Date: Wed, 19 Dec 2001 16:01:03 -0500 From: Daniel Eischen <eischen@vigrid.com> To: current@freebsd.org Cc: alpha@freebsd.org Subject: Munging jmp_bufs on alpha Message-ID: <3C21000F.994BD53D@vigrid.com>
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libc_r seems to be broke on alpha and I'm trying to fix it.
We munge jmp_bufs to create new contexts for threads and for
the thread scheduler. It seems that sometime over the last
few weeks/months something broke that. It doesn't look like
_setjmp of _longjmp have changed at all, though.
Included is a sample program that includes the jmp_buf-munging
macros that use to work and that no longer work. [ Drew, you
out there? You got these to work before ;-) ]
Any help would be appreciated.
Thanks,
--
Dan Eischen
--------------
#include <unistd.h>
#include <stdlib.h>
#include <machine/param.h> /* for PAGE_SIZE */
#include <assert.h>
#include <setjmp.h>
#include <stdio.h>
#if defined(__i386__)
#define SET_STACK_JB(jb, stk) (jb)[0]._jb[2] = (int)(stk)
#define GET_STACK_JB(jb) ((unsigned long)((jb)[0]._jb[2]))
#define SET_RETURN_ADDR_JB(jb, ra) (jb)[0]._jb[0] = (int)(ra)
#elif defined(__alpha__)
#include <machine/reg.h>
#define SET_STACK_JB(jb, stk) (jb)[0]._jb[R_SP + 4] = (long)(stk)
#define GET_STACK_JB(jb) ((unsigned long)((jb)[0]._jb[R_SP + 4]))
#define SET_RETURN_ADDR_JB(jb, ra) do { \
(jb)[0]._jb[2] = (unsigned long)(ra) + 8UL; \
(jb)[0]._jb[R_RA + 4] = 0; \
(jb)[0]._jb[R_T12 + 4] = (long)(ra); \
} while (0)
#else
#error "Don't recognize this architecture!"
#endif
static jmp_buf retjb;
static jmp_buf schedjb;
static void
dump_jmpbuf(jmp_buf jb)
{
long *larr = (long *)jb[0]._jb;
int i;
for (i = 0; i < (sizeof(jmp_buf) / sizeof(long)); i++) {
printf(" 0x%lx\n", larr[i]);
}
}
static void
scheduler()
{
int tmp;
printf("Entered scheduler, stack is %p\n", &tmp);
_longjmp(retjb, 1);
}
int
main(int argc, char *argv[])
{
long schedstack;
long stacktop;
int i;
/* Create a stack for the scheduler: */
assert((schedstack = (long)malloc (PAGE_SIZE)) != NULL);
/* Stack starts high and grows up/low: */
stacktop = schedstack + PAGE_SIZE - sizeof (double);
/* Initialize the context for the scheduler: */
_setjmp(schedjb);
printf("Scheduler jmp_buf after _setjmp:\n");
dump_jmpbuf(schedjb);
SET_STACK_JB(schedjb, stacktop);
SET_RETURN_ADDR_JB(schedjb, scheduler);
printf("\nScheduler jmp_buf after tamporing:\n");
dump_jmpbuf(schedjb);
printf("\n");
for (i = 0; i < 10; i++) {
if (_setjmp(retjb) == 0) {
printf("Switching to scheduler, count %d.\n", i);
_longjmp(schedjb, 1);
}
}
return (0);
}
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