[PATCH] binutils-2.16.90.0.3: can't compile 2.4.30

[Herbert Rosmanith]

good evening,

updating to binutils 2.16.90.0.3 today resulting in being unable
to compile 2.4.30. as it turns out, it's an assembly problem.
please accept these two patches:

(1)

# diff -uN linux-2.4.30/arch/i386/kernel/process.c linux-2.4.30.rescue/arch/i386/kernel/process.c
--- linux-2.4.30/arch/i386/kernel/process.c     Wed Nov 17 12:54:21 2004
+++ linux-2.4.30.rescue/arch/i386/kernel/process.c      Sat May 21 22:11:58 2005
@@ -5,6 +5,8 @@
  *
  *  Pentium III FXSR, SSE support
  *     Gareth Hughes <gareth@xxxxxxxxxxx>, May 2000
+ * Sat May 21 22:11:22 MEST 2005 herp - Herbert Rosmanith
+ *      minor fixes for as from binutils-2.16
  */
 
 /*
@@ -544,7 +546,7 @@
  * Save a segment.
  */
 #define savesegment(seg,value) \
-       asm volatile("movl %%" #seg ",%0":"=m" (*(int *)&(value)))
+       asm volatile("movw %%" #seg ",%0":"=m" (*(int *)&(value)))
 
 int copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
        unsigned long unused,
@@ -661,8 +663,8 @@
         * Save away %fs and %gs. No need to save %es and %ds, as
         * those are always kernel segments while inside the kernel.
         */
-       asm volatile("movl %%fs,%0":"=m" (*(int *)&prev->fs));
-       asm volatile("movl %%gs,%0":"=m" (*(int *)&prev->gs));
+       asm volatile("movw %%fs,%0":"=m" (*(int *)&prev->fs));
+       asm volatile("movw %%gs,%0":"=m" (*(int *)&prev->gs));
 
        /*
         * Restore %fs and %gs.


(2)

--- linux-2.4.30/include/asm-i386/system.h      Fri May 20 03:41:56 2005
+++ linux-2.4.30.rescue/include/asm-i386/system.h       Sat May 21 22:07:10 2005
@@ -84,7 +84,7 @@
 #define loadsegment(seg,value)                 \
        asm volatile("\n"                       \
                "1:\t"                          \
-               "movl %0,%%" #seg "\n"          \
+               "movw %0,%%" #seg "\n"          \
                "2:\n"                          \
                ".section .fixup,\"ax\"\n"      \
                "3:\t"                          \


---

long explanation follows.


I just updated binutils to 2.16.90.0.3. when compiling 2.4.30, I get
the following error:

gcc -D__KERNEL__ -I/data/root/linux-2.4.30.rescue/include -Wall
-Wstrict-prototypes -Wno-trigraphs -O2 -fno-strict-aliasing -fno-common
-fomit-frame-pointer -pipe -mpreferred-stack-boundary=2 -march=i586
-nostdinc -iwithprefix include -DKBUILD_BASENAME=process  -c -o
process.o process.c
{standard input}: Assembler messages:
{standard input}:738: Error: suffix or operands invalid for `mov'
{standard input}:739: Error: suffix or operands invalid for `mov'
{standard input}:832: Error: suffix or operands invalid for `mov'
{standard input}:833: Error: suffix or operands invalid for `mov'
{standard input}:884: Error: suffix or operands invalid for `mov'
{standard input}:885: Error: suffix or operands invalid for `mov'
{standard input}:887: Error: suffix or operands invalid for `mov'
{standard input}:899: Error: suffix or operands invalid for `mov'
make[1]: *** [process.o] Error 1

If we look at the assembly code:

   715  .globl copy_thread
   716          .type    copy_thread,@function
   717  copy_thread:
...
   737  #APP
   738          movl %fs,636(%ebx)
   739          movl %gs,640(%ebx)


then it is clear that a movl on a segreg should really be a movw.
(same error in 832, 833 and so on: movl vs. movw)

*but* ... why is this code generated in the first place? is this
a compiler problem? I'm using gss-2.95.3. copy_thread() doesn have
any asm() statement, hm, but then ... *ponder*

ok, the two line are possibly generated by this one:

   549  int copy_thread(int nr, unsigned long clone_flags, unsigned long esp,

   564
   565          savesegment(fs,p->thread.fs);
   566          savesegment(gs,p->thread.gs);


ok, I think this is the source of the error:

   546  #define savesegment(seg,value) \
   547          asm volatile("movl %%" #seg ",%0":"=m" (*(int *)&(value)))
   548


this definitely should be a movw, right?

best regards,
h.rosmanith



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