include/exec: Change reserved_va semantics to last byte
Change the semantics to be the last byte of the guest va, rather
than the following byte. This avoids some overflow conditions.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/bsd-user/main.c b/bsd-user/main.c
index 89f225d..babc3b0 100644
--- a/bsd-user/main.c
+++ b/bsd-user/main.c
@@ -68,13 +68,9 @@
# if HOST_LONG_BITS > TARGET_VIRT_ADDR_SPACE_BITS
# if TARGET_VIRT_ADDR_SPACE_BITS == 32 && \
(TARGET_LONG_BITS == 32 || defined(TARGET_ABI32))
-/*
- * There are a number of places where we assign reserved_va to a variable
- * of type abi_ulong and expect it to fit. Avoid the last page.
- */
-# define MAX_RESERVED_VA (0xfffffffful & TARGET_PAGE_MASK)
+# define MAX_RESERVED_VA 0xfffffffful
# else
-# define MAX_RESERVED_VA (1ul << TARGET_VIRT_ADDR_SPACE_BITS)
+# define MAX_RESERVED_VA ((1ul << TARGET_VIRT_ADDR_SPACE_BITS) - 1)
# endif
# else
# define MAX_RESERVED_VA 0
@@ -466,7 +462,7 @@
envlist_free(envlist);
if (reserved_va) {
- mmap_next_start = reserved_va;
+ mmap_next_start = reserved_va + 1;
}
{
diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c
index 6960575..565b9f9 100644
--- a/bsd-user/mmap.c
+++ b/bsd-user/mmap.c
@@ -234,7 +234,7 @@
size = HOST_PAGE_ALIGN(size) + alignment;
end_addr = start + size;
if (end_addr > reserved_va) {
- end_addr = reserved_va;
+ end_addr = reserved_va + 1;
}
addr = end_addr - qemu_host_page_size;
@@ -243,7 +243,7 @@
if (looped) {
return (abi_ulong)-1;
}
- end_addr = reserved_va;
+ end_addr = reserved_va + 1;
addr = end_addr - qemu_host_page_size;
looped = 1;
continue;
diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
index 64cb62d..090922e 100644
--- a/include/exec/cpu-all.h
+++ b/include/exec/cpu-all.h
@@ -152,6 +152,15 @@
*/
extern uintptr_t guest_base;
extern bool have_guest_base;
+
+/*
+ * If non-zero, the guest virtual address space is a contiguous subset
+ * of the host virtual address space, i.e. '-R reserved_va' is in effect
+ * either from the command-line or by default. The value is the last
+ * byte of the guest address space e.g. UINT32_MAX.
+ *
+ * If zero, the host and guest virtual address spaces are intermingled.
+ */
extern unsigned long reserved_va;
/*
@@ -171,7 +180,7 @@
#define GUEST_ADDR_MAX_ \
((MIN_CONST(TARGET_VIRT_ADDR_SPACE_BITS, TARGET_ABI_BITS) <= 32) ? \
UINT32_MAX : ~0ul)
-#define GUEST_ADDR_MAX (reserved_va ? reserved_va - 1 : GUEST_ADDR_MAX_)
+#define GUEST_ADDR_MAX (reserved_va ? : GUEST_ADDR_MAX_)
#else
diff --git a/linux-user/arm/target_cpu.h b/linux-user/arm/target_cpu.h
index 89ba274..f6383a7 100644
--- a/linux-user/arm/target_cpu.h
+++ b/linux-user/arm/target_cpu.h
@@ -30,7 +30,7 @@
* the high addresses. Restrict linux-user to the
* cached write-back RAM in the system map.
*/
- return 0x80000000ul;
+ return 0x7ffffffful;
} else {
/*
* We need to be able to map the commpage.
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index dfae967..f1370a7 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -208,7 +208,7 @@
* has specified -R reserved_va, which would trigger an assert().
