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-rw-r--r--.gitignore1
-rw-r--r--bsp/env/start.S51
-rw-r--r--software/smp/Makefile6
-rw-r--r--software/smp/atomic.h29
-rw-r--r--software/smp/smp.c40
5 files changed, 126 insertions, 1 deletions
diff --git a/.gitignore b/.gitignore
index 29d3e10..534c2dc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,3 +13,4 @@ software/hello/hello
software/led_fade/led_fade
software/local_interrupts/local_interrupts
software/performance_counters/performance_counters
+software/smp/smp
diff --git a/bsp/env/start.S b/bsp/env/start.S
index e86105b..4e9f665 100644
--- a/bsp/env/start.S
+++ b/bsp/env/start.S
@@ -1,18 +1,27 @@
// See LICENSE for license details.
+#include <sifive/smp.h>
-// See LICENSE for license details.
+/* This is defined in sifive/platform.h, but that can't be included from
+ * assembly. */
+#define CLINT_CTRL_ADDR 0x02000000
.section .init
.globl _start
.type _start,@function
_start:
+ .cfi_startproc
+ .cfi_undefined ra
.option push
.option norelax
la gp, __global_pointer$
.option pop
la sp, _sp
+#if defined(ENABLE_SMP)
+ smp_pause(t0, t1)
+#endif
+
/* Load data section */
la a0, _data_lma
la a1, _data
@@ -52,11 +61,51 @@ _start:
1:
#endif
+#if defined(ENABLE_SMP)
+ smp_resume(t0, t1)
+
+ csrr a0, mhartid
+ bnez a0, 2f
+#endif
+
+ auipc ra, 0
+ addi sp, sp, -16
+#if __riscv_xlen == 32
+ sw ra, 8(sp)
+#else
+ sd ra, 8(sp)
+#endif
+
/* argc = argv = 0 */
li a0, 0
li a1, 0
call main
tail exit
+1:
+ j 1b
+
+#if defined(ENABLE_SMP)
+2:
+ la t0, trap_entry
+ csrw mtvec, t0
+
+ csrr a0, mhartid
+ la t1, _sp
+ slli t0, a0, 10
+ sub sp, t1, t0
+
+ auipc ra, 0
+ addi sp, sp, -16
+#if __riscv_xlen == 32
+ sw ra, 8(sp)
+#else
+ sd ra, 8(sp)
+#endif
+
+ call secondary_main
+ tail exit
1:
j 1b
+#endif
+ .cfi_endproc
diff --git a/software/smp/Makefile b/software/smp/Makefile
new file mode 100644
index 0000000..4131ffc
--- /dev/null
+++ b/software/smp/Makefile
@@ -0,0 +1,6 @@
+TARGET = smp
+C_SRCS += smp.c
+CFLAGS += -O2 -fno-builtin-printf -DENABLE_SMP
+
+BSP_BASE = ../../bsp
+include $(BSP_BASE)/env/common.mk
diff --git a/software/smp/atomic.h b/software/smp/atomic.h
new file mode 100644
index 0000000..074c6a2
--- /dev/null
+++ b/software/smp/atomic.h
@@ -0,0 +1,29 @@
+#ifndef SIFIVE_ATOMIC_H
+#define SIFIVE_ATOMIC_H
+
+#define ATOMIC_INIT(x) \
+ { \
+ .counter = (x), \
+ }
+
+typedef struct {
+ int counter;
+} atomic_t;
+
+static inline int atomic_xchg(atomic_t *v, int n)
+{
+ register int c;
+
+ __asm__ __volatile__ (
+ "amoswap.w.aqrl %0, %2, %1"
+ : "=r" (c), "+A" (v->counter)
+ : "r" (n));
+ return c;
+}
+
+static inline void mb(void)
+{
+ __asm__ __volatile__ ("fence");
+}
+
+#endif
diff --git a/software/smp/smp.c b/software/smp/smp.c
new file mode 100644
index 0000000..36c9db9
--- /dev/null
+++ b/software/smp/smp.c
@@ -0,0 +1,40 @@
+#include <stdio.h>
+#include <unistd.h>
+#include "atomic.h"
+void write_hex(int, unsigned long);
+
+atomic_t tty_lock = ATOMIC_INIT(0);
+
+void get_lock(atomic_t *lock)
+{
+ while (atomic_xchg(lock, 1) == 1);
+ mb();
+}
+
+void put_lock(atomic_t *lock)
+{
+ mb();
+ atomic_xchg(lock, 0);
+}
+
+int secondary_main(int hartid)
+{
+ volatile int counter;
+
+ while (1) {
+ get_lock(&tty_lock);
+ write(1, "hello world from hart ", 22);
+ char s[] = {'0', '\n', '\0'};
+ s[0] += hartid;
+ write(1, s, 2);
+ put_lock(&tty_lock);
+
+ for (counter = 0; counter < 10000 + 100*hartid; ++counter)
+ mb();
+ }
+}
+
+int main()
+{
+ return secondary_main(0);
+}