This is needed to support recent hardware in the amdgpu DRM driver. The
FPU code in that driver is not performance-critical, so only provide the
minimal support.
Signed-off-by: Samuel Holland <samuel.holland@xxxxxxxxxx>
---
arch/riscv/include/asm/switch_to.h | 14 ++++++++++++++
arch/riscv/kernel/process.c | 3 +++
2 files changed, 17 insertions(+)
diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h
index f90d8e42f3c7..4b15f1292fc4 100644
--- a/arch/riscv/include/asm/switch_to.h
+++ b/arch/riscv/include/asm/switch_to.h
@@ -63,6 +63,20 @@ static __always_inline bool has_fpu(void)
return riscv_has_extension_likely(RISCV_ISA_EXT_f) ||
riscv_has_extension_likely(RISCV_ISA_EXT_d);
}
+
+static inline void kernel_fpu_begin(void)
+{
+ preempt_disable();
+ fstate_save(current, task_pt_regs(current));
+ csr_set(CSR_SSTATUS, SR_FS);
+}
+
+static inline void kernel_fpu_end(void)
+{
+ csr_clear(CSR_SSTATUS, SR_FS);
+ fstate_restore(current, task_pt_regs(current));
+ preempt_enable();
+}
#else
static __always_inline bool has_fpu(void) { return false; }
#define fstate_save(task, regs) do { } while (0)
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 4f21d970a129..6a18bc709d1c 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -225,3 +225,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
p->thread.sp = (unsigned long)childregs; /* kernel sp */
return 0;
}
+
+EXPORT_SYMBOL_GPL(__fstate_save);
+EXPORT_SYMBOL_GPL(__fstate_restore);
--
2.42.0
