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, 80 insertions, 4 deletions

diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
index e73d9bbe1658..e56df45f7202 100644
--- a/arch/loongarch/kernel/traps.c
+++ b/arch/loongarch/kernel/traps.c
@@ -852,12 +852,67 @@ static void init_restore_fp(void)
 	BUG_ON(!is_fp_enabled());
 }
 
+static void init_restore_lsx(void)
+{
+	enable_lsx();
+
+	if (!thread_lsx_context_live()) {
+		/* First time LSX context user */
+		init_restore_fp();
+		init_lsx_upper();
+		set_thread_flag(TIF_LSX_CTX_LIVE);
+	} else {
+		if (!is_simd_owner()) {
+			if (is_fpu_owner()) {
+				restore_lsx_upper(current);
+			} else {
+				__own_fpu();
+				restore_lsx(current);
+			}
+		}
+	}
+
+	set_thread_flag(TIF_USEDSIMD);
+
+	BUG_ON(!is_fp_enabled());
+	BUG_ON(!is_lsx_enabled());
+}
+
+static void init_restore_lasx(void)
+{
+	enable_lasx();
+
+	if (!thread_lasx_context_live()) {
+		/* First time LASX context user */
+		init_restore_lsx();
+		init_lasx_upper();
+		set_thread_flag(TIF_LASX_CTX_LIVE);
+	} else {
+		if (is_fpu_owner() || is_simd_owner()) {
+			init_restore_lsx();
+			restore_lasx_upper(current);
+		} else {
+			__own_fpu();
+			enable_lsx();
+			restore_lasx(current);
+		}
+	}
+
+	set_thread_flag(TIF_USEDSIMD);
+
+	BUG_ON(!is_fp_enabled());
+	BUG_ON(!is_lsx_enabled());
+	BUG_ON(!is_lasx_enabled());
+}
+
 asmlinkage void noinstr do_fpu(struct pt_regs *regs)
 {
 	irqentry_state_t state = irqentry_enter(regs);
 
 	local_irq_enable();
 	die_if_kernel("do_fpu invoked from kernel context!", regs);
+	BUG_ON(is_lsx_enabled());
+	BUG_ON(is_lasx_enabled());
 
 	preempt_disable();
 	init_restore_fp();
@@ -872,9 +927,20 @@ asmlinkage void noinstr do_lsx(struct pt_regs *regs)
 	irqentry_state_t state = irqentry_enter(regs);
 
 	local_irq_enable();
-	force_sig(SIGILL);
-	local_irq_disable();
+	if (!cpu_has_lsx) {
+		force_sig(SIGILL);
+		goto out;
+	}
+
+	die_if_kernel("do_lsx invoked from kernel context!", regs);
+	BUG_ON(is_lasx_enabled());
 
+	preempt_disable();
+	init_restore_lsx();
+	preempt_enable();
+
+out:
+	local_irq_disable();
 	irqentry_exit(regs, state);
 }
 
@@ -883,9 +949,19 @@ asmlinkage void noinstr do_lasx(struct pt_regs *regs)
 	irqentry_state_t state = irqentry_enter(regs);
 
 	local_irq_enable();
-	force_sig(SIGILL);
-	local_irq_disable();
+	if (!cpu_has_lasx) {
+		force_sig(SIGILL);
+		goto out;
+	}
+
+	die_if_kernel("do_lasx invoked from kernel context!", regs);
 
+	preempt_disable();
+	init_restore_lasx();
+	preempt_enable();
+
+out:
+	local_irq_disable();
 	irqentry_exit(regs, state);
 }