[Minios-devel] [PATCH 20/40] arm64: implement the __arch_switch_threads

[Huang Shijie <shijie.huang@xxxxxxx>]

The __arch_switch_threads is used for switching the threads.
This patch implements it, and defines the stack layout.

Change-Id: I195df8a34ad4738c3e3e925e6d7ed1c46eece0c8
Jira: ENTOS-247
Signed-off-by: Huang Shijie <shijie.huang@xxxxxxx>
---
 arch/arm/arm64/arm64.S | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++
 include/arm/arm64/os.h |  3 +++
 2 files changed, 62 insertions(+)

diff --git a/arch/arm/arm64/arm64.S b/arch/arm/arm64/arm64.S
index e16ef95..6dab875 100644
--- a/arch/arm/arm64/arm64.S
+++ b/arch/arm/arm64/arm64.S
@@ -1,6 +1,7 @@
 #include "asm.h"
 #include <arm64/pagetable.h>
 #include <xen/xen.h>
+#include <arm64/os.h>
 
 /* This macro will use the x0/x1/x2/x16 */
 #define PRINT(_s)                              \
@@ -461,3 +462,61 @@ el_invalid(el1_fiq, BAD_FIQ, 1);
 el_invalid(el0_fiq, BAD_FIQ, 0);
 el_invalid(el1_error, BAD_ERROR, 1);
 el_invalid(el0_error, BAD_ERROR, 0);
+
+/*
+ * => x0 = &prev->sp
+ *    x1 = &next->sp
+ * <= switch to the next thread
+ *
+ *  The stack layout shows below:
+ *
+ *                    ---------------
+ *                   |      lr       |
+ *                   |---------------|
+ *                   |  User data    |
+ *                   |---------------|
+ *                   |      sp       |    -----------------
+ *                   |---------------|          |
+ *                   |      x29      |          |
+ *                   |---------------|          v
+ *                   |      x28      |
+ *                   |---------------|  CALLEE_SAVED_REGISTERS
+ *                   |     .....     |
+ *                   |---------------|          ^
+ *                   |      x20      |          |
+ *                   |---------------|          |
+ *    thread->sp --> |      x19      |    -----------------
+ *                   |---------------|
+ */
+ENTRY(__arch_switch_threads)
+    /* Store the callee-saved registers and lr(x30) */
+    mov   x4, sp
+
+    ldr   x2, [x0]
+    stp   x19, x20, [x2, #16 * 0]
+    stp   x21, x22, [x2, #16 * 1]
+    stp   x23, x24, [x2, #16 * 2]
+    stp   x25, x26, [x2, #16 * 3]
+    stp   x27, x28, [x2, #16 * 4]
+    stp   x29, x4,  [x2, #16 * 5]
+
+    add   x2, x2, #(CALLEE_SAVED_REGISTERS * 8)
+    add   x2, x2, #8             /* skip the user data */
+    str   x30, [x2]
+
+    /* Restore the callee-saved registers and lr(x30) */
+    ldr   x2, [x1]
+    ldp   x19, x20, [x2, #16 * 0]
+    ldp   x21, x22, [x2, #16 * 1]
+    ldp   x23, x24, [x2, #16 * 2]
+    ldp   x25, x26, [x2, #16 * 3]
+    ldp   x27, x28, [x2, #16 * 4]
+    ldp   x29, x4,  [x2, #16 * 5]
+
+    add   x2, x2, #(CALLEE_SAVED_REGISTERS * 8)
+    add   x2, x2, #8             /* skip the user data */
+    ldr   x30, [x2]
+
+    mov   sp,  x4
+    ret
+ENDPROC(__arch_switch_threads)
diff --git a/include/arm/arm64/os.h b/include/arm/arm64/os.h
index 9c36a2c..1ffd99b 100644
--- a/include/arm/arm64/os.h
+++ b/include/arm/arm64/os.h
@@ -1,6 +1,7 @@
 #ifndef _ARM64_OS_H_
 #define _ARM64_OS_H_
 
+#ifndef __ASSEMBLY__
 static inline void local_irq_disable(void)
 {
     __asm__ __volatile__("msr daifset, #2": : :"memory");
@@ -32,6 +33,8 @@ static inline void local_irq_enable(void)
 #define wmb()           dmb(st) /* Full system memory barrier store */
 #define rmb()           dmb(ld) /* Full system memory barrier load */
 
+#endif
+
 /* The Callee-saved registers : x19 ~ x29, and SP */
 #define CALLEE_SAVED_REGISTERS 12
 
-- 
2.7.4


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