Re: Kernel 2.1.80-4 compiled with egcs-980115

[Gabriel Paubert <paubert at iram dot es>]

On Tue, 20 Jan 1998, Kjartan Maraas wrote:

> I've just finished compiling this kernel with said
> compiler, and it seems to work just fine except that
> the de4x5 driver compiled as a module oopsed when I 
> tried to load it. I compiled in the haifa scheduler.
> 

Any of the two attached patches should cure the de4x5 problem.

The first one is an ad-hoc patch of drivers/net/de4x5.c,
use it if you are conservative.

The second one is an attempt of a generic patch to cure bugs
in include/asm-i386/string.h, it is more risky but up to now
I have only got success reports (admittedly few). 

Using both is essentially useless, but should not do any harm. 

  Gabriel.
--- linux-2.0.30/drivers/net/de4x5.c.virgin	Sun Oct  5 18:39:18 1997
+++ linux-2.0.30/drivers/net/de4x5.c	Sun Oct  5 18:54:38 1997
@@ -3026,10 +3026,11 @@
 /*
 ** Look for a particular board name in the EISA configuration space
 */
+static c_char * const signatures[] = DE4X5_SIGNATURE;
+
 static int
 EISA_signature(char *name, s32 eisa_id)
 {
-    c_char *signatures[] = DE4X5_SIGNATURE;
     char ManCode[DE4X5_STRLEN];
     union {
 	s32 ID;
@@ -3064,8 +3065,7 @@
 static int
 PCI_signature(char *name, struct bus_type *lp)
 {
-    c_char *de4x5_signatures[] = DE4X5_SIGNATURE;
-    int i, status = 0, siglen = sizeof(de4x5_signatures)/sizeof(c_char *);
+    int i, status = 0, siglen = sizeof(signatures)/sizeof(c_char *);
     
     if (lp->chipset == DC21040) {
 	strcpy(name, "DE434/5");
@@ -3079,7 +3079,7 @@
     }
     name[8] = '\0';
     for (i=0; i<siglen; i++) {
-	if (strstr(name,de4x5_signatures[i])!=NULL) break;
+	if (strstr(name,signatures[i])!=NULL) break;
     }
     if (i == siglen) {
 	if (dec_only) {
--- linux-2.0.30/include/asm-i386/string.h.virgin	Wed Oct  1 10:55:48 1997
+++ linux-2.0.30/include/asm-i386/string.h	Thu Oct  2 21:52:47 1997
@@ -26,6 +26,23 @@
  *		Copyright (C) 1991, 1992 Linus Torvalds
  */
 
+/* 
+ * Found a serious problem with constraints revealed by compiling with pgcc.
+ * 
+ * First attempt to fix it by G.Paubert, paubert@iram.es, 1997
+ * 
+ * Consider for now this code as experimentation on gcc inline assembly. 
+ * Use at your own risk. 
+ *
+ * I have also the feeling that many "memory" are superfluous:
+ * when passing a char *, resp. a const char *, the compiler should assume 
+ * that the value or array pointed to is modified, resp referenced.
+ * The fact that the function is declared extern inline should not change
+ * these semantics. 
+ * 
+ */
+
+
 #define __HAVE_ARCH_STRCPY
 extern inline char * strcpy(char * dest,const char *src)
 {
@@ -36,7 +53,7 @@
 	"testb %%al,%%al\n\t"
 	"jne 1b"
 	: /* no output */
-	:"S" (src),"D" (dest):"si","di","ax","memory");
+	:"S" (src),"D" (dest):"si","di","ax"/*,"memory"*/);
 return dest;
 }
 
@@ -55,7 +72,7 @@
 	"stosb\n"
 	"2:"
 	: /* no output */
-	:"S" (src),"D" (dest),"c" (count):"si","di","ax","cx","memory");
+	:"S" (src),"D" (dest),"c" (count):"si","di","ax","cx"/*,"memory"*/);
 return dest;
 }
 
@@ -95,7 +112,7 @@
 	"stosb"
 	: /* no output */
 	:"S" (src),"D" (dest),"a" (0),"c" (0xffffffff),"g" (count)
-	:"si","di","ax","cx","memory");
+	:"si","di","ax","cx"/*,"memory"*/);
 return dest;
 }
 
