com32: make com32 modules self-relocating (COM32R)

Introduce a new "COM32R" format, which is exactly like COM32 except
that they contain position-independent code.  Therefore, the core can
load them at any sufficiently aligned address; by protocol select 4K
as the alignment.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 21 insertions, 7 deletions

diff --git a/com32/include/sys/cpu.h b/com32/include/sys/cpu.h
index fcae2da1..b0a76036 100644
--- a/com32/include/sys/cpu.h
+++ b/com32/include/sys/cpu.h
@@ -23,41 +23,55 @@ static inline void cpuid_count(uint32_t op, uint32_t cnt,
 			       uint32_t *eax, uint32_t *ebx,
 			       uint32_t *ecx, uint32_t *edx)
 {
-  asm("cpuid"
-      : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
+  asm("pushl %%ebx ; cpuid ; movl %%ebx,%0 ; popl %%ebx"
+      : "=a" (*eax), "=SD" (*ebx), "=c" (*ecx), "=d" (*edx)
       : "a" (op), "c" (cnt));
 }
+
 static inline void cpuid(uint32_t op, uint32_t *eax, uint32_t *ebx,
 			 uint32_t *ecx, uint32_t *edx)
 {
-  cpuid_count(op, 0, eax, ebx, ecx, edx);
+  asm("pushl %%ebx ; cpuid ; movl %%ebx,%0 ; popl %%ebx"
+      : "=a" (*eax), "=SD" (*ebx), "=c" (*ecx), "=d" (*edx)
+      : "a" (op));
 }
+
 static inline __constfunc uint32_t cpuid_eax(uint32_t level)
 {
   uint32_t v;
 
-  asm("cpuid" : "=a" (v) : "a" (level) : "ebx", "ecx", "edx");
+  asm("pushl %%ebx ; cpuid ; popl %%ebx"
+      : "=a" (v)
+      : "a" (level)
+      : "ecx", "edx");
   return v;
 }
 static inline __constfunc uint32_t cpuid_ebx(uint32_t level)
 {
   uint32_t v;
 
-  asm("cpuid" : "=b" (v),  "+a" (level) : : "ecx", "edx");
+  asm("pushl %%ebx ; cpuid ; movl %%ebx,%0 ; popl %%ebx"
+      : "=a" (v)
+      : "a" (level)
+      : "ecx", "edx");
   return v;
 }
 static inline __constfunc uint32_t cpuid_ecx(uint32_t level)
 {
   uint32_t v;
 
-  asm("cpuid" : "=c" (v), "+a" (level) : : "ebx", "edx");
+  asm("pushl %%ebx ; cpuid ; popl %%ebx"
+      : "=c" (v), "+a" (level)
+      : : "edx");
   return v;
 }
 static inline __constfunc uint32_t cpuid_edx(uint32_t level)
 {
   uint32_t v;
 
-  asm("cpuid" : "=d" (v), "+a" (level) : : "ebx", "ecx");
+  asm("pushl %%ebx ; cpuid ; popl %%ebx"
+      : "=d" (v), "+a" (level)
+      : : "ecx");
   return v;
 }