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bsd-user: Allocate guest virtual address space

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With reserved_va, mmap.c expects to have pre-allocated host address
space for the entire guest address space.  When combined with the -B
command-line option, ensure that the chosen address does not overlap
anything else.  Ensure that mmap_next_start is within reserved_va,
as we use it within mmap.c without checking.

Reviewed by: Warner Losh <imp@bsdimp.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230727161148.444988-1-richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2023-07-27 09:11:48 -07:00
parent ad17868eb1
commit 28b61d49ac
1 changed files with 43 additions and 5 deletions
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48
bsd-user/main.c
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@ -473,10 +473,6 @@ int main(int argc, char **argv)
target_environ = envlist_to_environ(envlist, NULL);
envlist_free(envlist);
if (reserved_va) {
mmap_next_start = reserved_va + 1;
}
{
Error *err = NULL;
if (seed_optarg != NULL) {
@ -494,7 +490,49 @@ int main(int argc, char **argv)
* Now that page sizes are configured we can do
* proper page alignment for guest_base.
*/
guest_base = HOST_PAGE_ALIGN(guest_base);
if (have_guest_base) {
if (guest_base & ~qemu_host_page_mask) {
error_report("Selected guest base not host page aligned");
exit(1);
}
}
/*
* If reserving host virtual address space, do so now.
* Combined with '-B', ensure that the chosen range is free.
*/
if (reserved_va) {
void *p;
if (have_guest_base) {
p = mmap((void *)guest_base, reserved_va + 1, PROT_NONE,
MAP_ANON | MAP_PRIVATE | MAP_FIXED | MAP_EXCL, -1, 0);
} else {
p = mmap(NULL, reserved_va + 1, PROT_NONE,
MAP_ANON | MAP_PRIVATE, -1, 0);
}
if (p == MAP_FAILED) {
const char *err = strerror(errno);
char *sz = size_to_str(reserved_va + 1);
if (have_guest_base) {
error_report("Cannot allocate %s bytes at -B %p for guest "
"address space: %s", sz, (void *)guest_base, err);
} else {
error_report("Cannot allocate %s bytes for guest "
"address space: %s", sz, err);
}
exit(1);
}
guest_base = (uintptr_t)p;
have_guest_base = true;
/* Ensure that mmap_next_start is within range. */
if (reserved_va <= mmap_next_start) {
mmap_next_start = (reserved_va / 4 * 3)
& TARGET_PAGE_MASK & qemu_host_page_mask;
}
}
if (loader_exec(filename, argv + optind, target_environ, regs, info,
&bprm) != 0) {