altos: Be more careful about register save/restore in ao_yield

Make sure the general registers are all saved before messing with any
of them. Then, explicitly use r0 to save/restore apsr and primask.

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/src/stm/ao_arch.h b/src/stm/ao_arch.h
index 62af86f776faba6cd1ac17c64256b4336e6c06aa..bbd1b3b1f33e50a90bed62d4178fd689789f77d6 100644 (file)
--- a/src/stm/ao_arch.h
+++ b/src/stm/ao_arch.h
@@ -74,12 +74,6 @@ extern const uint16_t ao_serial_number;
                uint32_t        a = (uint32_t) start;                   \
                int             i;                                      \
                                                                        \
-               /* APSR */                                              \
-               ARM_PUSH32(sp, 0);                                      \
-                                                                       \
-               /* PRIMASK with interrupts enabled */                   \
-               ARM_PUSH32(sp, 0);                                      \
-                                                                       \
                /* Return address (goes into LR) */                     \
                ARM_PUSH32(sp, a);                                      \
                                                                        \
@@ -88,23 +82,29 @@ extern const uint16_t ao_serial_number;
                while (i--)                                             \
                        ARM_PUSH32(sp, 0);                              \
                                                                        \
+               /* APSR */                                              \
+               ARM_PUSH32(sp, 0);                                      \
+                                                                       \
+               /* PRIMASK with interrupts enabled */                   \
+               ARM_PUSH32(sp, 0);                                      \
+                                                                       \
                task->sp = sp;                                          \
 } while (0);
        
 #define ao_arch_save_regs()    do {                                    \
-               uint32_t        apsr;                                   \
-               uint32_t        primask;                                \
+               /* Save general registers */                            \
+               asm("push {r0-r12,lr}\n");                              \
                                                                        \
                /* Save APSR */                                         \
-               asm("mrs %0,apsr" : "=&r" (apsr));                      \
-               asm("push {%0}" : : "r" (apsr));                        \
+               asm("mrs r0,apsr");                                     \
+               asm("push {r0}");                                       \
                                                                        \
                /* Save PRIMASK */                                      \
-               asm("mrs %0,primask" : "=&r" (primask));                \
-               asm("push {%0}" : : "r" (primask));                     \
+               asm("mrs r0,primask");                                  \
+               asm("push {r0}");                                       \
                                                                        \
-               /* Save general registers */                            \
-               asm("push {r0-r12,lr}\n");                              \
+               /* Enable interrupts */                                 \
+               sei();                                                  \
        } while (0)
 
 #define ao_arch_save_stack() do {                                      \
@@ -123,23 +123,21 @@ extern const uint16_t ao_serial_number;
 
 #define ao_arch_restore_stack() do { \
                uint32_t        sp;                                     \
-               uint32_t        primask;                                \
-               uint32_t        apsr;                                   \
                sp = (uint32_t) ao_cur_task->sp;                        \
                                                                        \
                /* Switch stacks */                                     \
                asm("mov sp, %0" : : "r" (sp) );                        \
                                                                        \
-               /* Restore general registers */                         \
-               asm("pop {r0-r12,lr}\n");                               \
-                                                                       \
                /* Restore PRIMASK */                                   \
-               asm("pop {%0}" : "=&r" (primask) );                     \
-               asm("msr primask,%0" : : "r" (primask) );               \
+               asm("pop {r0}");                                        \
+               asm("msr primask,r0");                                  \
                                                                        \
                /* Restore APSR */                                      \
-               asm("pop {%0}" : "=&r" (apsr) );                        \
-               asm("msr apsr,%0" : : "r" (apsr) );                     \
+               asm("pop {r0}");                                        \
+               asm("msr apsr,r0");                                     \
+                                                                       \
+               /* Restore general registers */                         \
+               asm("pop {r0-r12,lr}\n");                               \
                                                                        \
                /* Return to calling function */                        \
                asm("bx lr");                                           \