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Guess the number of arguments to a function somewhat better.

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Now GCC likes to stick a "mov %eax, %FOO" instruction before
"addl $BAR, %esp" if the function just called returns an int,
which is a very common case in the kernel.

Sponsored by: RiNet (Cronyx Plus LLC)
This commit is contained in:
Yaroslav Tykhiy 2006-06-16 11:14:54 +00:00
parent a6831e7e3a
commit 70b906ae82
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=159657
1 changed files with 8 additions and 4 deletions
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12
sys/i386/i386/db_trace.c
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@ -201,25 +201,29 @@ static int
db_numargs(fp)
struct i386_frame *fp;
{
int *argp;
char *argp;
int inst;
int args;
argp = (int *)db_get_value((int)&fp->f_retaddr, 4, FALSE);
argp = (char *)db_get_value((int)&fp->f_retaddr, 4, FALSE);
/*
* XXX etext is wrong for LKMs. We should attempt to interpret
* the instruction at the return address in all cases. This
* may require better fault handling.
*/
if (argp < (int *)btext || argp >= (int *)etext) {
if (argp < btext || argp >= etext) {
args = 5;
} else {
retry:
inst = db_get_value((int)argp, 4, FALSE);
if ((inst & 0xff) == 0x59) /* popl %ecx */
args = 1;
else if ((inst & 0xffff) == 0xc483) /* addl $Ibs, %esp */
args = ((inst >> 16) & 0xff) / 4;
else
else if ((inst & 0xf8ff) == 0xc089) { /* movl %eax, %Reg */
argp += 2;
goto retry;
} else
args = 5;
}
return (args);