*/
if (reserved_va != 0 &&
- TARGET_VSYSCALL_PAGE + TARGET_PAGE_SIZE >= reserved_va) {
+ TARGET_VSYSCALL_PAGE + TARGET_PAGE_SIZE - 1 > reserved_va) {
error_report("Cannot allocate vsyscall page");
exit(EXIT_FAILURE);
}
@@ -2504,7 +2504,7 @@
if (guest_hiaddr > reserved_va) {
error_report("%s: requires more than reserved virtual "
"address space (0x%" PRIx64 " > 0x%lx)",
- image_name, (uint64_t)guest_hiaddr + 1, reserved_va);
+ image_name, (uint64_t)guest_hiaddr, reserved_va);
exit(EXIT_FAILURE);
}
} else {
@@ -2525,7 +2525,7 @@
if (reserved_va) {
guest_loaddr = (guest_base >= mmap_min_addr ? 0
: mmap_min_addr - guest_base);
- guest_hiaddr = reserved_va - 1;
+ guest_hiaddr = reserved_va;
}
/* Reserve the address space for the binary, or reserved_va. */
@@ -2755,7 +2755,7 @@
if (guest_hiaddr > reserved_va) {
error_report("%s: requires more than reserved virtual "
"address space (0x%" PRIx64 " > 0x%lx)",
- image_name, (uint64_t)guest_hiaddr + 1, reserved_va);
+ image_name, (uint64_t)guest_hiaddr, reserved_va);
exit(EXIT_FAILURE);
}
@@ -2768,17 +2768,17 @@
/* Reserve the memory on the host. */
assert(guest_base != 0);
test = g2h_untagged(0);
- addr = mmap(test, reserved_va, PROT_NONE, flags, -1, 0);
+ addr = mmap(test, reserved_va + 1, PROT_NONE, flags, -1, 0);
if (addr == MAP_FAILED || addr != test) {
error_report("Unable to reserve 0x%lx bytes of virtual address "
"space at %p (%s) for use as guest address space (check your "
"virtual memory ulimit setting, min_mmap_addr or reserve less "
- "using -R option)", reserved_va, test, strerror(errno));
+ "using -R option)", reserved_va + 1, test, strerror(errno));
exit(EXIT_FAILURE);
}
qemu_log_mask(CPU_LOG_PAGE, "%s: base @ %p for %lu bytes\n",
- __func__, addr, reserved_va);
+ __func__, addr, reserved_va + 1);
}
void probe_guest_base(const char *image_name, abi_ulong guest_loaddr,
diff --git a/linux-user/main.c b/linux-user/main.c
index 39d9bd4..fe03293 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -109,11 +109,9 @@
# if HOST_LONG_BITS > TARGET_VIRT_ADDR_SPACE_BITS
# if TARGET_VIRT_ADDR_SPACE_BITS == 32 && \
(TARGET_LONG_BITS == 32 || defined(TARGET_ABI32))
-/* There are a number of places where we assign reserved_va to a variable
- of type abi_ulong and expect it to fit. Avoid the last page. */
-# define MAX_RESERVED_VA(CPU) (0xfffffffful & TARGET_PAGE_MASK)
+# define MAX_RESERVED_VA(CPU) 0xfffffffful
# else
-# define MAX_RESERVED_VA(CPU) (1ul << TARGET_VIRT_ADDR_SPACE_BITS)
+# define MAX_RESERVED_VA(CPU) ((1ul << TARGET_VIRT_ADDR_SPACE_BITS) - 1)
# endif
# else
# define MAX_RESERVED_VA(CPU) 0
@@ -379,7 +377,9 @@
{
char *p;
int shift = 0;
- reserved_va = strtoul(arg, &p, 0);
+ unsigned long val;
+
+ val = strtoul(arg, &p, 0);
switch (*p) {
case 'k':
case 'K':
@@ -393,10 +393,10 @@
break;
}
if (shift) {
- unsigned long unshifted = reserved_va;
+ unsigned long unshifted = val;
p++;
- reserved_va <<= shift;
- if (reserved_va >> shift != unshifted) {
+ val <<= shift;
+ if (val >> shift != unshifted) {
fprintf(stderr, "Reserved virtual address too big\n");
exit(EXIT_FAILURE);
}
@@ -405,6 +405,8 @@
fprintf(stderr, "Unrecognised -R size suffix '%s'\n", p);
exit(EXIT_FAILURE);
}
+ /* The representation is size - 1, with 0 remaining "default". */
+ reserved_va = val ? val - 1 : 0;
}
static void handle_arg_singlestep(const char *arg)
@@ -793,7 +795,7 @@
*/
max_reserved_va = MAX_RESERVED_VA(cpu);
if (reserved_va != 0) {
- if (reserved_va % qemu_host_page_size) {
+ if ((reserved_va + 1) % qemu_host_page_size) {
char *s = size_to_str(qemu_host_page_size);
fprintf(stderr, "Reserved virtual address not aligned mod %s\n", s);
g_free(s);
@@ -804,11 +806,8 @@
exit(EXIT_FAILURE);
}
} else if (HOST_LONG_BITS == 64 && TARGET_VIRT_ADDR_SPACE_BITS <= 32) {
- /*
- * reserved_va must be aligned with the host page size
- * as it is used with mmap()
- */
- reserved_va = max_reserved_va & qemu_host_page_mask;
+ /* MAX_RESERVED_VA + 1 is a large power of 2, so is aligned. */
+ reserved_va = max_reserved_va;
}
{
diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 995146f..0aa8ae7 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -283,7 +283,7 @@
end_addr = start + size;
if (start > reserved_va - size) {
/* Start at the top of the address space. */
- end_addr = ((reserved_va - size) & -align) + size;
+ end_addr = ((reserved_va + 1 - size) & -align) + size;
looped = true;
}
@@ -297,7 +297,7 @@
return (abi_ulong)-1;
}
/* Re-start at the top of the address space. */
- addr = end_addr = ((reserved_va - size) & -align) + size;
+ addr = end_addr = ((reserved_va + 1 - size) & -align) + size;
looped = true;
} else {
prot = page_get_flags(addr);
