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Message-Id: <20240510-zve-detection-v5-7-0711bdd26c12@sifive.com>
Date: Fri, 10 May 2024 00:26:57 +0800
From: Andy Chiu <andy.chiu@...ive.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
Conor Dooley <conor.dooley@...rochip.com>, Heiko Stuebner <heiko@...ech.de>,
Andy Chiu <andy.chiu@...ive.com>, Guo Ren <guoren@...nel.org>,
Conor Dooley <conor@...nel.org>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Jonathan Corbet <corbet@....net>, Evan Green <evan@...osinc.com>,
Clément Léger <cleger@...osinc.com>,
Shuah Khan <shuah@...nel.org>
Cc: linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
Palmer Dabbelt <palmer@...osinc.com>,
Vincent Chen <vincent.chen@...ive.com>,
Greentime Hu <greentime.hu@...ive.com>, devicetree@...r.kernel.org,
linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org,
Joel Granados <j.granados@...sung.com>
Subject: [PATCH v5 7/8] riscv: vector: adjust minimum Vector requirement to
ZVE32X
Make has_vector() to check for ZVE32X. Every in-kernel usage of V that
requires a more complicate version of V must then call out explicitly.
Also, change riscv_v_first_use_handler(), and boot code that calls
riscv_v_setup_vsize() to accept ZVE32X.
Most kernel/user interfaces requires minimum of ZVE32X. Thus, programs
compiled and run with ZVE32X should be supported by the kernel on most
aspects. This includes context-switch, signal, ptrace, prctl, and
hwprobe.
One exception is that ELF_HWCAP returns 'V' only if full V is supported
on the platform. This means that the system without a full V must not
rely on ELF_HWCAP to tell whether it is allowable to execute Vector
without first invoking a prctl() check.
Signed-off-by: Andy Chiu <andy.chiu@...ive.com>
Acked-by: Joel Granados <j.granados@...sung.com>
---
Changelog v5:
- Remove the paramerter from has_vector()'s prototype. Instead, make it
check for ZVE32X only. Everything else should make additional
alternative checks. (Conor)
Changelog v4:
- check static_assert for !CONFIG_RISCV_ISA_V case in has_vector.
Changelog v2:
- update the comment in hwprobe.
---
arch/riscv/include/asm/vector.h | 10 +++++-----
arch/riscv/kernel/cpufeature.c | 5 ++++-
arch/riscv/kernel/sys_hwprobe.c | 6 +++++-
arch/riscv/kernel/vector.c | 5 ++++-
arch/riscv/lib/uaccess.S | 2 +-
5 files changed, 19 insertions(+), 9 deletions(-)
diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h
index 731dcd0ed4de..be7d309cca8a 100644
--- a/arch/riscv/include/asm/vector.h
+++ b/arch/riscv/include/asm/vector.h
@@ -37,7 +37,7 @@ static inline u32 riscv_v_flags(void)
static __always_inline bool has_vector(void)
{
- return riscv_has_extension_unlikely(RISCV_ISA_EXT_v);
+ return riscv_has_extension_unlikely(RISCV_ISA_EXT_ZVE32X);
}
static inline void __riscv_v_vstate_clean(struct pt_regs *regs)
@@ -91,7 +91,7 @@ static __always_inline void __vstate_csr_restore(struct __riscv_v_ext_state *src
{
asm volatile (
".option push\n\t"
- ".option arch, +v\n\t"
+ ".option arch, +zve32x\n\t"
"vsetvl x0, %2, %1\n\t"
".option pop\n\t"
"csrw " __stringify(CSR_VSTART) ", %0\n\t"
@@ -109,7 +109,7 @@ static inline void __riscv_v_vstate_save(struct __riscv_v_ext_state *save_to,