@@ -181,25 +198,29 @@
 extern inline size_t strspn(const char * cs, const char * ct)
 {
 register char * __res;
+const char * __ct;
+int __len;
 __asm__ __volatile__(
 	"cld\n\t"
-	"movl %4,%%edi\n\t"
+	"movl %6,%%edi\n\t"
 	"repne\n\t"
 	"scasb\n\t"
 	"notl %%ecx\n\t"
-	"decl %%ecx\n\t"
-	"movl %%ecx,%%edx\n"
+	"leal -1(%%ecx),%1\n\t"
 	"1:\tlodsb\n\t"
 	"testb %%al,%%al\n\t"
 	"je 2f\n\t"
-	"movl %4,%%edi\n\t"
-	"movl %%edx,%%ecx\n\t"
+	"movl %6,%%edi\n\t"
+	"movl %1,%%ecx\n\t"
 	"repne\n\t"
 	"scasb\n\t"
 	"je 1b\n"
 	"2:\tdecl %0"
-	:"=S" (__res):"a" (0),"c" (0xffffffff),"0" (cs),"g" (ct)
-	:"ax","cx","dx","di");
+	/* This constraint set leaves few choices to gcc, but usually works.
+	   Change "=&r" (__len) to "=&rm" (__len) if the compiler complains. */
+	:"=S" (__res), "=&r" (__len), "=&D" (__ct)
+	:"a" (0),"c" (0xffffffff),"0" (cs), "g" (ct)
+	:"ax","cx");
 return __res-cs;
 }
 
@@ -207,83 +228,95 @@
 extern inline size_t strcspn(const char * cs, const char * ct)
 {
 register char * __res;
+const char * __ct;
+int __len;
 __asm__ __volatile__(
 	"cld\n\t"
-	"movl %4,%%edi\n\t"
+	"movl %6,%%edi\n\t"
 	"repne\n\t"
 	"scasb\n\t"
 	"notl %%ecx\n\t"
-	"decl %%ecx\n\t"
-	"movl %%ecx,%%edx\n"
+	"leal -1(%%ecx),%1\n\t"
 	"1:\tlodsb\n\t"
 	"testb %%al,%%al\n\t"
 	"je 2f\n\t"
-	"movl %4,%%edi\n\t"
-	"movl %%edx,%%ecx\n\t"
+	"movl %6,%%edi\n\t"
+	"movl %1,%%ecx\n\t"
 	"repne\n\t"
 	"scasb\n\t"
 	"jne 1b\n"
 	"2:\tdecl %0"
-	:"=S" (__res):"a" (0),"c" (0xffffffff),"0" (cs),"g" (ct)
-	:"ax","cx","dx","di");
+	/* This constraint set leaves few choices to gcc, but usually works.
+	   Change "=&r" (__len) to "=&rm" (__len) if the compiler complains. */
+	:"=S" (__res), "=&r" (__len), "=&D" (__ct)
+	:"a" (0),"c" (0xffffffff),"0" (cs),"g" (ct)
+	:"ax","cx");
 return __res-cs;
 }
 
 #define __HAVE_ARCH_STRPBRK
 extern inline char * strpbrk(const char * cs,const char * ct)
 {
-register char * __res;
+char * __res;
+const char * __ct;
+int __len;
 __asm__ __volatile__(
 	"cld\n\t"
-	"movl %4,%%edi\n\t"
+	"movl %6,%%edi\n\t"
 	"repne\n\t"
 	"scasb\n\t"
 	"notl %%ecx\n\t"
-	"decl %%ecx\n\t"
-	"movl %%ecx,%%edx\n"
+	"leal -1(%%ecx),%1\n\t"
 	"1:\tlodsb\n\t"
 	"testb %%al,%%al\n\t"
-	"je 2f\n\t"
-	"movl %4,%%edi\n\t"
-	"movl %%edx,%%ecx\n\t"
+	"je 2f\n\t"		/* Here %eax is zero if branch taken ! */
+	"movl %6,%%edi\n\t"
+	"movl %1,%%ecx\n\t"
 	"repne\n\t"
 	"scasb\n\t"
 	"jne 1b\n\t"
-	"decl %0\n\t"
-	"jmp 3f\n"
-	"2:\txorl %0,%0\n"
-	"3:"
-	:"=S" (__res):"a" (0),"c" (0xffffffff),"0" (cs),"g" (ct)
-	:"ax","cx","dx","di");
+	"leal -1(%%esi),%%eax\n\t"
+	"2:"
+	/* This constraint set leaves few choices to gcc, but usually works.
+	   Change "=&r" (__len) to "=&rm" (__len) if the compiler complains. */
+	:"=a" (__res),  "=&r" (__len), "=&D" (__ct)
+	:"0" (0),"c" (0xffffffff),"S" (cs),"g" (ct)
+	:"cx","si");
 return __res;
 }
 
