add basic IPI structure

4 files changed, 83 insertions, 8 deletions

diff --git a/arch/riscv64/kernel/cpu.c b/arch/riscv64/kernel/cpu.c
index d6d07ec..60140e6 100644
--- a/arch/riscv64/kernel/cpu.c
+++ b/arch/riscv64/kernel/cpu.c
@@ -11,6 +11,8 @@
 
 #include <arch/cpu.h>
 
+#include "sbi.h"
+
 /** Keeps track of initialized cpus. */
 static atomic_long cpus = 0;
 
@@ -40,3 +42,35 @@ struct tcb *cur_tcb()
 	register struct tcb *t __asm__ ("tp");
 	return t;
 }
+
+/**
+ * Helper for cpu_send_ipi() to convert linear \p cpu_id to SBI \c
+ * hart_mask_base.
+ *
+ * @param cpu_id CPU id to convert.
+ * @return Corresponding \c hart_mask_base.
+ */
+static long __cpu_offset(id_t cpu_id)
+{
+	return cpu_id / (sizeof(long) * 8);
+}
+
+/**
+ * Helper for cpu_send_ipi() to convert linear \p cpu_id to SBI \c
+ * hart_mask.
+ *
+ * @param cpu_id CPU id to convert.
+ * @param offset Offset from __cpu_offset().
+ * @return Corresponding \c hart_mask.
+ */
+static long __cpu_mask(id_t cpu_id, long offset)
+{
+	return cpu_id - offset * sizeof(long) * 8;
+}
+
+void cpu_send_ipi(id_t cpu_id)
+{
+	long offset = __cpu_offset(cpu_id);
+	long mask = __cpu_mask(cpu_id, offset);
+	sbi_send_ipi(mask, offset);
+}
diff --git a/arch/riscv64/kernel/entry.S b/arch/riscv64/kernel/entry.S
index db662bb..355cd3d 100644
--- a/arch/riscv64/kernel/entry.S
+++ b/arch/riscv64/kernel/entry.S
@@ -77,17 +77,14 @@ _save_context:
 
 handle_exception:
 	li t0, EXC_SYSCALL
-	/* system exceptions fall through, syscalls jump */
+	/* system exceptions fall through, syscalls and ipis jump */
 	/* temp, at some point we want to handle system exceptions as well */
-	beq s4, t0, handle_syscall
+	beq s4, t0, handle_dispatch
 	j	restore_all
 
-handle_syscall:
-	/* add 4 (size of ecall) to EPC to avoid running the same instruction
-	 * twice */
-	csrr    s0, CSR_SEPC
-	addi	s0, s0, 4
+handle_dispatch:
 	/* store execution continuation point */
+	csrr    s0, CSR_SEPC
 	sr	s0, 0(tp)
 	/* allocate space for sys_ret structure on stack and shift argument
 	 * registers down one to make room for the pointer to this structure */
@@ -99,7 +96,8 @@ handle_syscall:
 	mv	a2, a1
 	mv	a1, a0
 	mv	a0, sp
-	jal	syscall_dispatch
+	/* jump to C */
+	jal	dispatch
 	/* move structure from stack into registers. */
 	lr	a0, offsetof_s(sp)
 	lr	a1, offsetof_ar0(sp)
diff --git a/arch/riscv64/kernel/proc.c b/arch/riscv64/kernel/proc.c
index ed8bf93..d2b8dfb 100644
--- a/arch/riscv64/kernel/proc.c
+++ b/arch/riscv64/kernel/proc.c
@@ -8,6 +8,7 @@
 
 #include <apos/tcb.h>
 #include <apos/elf.h>
+#include <apos/string.h>
 
 #include <arch/proc.h>
 
@@ -54,3 +55,25 @@ void set_thread(struct tcb *t)
 	r->sp = (long)t->thread_stack_top;
 	r->tp = (long)t->thread_storage;
 }
+
+void save_regs(struct tcb *t, void *p)
+{
+	struct riscv_regs *r = (struct riscv_regs *)(t++);
+	memcpy(p, r, sizeof(*r));
+}
+
+void load_regs(void *p, struct tcb *t)
+{
+	struct riscv_regs *r = (struct riscv_regs *)(t++);
+	memcpy(r, p, sizeof(*r));
+}
+
+void adjust_ipi(struct tcb *t)
+{
+	UNUSED(t);
+}
+
+void adjust_syscall(struct tcb *t)
+{
+	t->exec += 4;
+}
diff --git a/arch/riscv64/kernel/sbi.h b/arch/riscv64/kernel/sbi.h
index 2add35f..19cc595 100644
--- a/arch/riscv64/kernel/sbi.h
+++ b/arch/riscv64/kernel/sbi.h
@@ -106,4 +106,24 @@ static inline struct sbiret sbi_system_reset(uint32_t reset_type,
 	                 0);
 }
 
+/** Supervisor IPI extension ID. */
+#define EID_sPI 0x735049
+
+/** Supervisor IPI function ID. */
+#define FID_IPI 0
+
+/**
+ * Send IPI.
+ *
+ * @param hart_mask Bitmap of harts to send IPI to.
+ * @param hart_mask_base Base of \p hart_mask.
+ * @return SBI call return. \see sbiret.
+ */
+static inline struct sbiret sbi_send_ipi(unsigned long hart_mask,
+                                         unsigned long hart_mask_base)
+{
+	return sbi_ecall(EID_sPI, FID_IPI, hart_mask, hart_mask_base, 0, 0, 0,
+	                 0);
+}
+
 #endif /* APOS_RISCV_SBI_H */