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From: Samuel Thibault <sthibaul@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc] htl: Let Mach place thread stacks Date: Sun, 2 Jul 2023 23:38:24 +0000 (GMT) [thread overview] Message-ID: <20230702233824.24E813858412@sourceware.org> (raw) 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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