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Pre-allocate guest address space

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Allow pre-allocation of the guest virtual address space in usermode emulation.

Signed-off-by: Paul Brook <paul@codesourcery.com>
This commit is contained in:
Paul Brook 2010-05-29 02:27:35 +01:00
parent 0be1d07c0e
commit 68a1c81686
5 changed files with 183 additions and 8 deletions
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63
linux-user/main.c
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@ -44,6 +44,7 @@ unsigned long mmap_min_addr;
#if defined(CONFIG_USE_GUEST_BASE)
unsigned long guest_base;
int have_guest_base;
unsigned long reserved_va;
#endif
static const char *interp_prefix = CONFIG_QEMU_PREFIX;
@ -2610,6 +2611,7 @@ static void usage(void)
"-0 argv0 forces target process argv[0] to be argv0\n"
#if defined(CONFIG_USE_GUEST_BASE)
"-B address set guest_base address to address\n"
"-R size reserve size bytes for guest virtual address space\n"
#endif
"\n"
"Debug options:\n"
@ -2805,6 +2807,39 @@ int main(int argc, char **argv, char **envp)
} else if (!strcmp(r, "B")) {
guest_base = strtol(argv[optind++], NULL, 0);
have_guest_base = 1;
} else if (!strcmp(r, "R")) {
char *p;
int shift = 0;
reserved_va = strtoul(argv[optind++], &p, 0);
switch (*p) {
case 'k':
case 'K':
shift = 10;
break;
case 'M':
shift = 20;
break;
case 'G':
shift = 30;
break;
}
if (shift) {
unsigned long unshifted = reserved_va;
p++;
reserved_va <<= shift;
if (((reserved_va >> shift) != unshifted)
#if HOST_LONG_BITS > TARGET_VIRT_ADDR_SPACE_BITS
|| (reserved_va > (1ul << TARGET_VIRT_ADDR_SPACE_BITS))
#endif
) {
fprintf(stderr, "Reserved virtual address too big\n");
exit(1);
}
}
if (*p) {
fprintf(stderr, "Unrecognised -R size suffix '%s'\n", p);
exit(1);
}
#endif
} else if (!strcmp(r, "drop-ld-preload")) {
(void) envlist_unsetenv(envlist, "LD_PRELOAD");
@ -2893,6 +2928,34 @@ int main(int argc, char **argv, char **envp)
* proper page alignment for guest_base.
*/
guest_base = HOST_PAGE_ALIGN(guest_base);
if (reserved_va) {
void *p;
int flags;
flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE;
if (have_guest_base) {
flags |= MAP_FIXED;
}
p = mmap((void *)guest_base, reserved_va, PROT_NONE, flags, -1, 0);
if (p == MAP_FAILED) {
fprintf(stderr, "Unable to reserve guest address space\n");
exit(1);
}
guest_base = (unsigned long)p;
/* Make sure the address is properly aligned. */
if (guest_base & ~qemu_host_page_mask) {
munmap(p, reserved_va);
p = mmap((void *)guest_base, reserved_va + qemu_host_page_size,
PROT_NONE, flags, -1, 0);
if (p == MAP_FAILED) {
fprintf(stderr, "Unable to reserve guest address space\n");
exit(1);
}
guest_base = HOST_PAGE_ALIGN((unsigned long)p);
}
qemu_log("Reserved 0x%lx bytes of guest address space\n", reserved_va);
}
#endif /* CONFIG_USE_GUEST_BASE */
/*