 #define __HAVE_ARCH_STRSTR
 extern inline char * strstr(const char * cs,const char * ct)
 {
-register char * __res;
+char * __res;
+const char *__ct;
+int __len;
 __asm__ __volatile__(
-	"cld\n\t" \
-	"movl %4,%%edi\n\t"
+	"cld\n\t"
+	"movl %6,%%edi\n\t"
 	"repne\n\t"
 	"scasb\n\t"
 	"notl %%ecx\n\t"
 	"decl %%ecx\n\t"	/* NOTE! This also sets Z if searchstring='' */
-	"movl %%ecx,%%edx\n"
-	"1:\tmovl %4,%%edi\n\t"
+	"movl %%ecx,%1\n"
+	"1:\tmovl %6,%%edi\n\t"
 	"movl %%esi,%%eax\n\t"
-	"movl %%edx,%%ecx\n\t"
 	"repe\n\t"
 	"cmpsb\n\t"
 	"je 2f\n\t"		/* also works for empty string, see above */
 	"xchgl %%eax,%%esi\n\t"
+	"movl %1,%%ecx\n\t"
 	"incl %%esi\n\t"
 	"cmpb $0,-1(%%eax)\n\t"
 	"jne 1b\n\t"
 	"xorl %%eax,%%eax\n\t"
 	"2:"
-	:"=a" (__res):"0" (0),"c" (0xffffffff),"S" (cs),"g" (ct)
-	:"cx","dx","di","si");
+	/* This constraint set leaves few choices to gcc, but usually works,
+	 and pgcc complains with impossible constraints if __len is declared
+	 as "=&r" when compiling de4x5.c ! */
+	:"=a" (__res),  "=&rm" (__len), "=&D" (__ct)
+	:"0" (0),"c" (0xffffffff),"S" (cs),"g" (ct)
+	:"cx","si");
 return __res;
 }
 
@@ -304,7 +337,9 @@
 #define __HAVE_ARCH_STRTOK
 extern inline char * strtok(char * s,const char * ct)
 {
-register char * __res;
+char * __res;
+const char * __ct;
+int __len, __cnt, __val;
 __asm__ __volatile__(
 	"testl %1,%1\n\t"
 	"jne 1f\n\t"
@@ -315,18 +350,18 @@
 	"movl $-1,%%ecx\n\t"
 	"xorl %%eax,%%eax\n\t"
 	"cld\n\t"
-	"movl %4,%%edi\n\t"
+	"movl %8,%%edi\n\t"
 	"repne\n\t"
 	"scasb\n\t"
 	"notl %%ecx\n\t"
 	"decl %%ecx\n\t"
 	"je 7f\n\t"			/* empty delimiter-string */
-	"movl %%ecx,%%edx\n"
+	"movl %%ecx,%2\n"
 	"2:\tlodsb\n\t"
 	"testb %%al,%%al\n\t"
 	"je 7f\n\t"
-	"movl %4,%%edi\n\t"
-	"movl %%edx,%%ecx\n\t"
+	"movl %8,%%edi\n\t"
+	"movl %2,%%ecx\n\t"
 	"repne\n\t"
 	"scasb\n\t"
 	"je 2b\n\t"
@@ -337,8 +372,8 @@
 	"3:\tlodsb\n\t"
 	"testb %%al,%%al\n\t"
 	"je 5f\n\t"
-	"movl %4,%%edi\n\t"
-	"movl %%edx,%%ecx\n\t"
+	"movl %8,%%edi\n\t"
+	"movl %2,%%ecx\n\t"
 	"repne\n\t"
 	"scasb\n\t"
 	"jne 3b\n\t"
@@ -356,9 +391,12 @@
 	"jne 8f\n\t"
 	"movl %0,%1\n"
 	"8:"
-	:"=b" (__res),"=S" (___strtok)
-	:"0" (___strtok),"1" (s),"g" (ct)
-	:"ax","cx","dx","di","memory");
+	/* This constraint set is frightening: if I were the compiler, 
+	   I would try to eat the source file to avoid seeing it again :-).
+	   Change "=&r" (__len) to "=&rm" (__len) if the compiler complains. */
+	:"=b" (__res),"=S" (___strtok), "=&r" (__len), "=&D" (__ct), 
+	 "=&c" (__cnt), "=&a" (__val)
+	:"0" (___strtok),"1" (s),"g" (ct));
 return __res;
 }