* Trivially copy the vector registers */
+		membuf_write(&to, &target->thread.fpu.fpr, wr_size);
+	} else {
+		/* Copy as much context as possible, fill the rest with 0xff */
+		copy_pad_fprs(target, regset, &to, sizeof(target->thread.fpu.fpr[0]));
+	}
+
+	return 0;
+}
+
+static int simd_set(struct task_struct *target,
+		    const struct user_regset *regset,
+		    unsigned int pos, unsigned int count,
+		    const void *kbuf, const void __user *ubuf)
+{
+	const unsigned int wr_size = NUM_FPU_REGS * regset->size;
+	unsigned int cp_sz;
+	int i, err, start;
+
+	init_fp_ctx(target);
+
+	if (sizeof(target->thread.fpu.fpr[0]) == regset->size) {
+		/* Trivially copy the vector registers */
+		err = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+					 &target->thread.fpu.fpr,
+					 0, wr_size);
+	} else {
+		/* Copy as much context as possible */
+		cp_sz = min_t(unsigned int, regset->size,
+			      sizeof(target->thread.fpu.fpr[0]));
+
+		i = start = err = 0;
+		for (; i < NUM_FPU_REGS; i++, start += regset->size) {
+			err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+						  &target->thread.fpu.fpr[i],
+						  start, start + cp_sz);
+		}
+	}
+
+	return err;
+}
+
+#endif /* CONFIG_CPU_HAS_LSX */
+
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 
 /*
@@ -708,6 +792,12 @@ enum loongarch_regset {
 	REGSET_GPR,
 	REGSET_FPR,
 	REGSET_CPUCFG,
+#ifdef CONFIG_CPU_HAS_LSX
+	REGSET_LSX,
+#endif
+#ifdef CONFIG_CPU_HAS_LASX
+	REGSET_LASX,
+#endif
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 	REGSET_HW_BREAK,
 	REGSET_HW_WATCH,
@@ -739,6 +829,26 @@ static const struct user_regset loongarch64_regsets[] = {
 		.regset_get	= cfg_get,
 		.set		= cfg_set,
 	},
+#ifdef CONFIG_CPU_HAS_LSX
+	[REGSET_LSX] = {
+		.core_note_type	= NT_LOONGARCH_LSX,
+		.n		= NUM_FPU_REGS,
+		.size		= 16,
+		.align		= 16,
+		.regset_get	= simd_get,
+		.set		= simd_set,
+	},
+#endif
+#ifdef CONFIG_CPU_HAS_LASX
+	[REGSET_LASX] = {
+		.core_note_type	= NT_LOONGARCH_LASX,
+		.n		= NUM_FPU_REGS,
+		.size		= 32,
+		.align		= 32,
+		.regset_get	= simd_get,
+		.set		= simd_set,
+	},
+#endif
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 	[REGSET_HW_BREAK] = {
 		.core_note_type = NT_LOONGARCH_HW_BREAK,