[Xen-devel] [PATCH] [Mini-OS] Fix x86 arch_switch_thread

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>]

Fix x86 arch_switch_thread by making it pure assembly.
There were missing general register clobbers for x86_64, and BP should
theorically be clobbered too, but gcc does not believe that, so the only
simple safe solution is to use pure assembly

Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxx>

diff -r 2e05a6173be0 extras/mini-os/arch/x86/x86_32.S
--- a/extras/mini-os/arch/x86/x86_32.S  Fri Nov 23 11:58:11 2007 +0000
+++ b/extras/mini-os/arch/x86/x86_32.S  Fri Nov 23 15:58:24 2007 +0000
@@ -283,3 +283,21 @@
     call *%ebx
     call exit_thread 
     
+ENTRY(__arch_switch_threads)
+    movl 4(%esp), %ecx         /* prev */
+    movl 8(%esp), %edx         /* next */
+    pushl %ebp
+    pushl %ebx
+    pushl %esi
+    pushl %edi
+    movl %esp, (%ecx)          /* save ESP */
+    movl (%edx), %esp          /* restore ESP */
+    movl $1f, 4(%ecx)          /* save EIP */
+    pushl 4(%edx)              /* restore EIP */
+    ret
+1:
+    popl %edi
+    popl %esi
+    popl %ebx
+    popl %ebp
+    ret
diff -r 2e05a6173be0 extras/mini-os/arch/x86/x86_64.S
--- a/extras/mini-os/arch/x86/x86_64.S  Fri Nov 23 11:58:11 2007 +0000
+++ b/extras/mini-os/arch/x86/x86_64.S  Fri Nov 23 15:58:24 2007 +0000
@@ -382,3 +378,23 @@
         call exit_thread 
         
 
+ENTRY(__arch_switch_threads)
+       pushq %rbp
+       pushq %rbx
+       pushq %r12
+       pushq %r13
+       pushq %r14
+       pushq %r15
+       movq %rsp, (%rdi)               /* save ESP */
+       movq (%rsi), %rsp               /* restore ESP */
+       movq $1f, 8(%rdi)               /* save EIP */
+       pushq 8(%rsi)                   /* restore EIP */
+       ret
+1:
+       popq %r15
+       popq %r14
+       popq %r13
+       popq %r12
+       popq %rbx
+       popq %rbp
+       ret
diff -r 2e05a6173be0 extras/mini-os/include/x86/arch_sched.h
--- a/extras/mini-os/include/x86/arch_sched.h   Fri Nov 23 11:58:11 2007 +0000
+++ b/extras/mini-os/include/x86/arch_sched.h   Fri Nov 23 15:58:24 2007 +0000
@@ -11,44 +4,9 @@
     return *current;
 }
 
-#ifdef __i386__
-#define arch_switch_threads(prev, next) do {                            \
-    unsigned long esi,edi;                                              \
-    __asm__ __volatile__("pushfl\n\t"                                   \
-                         "pushl %%ebp\n\t"                              \
-                         "movl %%esp,%0\n\t"         /* save ESP */     \
-                         "movl %4,%%esp\n\t"        /* restore ESP */   \
-                         "movl $1f,%1\n\t"          /* save EIP */      \
-                         "pushl %5\n\t"             /* restore EIP */   \
-                         "ret\n\t"                                      \
-                         "1:\t"                                         \
-                         "popl %%ebp\n\t"                               \
-                         "popfl"                                        \
-                         :"=m" (prev->sp),"=m" (prev->ip),            \
-                          "=S" (esi),"=D" (edi)             \
-                         :"m" (next->sp),"m" (next->ip),              \
-                          "2" (prev), "d" (next));                      \
-} while (0)
-#elif __x86_64__
-#define arch_switch_threads(prev, next) do {                                 \
-    unsigned long rsi,rdi;                                              \
-    __asm__ __volatile__("pushfq\n\t"                                   \
-                         "pushq %%rbp\n\t"                              \
-                         "movq %%rsp,%0\n\t"         /* save RSP */     \
-                         "movq %4,%%rsp\n\t"        /* restore RSP */   \
-                         "movq $1f,%1\n\t"          /* save RIP */      \
-                         "pushq %5\n\t"             /* restore RIP */   \
-                         "ret\n\t"                                      \
-                         "1:\t"                                         \
-                         "popq %%rbp\n\t"                               \
-                         "popfq"                                        \
-                         :"=m" (prev->sp),"=m" (prev->ip),            \
-                          "=S" (rsi),"=D" (rdi)             \
-                         :"m" (next->sp),"m" (next->ip),              \
-                          "2" (prev), "d" (next));                      \
-} while (0)
-#endif
+extern void __arch_switch_threads(unsigned long *prevctx, unsigned long 
*nextctx);
 
+#define arch_switch_threads(prev,next) __arch_switch_threads(&(prev)->sp, 
&(next)->sp)
 
 
           
diff -r f2711b7eae95 -r 36bf1e737b87 extras/mini-os/include/sched.h
--- a/extras/mini-os/include/sched.h    Thu Nov 22 19:55:42 2007 +0000
+++ b/extras/mini-os/include/sched.h    Fri Nov 23 13:21:02 2007 +0000
@@ -10,6 +10,7 @@ struct thread
     char *name;
     char *stack;
 #if !defined(__ia64__)
+    /* keep in that order */
     unsigned long sp;  /* Stack pointer */
     unsigned long ip;  /* Instruction pointer */
 #else /* !defined(__ia64__) */

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