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* [glibc] htl: Let Mach place thread stacks
@ 2023-07-02 23:38 Samuel Thibault
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From: Samuel Thibault @ 2023-07-02 23:38 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=019b0bbc84e2048556ac1a6b6df3a61e45fc1e17
commit 019b0bbc84e2048556ac1a6b6df3a61e45fc1e17
Author: Sergey Bugaev <bugaevc@gmail.com>
Date: Mon Jun 26 02:17:47 2023 +0300
htl: Let Mach place thread stacks
Instead of trying to allocate a thread stack at a specific address,
looping over the address space, just set the ANYWHERE flag in
vm_allocate (). The previous behavior:
- defeats ASLR (for Mach versions that support ASLR),
- is particularly slow if the lower 4 GB of the address space are mapped
inaccessible, as we're planning to do on 64-bit Hurd,
- is just silly.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230625231751.404120-1-bugaevc@gmail.com>
Diff:
---
sysdeps/mach/htl/pt-stack-alloc.c | 35 ++++++-----------------------------
1 file changed, 6 insertions(+), 29 deletions(-)
diff --git a/sysdeps/mach/htl/pt-stack-alloc.c b/sysdeps/mach/htl/pt-stack-alloc.c
index 429ac2d9f7..97e6b4455b 100644
--- a/sysdeps/mach/htl/pt-stack-alloc.c
+++ b/sysdeps/mach/htl/pt-stack-alloc.c
@@ -19,14 +19,9 @@
#include <errno.h>
#include <mach.h>
-#include <mach/machine/vm_param.h>
#include <pt-internal.h>
-/* The next address to use for stack allocation. */
-static vm_address_t next_stack_base = VM_MIN_ADDRESS;
-
-
/* Allocate a new stack of size STACKSIZE. If successful, store the
address of the newly allocated stack in *STACKADDR and return 0.
Otherwise return an error code (EINVAL for an invalid stack size,
@@ -35,30 +30,12 @@ static vm_address_t next_stack_base = VM_MIN_ADDRESS;
int
__pthread_stack_alloc (void **stackaddr, size_t stacksize)
{
- vm_offset_t base;
- int i = 0;
-
-get_stack:
- i++;
- for (base = next_stack_base;
- base < VM_MAX_ADDRESS
- && __vm_allocate (__mach_task_self (), &base,
- stacksize, FALSE) != KERN_SUCCESS; base += stacksize)
- ;
-
- if (base >= VM_MAX_ADDRESS)
- {
- if (i == 1)
- {
- next_stack_base = VM_MIN_ADDRESS;
- goto get_stack;
- }
- else
- return EAGAIN;
- }
+ error_t err;
- next_stack_base = base + stacksize;
+ err = __vm_allocate (__mach_task_self (), (vm_offset_t *) stackaddr,
+ stacksize, TRUE);
- (*stackaddr) = (void *) base;
- return 0;
+ if (err == KERN_NO_SPACE)
+ err = EAGAIN;
+ return err;
}
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