Commit 6fe7a5bba7 for qemu.org
commit 6fe7a5bba780196f52956dc976744b37f529ad17
Author: Richard Henderson <richard.henderson@linaro.org>
Date: Fri May 29 16:10:15 2026 -0700
linux-user: Use PGBRange for commpage
This simplifies check for no commpage to a NULL pointer
check, rather than reserved values for LO_COMMPAGE and
HI_COMMPAGE.
Unify {LO,HI}_COMMPAGE into a single COMMPAGE define.
Acked-by: Warner Losh <imp@bsdimp.com>
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/linux-user/arm/elfload.c b/linux-user/arm/elfload.c
index 13b589ea2c..ce69bf0542 100644
--- a/linux-user/arm/elfload.c
+++ b/linux-user/arm/elfload.c
@@ -220,7 +220,7 @@ bool init_guest_commpage(void)
return true;
}
- commpage = HI_COMMPAGE & -host_page_size;
+ commpage = COMMPAGE & -host_page_size;
want = g2h_untagged(commpage);
addr = mmap(want, host_page_size, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE |
diff --git a/linux-user/arm/target_elf.h b/linux-user/arm/target_elf.h
index 12cdc8e5a7..531b486bf9 100644
--- a/linux-user/arm/target_elf.h
+++ b/linux-user/arm/target_elf.h
@@ -20,7 +20,7 @@
#define HAVE_ELF_CORE_DUMP 1
#define HAVE_VDSO_IMAGE_INFO 1
-#define HI_COMMPAGE ((intptr_t)0xffff0f00u)
+#define COMMPAGE ((intptr_t)0xffff0f00u)
/*
* See linux kernel: arch/arm/include/asm/elf.h, where
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 19d2bad581..557ed20dbf 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -757,17 +757,9 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
return sp;
}
-#if defined(HI_COMMPAGE)
-#define LO_COMMPAGE -1
-#elif defined(LO_COMMPAGE)
-#define HI_COMMPAGE 0
-#else
-#define HI_COMMPAGE 0
-#define LO_COMMPAGE -1
-#ifndef HAVE_GUEST_COMMPAGE
+#if !defined(COMMPAGE) && !defined(HAVE_GUEST_COMMPAGE)
bool init_guest_commpage(void) { return true; }
#endif
-#endif
/**
* pgb_try_mmap:
@@ -853,7 +845,7 @@ static bool pgb_try_mmap_set(const PGBAddrs *ga, uintptr_t base, uintptr_t brk)
* Fill in @ga with the image, COMMPAGE and NULL page.
*/
static bool pgb_addr_set(PGBAddrs *ga, const PGBRange *image_range,
- bool try_identity)
+ const PGBRange *commpage_range, bool try_identity)
{
int n;
@@ -862,7 +854,7 @@ static bool pgb_addr_set(PGBAddrs *ga, const PGBRange *image_range,
* we may not be able to use the identity map.
*/
if (try_identity) {
- if (LO_COMMPAGE != -1 && LO_COMMPAGE < mmap_min_addr) {
+ if (commpage_range && commpage_range->lo < mmap_min_addr) {
return false;
}
if (image_range && image_range->lo < mmap_min_addr) {
@@ -877,14 +869,10 @@ static bool pgb_addr_set(PGBAddrs *ga, const PGBRange *image_range,
ga->bounds[n].lo = try_identity ? mmap_min_addr : 0;
ga->bounds[n].hi = reserved_va;
n++;
- /* LO_COMMPAGE and NULL handled by reserving from 0. */
+ /* Low COMMPAGE and NULL handled by reserving from 0. */
} else {
- /* Add any LO_COMMPAGE or NULL page. */
- if (LO_COMMPAGE != -1) {
- ga->bounds[n].lo = 0;
- ga->bounds[n].hi = LO_COMMPAGE + TARGET_PAGE_SIZE - 1;
- n++;
- } else if (!try_identity) {
+ /* Add any low COMMPAGE or NULL page. */
+ if (!try_identity || (commpage_range && commpage_range->lo == 0)) {
ga->bounds[n].lo = 0;
ga->bounds[n].hi = TARGET_PAGE_SIZE - 1;
n++;
@@ -896,23 +884,13 @@ static bool pgb_addr_set(PGBAddrs *ga, const PGBRange *image_range,
}
}
- /*
- * Temporarily disable
- * "comparison is always false due to limited range of data type"
- * due to comparison between unsigned and (possible) 0.
