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Some linux apps, such as IBM's JDK 1.3, will attempt to mmap thread

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stacks near the top of their address space.  If their TOS is greater
than vm_maxsaddr, vm_map_growstack() will confuse the thread stack
with the process stack and deliver a SEGV if they attempt to grow the
thread stack past their current stacksize rlimit.  To avoid this,
adjust vm_maxsaddr upwards to reflect the current stacksize rlimit
rather than the maximum possible stacksize.  It would be better to
adjust the mmap'ed region, but some apps (again, IBM's JDK 1.3) do not
check mmap's return value..

This commit (in conjunction with setting MINSIGSTKSZ to 2048 &
rebuilding your kernel and modules) will get IBM's JDK 1.3 working
with FreeBSD at least well enough to run many of the example applets.

Reviewed by: marcel
Tested by:   sto@stat.duke.edu, many others on freebsd-java@
This commit is contained in:
gallatin 2000-10-17 00:25:43 +00:00
parent 1b714c194a
commit 9e0a06f204
1 changed files with 28 additions and 0 deletions
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28
sys/i386/linux/linux_machdep.c
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@ -34,12 +34,20 @@
#include <sys/sysproto.h>
#include <sys/systm.h>
#include <sys/unistd.h>
#include <sys/resource.h>
#include <sys/resourcevar.h>
#include <machine/frame.h>
#include <machine/psl.h>
#include <machine/segments.h>
#include <machine/sysarch.h>
#include <vm/vm.h>
#include <sys/lock.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <i386/linux/linux.h>
#include <i386/linux/linux_proto.h>
#include <compat/linux/linux_ipc.h>
@ -341,6 +349,26 @@ linux_mmap(struct proc *p, struct linux_mmap_args *args)
/* This gives us TOS */
bsd_args.addr = linux_args.addr + linux_args.len;
if (bsd_args.addr > p->p_vmspace->vm_maxsaddr) {
/* Some linux apps will attempt to mmap
* thread stacks near the top of their
* address space. If their TOS is greater
* than vm_maxsaddr, vm_map_growstack()
* will confuse the thread stack with the
* process stack and deliver a SEGV if they
* attempt to grow the thread stack past their
* current stacksize rlimit. To avoid this,
* adjust vm_maxsaddr upwards to reflect
* the current stacksize rlimit rather
* than the maximum possible stacksize.
* It would be better to adjust the
* mmap'ed region, but some apps do not check
* mmap's return value.
*/
p->p_vmspace->vm_maxsaddr = (char *)USRSTACK -
p->p_rlimit[RLIMIT_STACK].rlim_cur;
}
/* This gives us our maximum stack size */
if (linux_args.len > STACK_SIZE - GUARD_SIZE)
bsd_args.len = linux_args.len;