Fix catastrophic bug in proc_switch. Remove unneeded comments.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@1044 38d2e660-2303-0410-9eaa-f027e97ec537

diff --git a/kern/proc.c b/kern/proc.c
index f86e1ad9113c16805b66e6c90170b6d388315392..f28b9819fa88e3d3251c427e2df318efa352475c 100644 (file)
--- a/kern/proc.c
+++ b/kern/proc.c
@@ -49,6 +49,7 @@
 #include <cpu/types.h>
 #include <cpu/attr.h>
 #include <cfg/debug.h>
+#include <cfg/module.h>
 #include <cfg/arch_config.h>  /* ARCH_EMUL */
 #include <cfg/macros.h>  /* ABS() */
 
@@ -109,6 +110,7 @@ static void proc_init_struct(Process *proc)
 #endif
 }
 
+MOD_DEFINE(proc);
 
 void proc_init(void)
 {
@@ -127,6 +129,7 @@ void proc_init(void)
 
        /* Make sure the assembly routine is up-to-date with us */
        ASSERT(asm_switch_version() == 1);
+       MOD_INIT(proc);
 }
 
 
@@ -240,12 +243,8 @@ void proc_rename(struct Process *proc, const char *name)
  */
 void proc_schedule(void)
 {
-       /* This function must not have any "auto" variables, otherwise
-        * the compiler might put them on the stack of the process
-        * being switched out.
-        */
-       static struct Process *old_process;
-       static cpuflags_t flags;
+       struct Process *old_process;
+       cpuflags_t flags;
 
        /* Remember old process to save its context later */
        old_process = CurrentProcess;
@@ -281,7 +280,7 @@ void proc_schedule(void)
         */
        if (CurrentProcess != old_process)
        {
-               static cpustack_t *dummy;
+               cpustack_t *dummy;
 
 #if CONFIG_KERN_PREEMPTIVE
                /* Reset quantum for this process */
@@ -348,8 +347,7 @@ void proc_exit(void)
  */
 void proc_switch(void)
 {
-       /* Just like proc_schedule, this function must not have auto variables. */
-       static cpuflags_t flags;
+       cpuflags_t flags;
 
        IRQ_SAVE_DISABLE(flags);
        SCHED_ENQUEUE(CurrentProcess);

diff --git a/kern/switch_avr.S b/kern/switch_avr.S
index 84fa14d3287af07337649412ce29d9a2e8bd3233..93892919ff483d5bdae0a915042c2fd799c00605 100644 (file)
--- a/kern/switch_avr.S
+++ b/kern/switch_avr.S
@@ -26,10 +26,15 @@
 .globl asm_switch_context
 asm_switch_context:
 
+;      r0 is the TEMP REG and can be used freely.
+;      r1 is the ZERO REG and must always contain 0.
+;
+;      Stack frame is 19 byte, remember to update
+;      CPU_SAVED_REGS_CNT if you change pushed regs.
+
        in      r0,SREG-__SFR_OFFSET
        push    r0
-;      push    r0      caller-save
-;      push    r1      caller-save
+;      push    r1      ;zero-reg
        push    r2
        push    r3
        push    r4
@@ -46,48 +51,58 @@ asm_switch_context:
        push    r15
        push    r16
        push    r17
-;      push    r18     caller-save
-;      push    r19     caller-save
-;      push    r20     caller-save
-;      push    r21     caller-save
-;      push    r22     caller-save
-;      push    r23     caller-save
-;      push    r24     caller-save
-;      push    r25     caller-save
-;      push    r26     caller-save
-;      push    r27     caller-save
+;      push    r18     ;caller-save
+;      push    r19     ;caller-save
+;      push    r20     ;caller-save
+;      push    r21     ;caller-save
+;      push    r22     ;caller-save
+;      push    r23     ;caller-save
+;      push    r24     ;caller-save
+;      push    r25     ;caller-save
+;      push    r26     ;caller-save
+;      push    r27     ;caller-save
        push    r28
        push    r29
-;      push    r30     caller-save
-;      push    r31     caller-save
+;      push    r30     ;caller-save
+;      push    r31     ;caller-save
 
-; First parameter (new_sp) is in r24:r25, second (save_sp) in r22:r23
+;      First parameter (new_sp) is in r24:r25, second (save_sp) in r22:r23
 
-       in      r0,SPL-__SFR_OFFSET     ; r0:r1 = SP
-       in      r1,SPH-__SFR_OFFSET
+       in      r18,SPL-__SFR_OFFSET    ; r18:r19 = SP
+       in      r19,SPH-__SFR_OFFSET
        movw    r26,r22                 ; X = save_sp
-       st      X+,r0                   ; *save_sp = SP
-       st      X,r1
+       st      X+,r18                  ; *save_sp = SP
+       st      X,r19
        movw    r26,r24                 ; X = new_sp
-       ld      r0,X+
-       ld      r1,X
-       out     SPL-__SFR_OFFSET,r0     ; SP = *new_sp
-       out     SPH-__SFR_OFFSET,r1
+       ld      r18,X+
+       ld      r19,X
+
+;      Set new stack pointer.
+;      AVR is an 8 bit processor so
+;      care must be taken when updating
+;      SP that is a 16 bit reg.
+;      Two instructions are required to update SP
+;      so an IRQ can sneak in between them.
+;      So IRQ *MUST* be disabled and then restored.
+       cli                             ; Disable interrupt
+       out     SPL-__SFR_OFFSET,r18    ; SP = *new_sp
+       out     SPH-__SFR_OFFSET,r19
+       out     SREG-__SFR_OFFSET,r0    ; Restore previous IRQ state
 
-;      pop     r31     caller-save
-;      pop     r30     caller-save
+;      pop     r31     ;caller-save
+;      pop     r30     ;caller-save
        pop     r29
        pop     r28
-;      pop     r27     caller-save
-;      pop     r26     caller-save
-;      pop     r25     caller-save
-;      pop     r24     caller-save
-;      pop     r23     caller-save
-;      pop     r22     caller-save
-;      pop     r21     caller-save
-;      pop     r20     caller-save
-;      pop     r19     caller-save
-;      pop     r18     caller-save
+;      pop     r27     ;caller-save
+;      pop     r26     ;caller-save
+;      pop     r25     ;caller-save
+;      pop     r24     ;caller-save
+;      pop     r23     ;caller-save
+;      pop     r22     ;caller-save
+;      pop     r21     ;caller-save
+;      pop     r20     ;caller-save
+;      pop     r19     ;caller-save
+;      pop     r18     ;caller-save
        pop     r17
        pop     r16
        pop     r15
@@ -104,8 +119,7 @@ asm_switch_context:
        pop     r4
        pop     r3
        pop     r2
-;      pop     r1      caller-save
-;      pop     r0      caller-save
+;      pop     r1      ;zero-reg
        pop     r0
        out     SREG-__SFR_OFFSET,r0