__vstate_csr_save(save_to);
asm volatile (
".option push\n\t"
- ".option arch, +v\n\t"
+ ".option arch, +zve32x\n\t"
"vsetvli %0, x0, e8, m8, ta, ma\n\t"
"vse8.v v0, (%1)\n\t"
"add %1, %1, %0\n\t"
@@ -131,7 +131,7 @@ static inline void __riscv_v_vstate_restore(struct __riscv_v_ext_state *restore_
riscv_v_enable();
asm volatile (
".option push\n\t"
- ".option arch, +v\n\t"
+ ".option arch, +zve32x\n\t"
"vsetvli %0, x0, e8, m8, ta, ma\n\t"
"vle8.v v0, (%1)\n\t"
"add %1, %1, %0\n\t"
@@ -153,7 +153,7 @@ static inline void __riscv_v_vstate_discard(void)
riscv_v_enable();
asm volatile (
".option push\n\t"
- ".option arch, +v\n\t"
+ ".option arch, +zve32x\n\t"
"vsetvli %0, x0, e8, m8, ta, ma\n\t"
"vmv.v.i v0, -1\n\t"
"vmv.v.i v8, -1\n\t"
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index ad3e613ee30f..53be3365e302 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -720,11 +720,14 @@ void __init riscv_fill_hwcap(void)
elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
}
- if (elf_hwcap & COMPAT_HWCAP_ISA_V) {
+ if (__riscv_isa_extension_available(NULL, RISCV_ISA_EXT_ZVE32X)) {
/*
* This cannot fail when called on the boot hart
*/
riscv_v_setup_vsize();
+ }
+
+ if (elf_hwcap & COMPAT_HWCAP_ISA_V) {
/*
* ISA string in device tree might have 'v' flag, but
* CONFIG_RISCV_ISA_V is disabled in kernel.
diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
index 35390b4a5a17..83fcc939df67 100644
--- a/arch/riscv/kernel/sys_hwprobe.c
+++ b/arch/riscv/kernel/sys_hwprobe.c
@@ -69,7 +69,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
if (riscv_isa_extension_available(NULL, c))
pair->value |= RISCV_HWPROBE_IMA_C;
- if (has_vector())
+ if (has_vector() && riscv_isa_extension_available(NULL, v))
pair->value |= RISCV_HWPROBE_IMA_V;
/*
@@ -113,6 +113,10 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
EXT_KEY(ZICOND);
EXT_KEY(ZIHINTPAUSE);
+ /*
+ * All the following extensions must depend on the kernel
+ * support of V.
+ */
if (has_vector()) {
EXT_KEY(ZVE32X);
EXT_KEY(ZVE32F);
diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c
index 6727d1d3b8f2..682b3feee451 100644
--- a/arch/riscv/kernel/vector.c
+++ b/arch/riscv/kernel/vector.c
@@ -173,8 +173,11 @@ bool riscv_v_first_use_handler(struct pt_regs *regs)
u32 __user *epc = (u32 __user *)regs->epc;
u32 insn = (u32)regs->badaddr;
+ if (!has_vector())
+ return false;
+
/* Do not handle if V is not supported, or disabled */
- if (!(ELF_HWCAP & COMPAT_HWCAP_ISA_V))
+ if (!riscv_v_vstate_ctrl_user_allowed())
return false;
/* If V has been enabled then it is not the first-use trap */
diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S
index bc22c078aba8..bbe143bb32a0 100644
--- a/arch/riscv/lib/uaccess.S
+++ b/arch/riscv/lib/uaccess.S
@@ -14,7 +14,7 @@
SYM_FUNC_START(__asm_copy_to_user)
#ifdef CONFIG_RISCV_ISA_V
- ALTERNATIVE("j fallback_scalar_usercopy", "nop", 0, RISCV_ISA_EXT_v, CONFIG_RISCV_ISA_V)
+ ALTERNATIVE("j fallback_scalar_usercopy", "nop", 0, RISCV_ISA_EXT_ZVE32X, CONFIG_RISCV_ISA_V)
REG_L t0, riscv_v_usercopy_threshold
bltu a2, t0, fallback_scalar_usercopy
tail enter_vector_usercopy
--
2.44.0.rc2
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