- */
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wtype-limits"
-
- /* Add any HI_COMMPAGE not covered by reserved_va. */
- if (reserved_va < HI_COMMPAGE) {
- ga->bounds[n].lo = HI_COMMPAGE & qemu_real_host_page_mask();
- ga->bounds[n].hi = HI_COMMPAGE + TARGET_PAGE_SIZE - 1;
+ /* Add any high COMMPAGE not covered by reserved_va. */
+ if (commpage_range && reserved_va < commpage_range->hi) {
+ ga->bounds[n].lo = commpage_range->lo & qemu_real_host_page_mask();
+ ga->bounds[n].hi = commpage_range->hi;
n++;
}
-#pragma GCC diagnostic pop
-
ga->nbounds = n;
return true;
}
@@ -926,7 +904,7 @@ static void pgb_fail_in_use(const char *image_name)
}
static void pgb_fixed(const char *image_name, const PGBRange *image_range,
- uintptr_t align)
+ const PGBRange *commpage_range, uintptr_t align)
{
PGBAddrs ga;
uintptr_t brk = (uintptr_t)sbrk(0);
@@ -938,7 +916,7 @@ static void pgb_fixed(const char *image_name, const PGBRange *image_range,
exit(EXIT_FAILURE);
}
- if (!pgb_addr_set(&ga, image_range, !guest_base)
+ if (!pgb_addr_set(&ga, image_range, commpage_range, !guest_base)
|| !pgb_try_mmap_set(&ga, guest_base, brk)) {
pgb_fail_in_use(image_name);
}
@@ -1024,14 +1002,14 @@ static uintptr_t pgb_find_itree(const PGBAddrs *ga, IntervalTreeRoot *root,
}
static void pgb_dynamic(const char *image_name, const PGBRange *image_range,
- uintptr_t align)
+ const PGBRange *commpage_range, uintptr_t align)
{
IntervalTreeRoot *root;
uintptr_t brk, ret;
PGBAddrs ga;
/* Try the identity map first. */
- if (pgb_addr_set(&ga, image_range, true)) {
+ if (pgb_addr_set(&ga, image_range, commpage_range, true)) {
brk = (uintptr_t)sbrk(0);
if (pgb_try_mmap_set(&ga, 0, brk)) {
guest_base = 0;
@@ -1043,7 +1021,7 @@ static void pgb_dynamic(const char *image_name, const PGBRange *image_range,
* Rebuild the address set for non-identity map.
* This differs in the mapping of the guest NULL page.
*/
- pgb_addr_set(&ga, image_range, false);
+ pgb_addr_set(&ga, image_range, commpage_range, false);
root = read_self_maps();
@@ -1084,6 +1062,14 @@ static void pgb_dynamic(const char *image_name, const PGBRange *image_range,
void probe_guest_base(const char *image_name, const PGBRange *image_range)
{
+#ifdef COMMPAGE
+ const PGBRange * const commpage_range = &(PGBRange){
+ COMMPAGE, COMMPAGE + TARGET_PAGE_SIZE - 1
+ };
+#else
+ const PGBRange * const commpage_range = NULL;
+#endif
+
/* In order to use host shmat, we must be able to honor SHMLBA. */
uintptr_t align = MAX(SHMLBA, TARGET_PAGE_SIZE);
@@ -1096,9 +1082,9 @@ void probe_guest_base(const char *image_name, const PGBRange *image_range)
}
if (have_guest_base) {
- pgb_fixed(image_name, image_range, align);
+ pgb_fixed(image_name, image_range, commpage_range, align);
} else {
- pgb_dynamic(image_name, image_range, align);
+ pgb_dynamic(image_name, image_range, commpage_range, align);
}
/* Reserve and initialize the commpage. */
diff --git a/linux-user/hppa/elfload.c b/linux-user/hppa/elfload.c
index 2ebb9924f1..ff4301b2ed 100644
--- a/linux-user/hppa/elfload.c
+++ b/linux-user/hppa/elfload.c
@@ -36,7 +36,7 @@ bool init_guest_commpage(void)
if (!reserved_va) {
void *want, *addr;
- want = g2h_untagged(LO_COMMPAGE);
+ want = g2h_untagged(COMMPAGE);
addr = mmap(want, TARGET_PAGE_SIZE, PROT_NONE,
MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED_NOREPLACE, -1, 0);
if (addr == MAP_FAILED) {
@@ -55,7 +55,7 @@ bool init_guest_commpage(void)
* and implement syscalls. Here, simply mark the page executable.
* Special case the entry points during translation (see do_page_zero).
*/
- page_set_flags(LO_COMMPAGE, LO_COMMPAGE | ~TARGET_PAGE_MASK,
+ page_set_flags(COMMPAGE, COMMPAGE | ~TARGET_PAGE_MASK,
PAGE_EXEC | PAGE_VALID, PAGE_VALID);
return true;
}
diff --git a/linux-user/hppa/target_elf.h b/linux-user/hppa/target_elf.h
index e1c5033242..22547b1437 100644
--- a/linux-user/hppa/target_elf.h
+++ b/linux-user/hppa/target_elf.h
@@ -34,7 +34,7 @@ typedef struct target_elf_gregset_t {
abi_ulong pad[16]; /* pad to 80 elements [64..79] */
} target_elf_gregset_t;
-#define LO_COMMPAGE 0
+#define COMMPAGE 0
#define STACK_GROWS_DOWN 0
#define STACK_ALIGNMENT 64
#define VDSO_HEADER "vdso.c.inc"