[-next,v17,07/20] riscv: Introduce riscv_v_vsize to record size of Vector context

Commit Message

Andy Chiu March 27, 2023, 4:49 p.m. UTC

From: Greentime Hu <[e-mail]>

This patch is used to detect the size of CPU vector registers and use
riscv_v_vsize to save the size of all the vector registers. It assumes all
harts has the same capabilities in a SMP system.

Co-developed-by: Guo Ren <[e-mail]>
Signed-off-by: Guo Ren <[e-mail]>
Co-developed-by: Vincent Chen <[e-mail]>
Signed-off-by: Vincent Chen <[e-mail]>
Signed-off-by: Greentime Hu <[e-mail]>
Signed-off-by: Andy Chiu <[e-mail]>
Reviewed-by: Conor Dooley <[e-mail]>
---
 arch/riscv/include/asm/vector.h |  5 +++++
 arch/riscv/kernel/Makefile      |  1 +
 arch/riscv/kernel/cpufeature.c  |  2 ++
 arch/riscv/kernel/vector.c      | 20 ++++++++++++++++++++
 4 files changed, 28 insertions(+)
 create mode 100644 arch/riscv/kernel/vector.c

Comments

Heiko Stuebner March 31, 2023, 11:02 a.m. UTC | #1

Am Montag, 27. März 2023, 18:49:27 CEST schrieb Andy Chiu:
> From: Greentime Hu <[e-mail]>
> 
> This patch is used to detect the size of CPU vector registers and use
> riscv_v_vsize to save the size of all the vector registers. 

> It assumes all
> harts has the same capabilities in a SMP system.

is this mandated somewhere?

Because for most other things we seem to want to check that this is
actually true.

So somehow I'd expect the kernel to at least check the VLEN on each
hart and loudly complain if those do not match?

> Co-developed-by: Guo Ren <[e-mail]>
> Signed-off-by: Guo Ren <[e-mail]>
> Co-developed-by: Vincent Chen <[e-mail]>
> Signed-off-by: Vincent Chen <[e-mail]>
> Signed-off-by: Greentime Hu <[e-mail]>
> Signed-off-by: Andy Chiu <[e-mail]>
> Reviewed-by: Conor Dooley <[e-mail]>

Tested-by: Heiko Stuebner <[e-mail]>


Heiko

Patch

diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h
index dfe5a321b2b4..e433ba3cd4da 100644
--- a/arch/riscv/include/asm/vector.h
+++ b/arch/riscv/include/asm/vector.h
@@ -13,6 +13,9 @@ 
 #include <asm/hwcap.h>
 #include <asm/csr.h>
 
+extern unsigned long riscv_v_vsize;
+void riscv_v_setup_vsize(void);
+
 static __always_inline bool has_vector(void)
 {
 	return riscv_has_extension_likely(RISCV_ISA_EXT_v);
@@ -31,6 +34,8 @@  static __always_inline void riscv_v_disable(void)
 #else /* ! CONFIG_RISCV_ISA_V  */
 
 static __always_inline bool has_vector(void) { return false; }
+#define riscv_v_vsize (0)
+#define riscv_v_setup_vsize()			do {} while (0)
 
 #endif /* CONFIG_RISCV_ISA_V */
 
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 392fa6e35d4a..be23a021ec32 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -55,6 +55,7 @@  obj-$(CONFIG_MMU) += vdso.o vdso/
 
 obj-$(CONFIG_RISCV_M_MODE)	+= traps_misaligned.o
 obj-$(CONFIG_FPU)		+= fpu.o
+obj-$(CONFIG_RISCV_ISA_V)	+= vector.o
 obj-$(CONFIG_SMP)		+= smpboot.o
 obj-$(CONFIG_SMP)		+= smp.o
 obj-$(CONFIG_SMP)		+= cpu_ops.o
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 923ca75f2192..267070f3cc9e 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -17,6 +17,7 @@ 
 #include <asm/hwcap.h>
 #include <asm/patch.h>
 #include <asm/processor.h>
+#include <asm/vector.h>
 
 #define NUM_ALPHA_EXTS ('z' - 'a' + 1)
 
@@ -263,6 +264,7 @@  void __init riscv_fill_hwcap(void)
 	}
 
 	if (elf_hwcap & COMPAT_HWCAP_ISA_V) {
+		riscv_v_setup_vsize();
 		/*
 		 * ISA string in device tree might have 'v' flag, but
 		 * CONFIG_RISCV_ISA_V is disabled in kernel.
diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c
new file mode 100644
index 000000000000..03582e2ade83
--- /dev/null
+++ b/arch/riscv/kernel/vector.c
@@ -0,0 +1,20 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2023 SiFive
+ * Author: Andy Chiu <[e-mail]>
+ */
+#include <linux/export.h>
+
+#include <asm/vector.h>
+#include <asm/csr.h>
+
+unsigned long riscv_v_vsize __read_mostly;
+EXPORT_SYMBOL_GPL(riscv_v_vsize);
+
+void riscv_v_setup_vsize(void)
+{
+	/* There are 32 vector registers with vlenb length. */
+	riscv_v_enable();
+	riscv_v_vsize = csr_read(CSR_VLENB) * 32;
+	riscv_v_disable();
+}