[glibc] hurd: Stop relying on VM_MAX_ADDRESS

[glibc] hurd: Stop relying on VM_MAX_ADDRESS

[Samuel Thibault]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=4648bfbbde5466929d24013478697cbdec847b46

commit 4648bfbbde5466929d24013478697cbdec847b46
Author: Sergey Bugaev <bugaevc@gmail.com>
Date:   Sat Mar 23 20:32:43 2024 +0300

    hurd: Stop relying on VM_MAX_ADDRESS
    
    We'd like to avoid committing to a specific size of virtual address
    space (i.e. the value of VM_AARCH64_T0SZ) on AArch64.  While the current
    version of GNU Mach still exports VM_MAX_ADDRESS for compatibility, we
    should try to avoid relying on it when we can.  This piece of logic in
    _hurdsig_getenv () doesn't actually care about the size of user-
    accessible virtual address space, it just wants to preempt faults on any
    addresses starting from the value of the P pointer and above.  So, use
    (unsigned long int) -1 instead of VM_MAX_ADDRESS.
    
    While at it, change the casts to (unsigned long int) and not just
    (long int), since the type of struct hurd_signal_preemptor.{first,last}
    is unsigned long int.
    
    Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
    Message-ID: <20240323173301.151066-3-bugaevc@gmail.com>

Diff:
---
 hurd/hurdsig.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/hurd/hurdsig.c b/hurd/hurdsig.c
index 882a03471d..8b1928d1a1 100644
--- a/hurd/hurdsig.c
+++ b/hurd/hurdsig.c
@@ -1658,8 +1658,8 @@ _hurdsig_getenv (const char *variable)
       while (*ep)
 	{
 	  const char *p = *ep;
-	  _hurdsig_fault_preemptor.first = (long int) p;
-	  _hurdsig_fault_preemptor.last = VM_MAX_ADDRESS;
+	  _hurdsig_fault_preemptor.first = (unsigned long int) p;
+	  _hurdsig_fault_preemptor.last = (unsigned long int) -1;
 	  if (! strncmp (p, variable, len) && p[len] == '=')
 	    {
 	      size_t valuelen;
@@ -1671,8 +1671,8 @@ _hurdsig_getenv (const char *variable)
 		memcpy (value, p, valuelen);
 	      break;
 	    }
-	  _hurdsig_fault_preemptor.first = (long int) ++ep;
-	  _hurdsig_fault_preemptor.last = (long int) (ep + 1);
+	  _hurdsig_fault_preemptor.first = (unsigned long int) ++ep;
+	  _hurdsig_fault_preemptor.last = (unsigned long int) (ep + 1);
 	}
       _hurdsig_end_catch_fault ();
       return value;