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[Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on
From: |
Brad Smith |
Subject: |
[Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD |
Date: |
Sun, 7 Oct 2018 11:37:31 -0400 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
Use MAP_STACK in qemu_alloc_stack() on OpenBSD.
Added to -current and will be in our soon to be 6.4 release.
MAP_STACK Indicate that the mapping is used as a stack. This
flag must be used in combination with MAP_ANON and
MAP_PRIVATE.
Implement MAP_STACK option for mmap(). Synchronous faults (pagefault and
syscall) confirm the stack register points at MAP_STACK memory, otherwise
SIGSEGV is delivered. sigaltstack() and pthread_attr_setstack() are modified
to create a MAP_STACK sub-region which satisfies alignment requirements.
Observe that MAP_STACK can only be set/cleared by mmap(), which zeroes the
contents of the region -- there is no mprotect() equivalent operation, so
there is no MAP_STACK-adding gadget.
Signed-off-by: Brad Smith <address@hidden>
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index fbd0dc8c57..51e9a012c2 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -611,7 +611,11 @@ void *qemu_alloc_stack(size_t *sz)
*sz += pagesz;
ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE,
- MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ MAP_PRIVATE | MAP_ANONYMOUS
+#ifdef MAP_STACK
+ | MAP_STACK
+#endif
+ , -1, 0);
if (ptr == MAP_FAILED) {
perror("failed to allocate memory for stack");
abort();
- [Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD,
Brad Smith <=
- Re: [Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD, Kamil Rytarowski, 2018/10/09
- Re: [Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD, Peter Maydell, 2018/10/09
- Re: [Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD, Kamil Rytarowski, 2018/10/09
- Re: [Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD, Brad Smith, 2018/10/10
- Re: [Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD, Peter Maydell, 2018/10/11
- Re: [Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD, Kamil Rytarowski, 2018/10/11
- Re: [Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD, Brad Smith, 2018/10/11
- Re: [Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD, Kamil Rytarowski, 2018/10/11
- Re: [Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD, Brad Smith, 2018/10/11
- Re: [Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD, Kamil Rytarowski, 2018/10/13