From: "Alex Bennée" <alex.bennee@linaro.org>
To: qemu-devel@nongnu.org
Cc: fam@euphon.net, berrange@redhat.com,
"Alex Bennée" <alex.bennee@linaro.org>,
richard.henderson@linaro.org, f4bug@amsat.org,
"Laurent Vivier" <laurent@vivier.eu>,
cota@braap.org, aurelien@aurel32.net
Subject: [PATCH v2 08/12] linux-user: don't use MAP_FIXED in pgd_find_hole_fallback
Date: Wed, 22 Jul 2020 07:28:58 +0100 [thread overview]
Message-ID: <20200722062902.24509-9-alex.bennee@linaro.org> (raw)
In-Reply-To: <20200722062902.24509-1-alex.bennee@linaro.org>
Plain MAP_FIXED has the undesirable behaviour of splatting exiting
maps so we don't actually achieve what we want when looking for gaps.
We should be using MAP_FIXED_NOREPLACE. As this isn't always available
we need to potentially check the returned address to see if the kernel
gave us what we asked for.
Fixes: ad592e3
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
include/qemu/osdep.h | 3 +++
linux-user/elfload.c | 10 ++++++----
2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index e44547fb33e..4f8b95619ef 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -173,6 +173,9 @@ extern int daemon(int, int);
#ifndef MAP_ANONYMOUS
#define MAP_ANONYMOUS MAP_ANON
#endif
+#ifndef MAP_FIXED_NOREPLACE
+#define MAP_FIXED_NOREPLACE 0
+#endif
#ifndef ENOMEDIUM
#define ENOMEDIUM ENODEV
#endif
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 7e7f642332d..fe9dfe795dd 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2134,12 +2134,15 @@ static uintptr_t pgd_find_hole_fallback(uintptr_t guest_size, uintptr_t brk,
/* we have run out of space */
return -1;
} else {
- int flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE | MAP_FIXED;
+ int flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE |
+ MAP_FIXED_NOREPLACE;
void * mmap_start = mmap((void *) align_start, guest_size,
PROT_NONE, flags, -1, 0);
if (mmap_start != MAP_FAILED) {
munmap((void *) align_start, guest_size);
- return (uintptr_t) mmap_start + offset;
+ if (MAP_FIXED_NOREPLACE || mmap_start == (void *) align_start) {
+ return (uintptr_t) mmap_start + offset;
+ }
}
base += qemu_host_page_size;
}
@@ -2307,9 +2310,8 @@ static void pgb_reserved_va(const char *image_name, abi_ulong guest_loaddr,
/* Widen the "image" to the entire reserved address space. */
pgb_static(image_name, 0, reserved_va, align);
-#ifdef MAP_FIXED_NOREPLACE
+ /* osdep.h defines this as 0 if it's missing */
flags |= MAP_FIXED_NOREPLACE;
-#endif
/* Reserve the memory on the host. */
assert(guest_base != 0);
--
2.20.1
next prev parent reply other threads:[~2020-07-22 6:32 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-22 6:28 [PATCH v2 00/12] candidate fixes for 5.1-rc1 (testing, semihosting, OOM tcg, x86 fpu) Alex Bennée
2020-07-22 6:28 ` [PATCH v2 01/12] shippable: add one more qemu to registry url Alex Bennée
2020-07-22 6:28 ` [PATCH v2 02/12] semihosting: defer connect_chardevs a little more to use serialx Alex Bennée
2020-07-22 6:28 ` [PATCH v2 03/12] semihosting: don't send the trailing '\0' Alex Bennée
2020-07-22 6:28 ` [PATCH v2 04/12] util: add qemu_get_host_physmem utility function Alex Bennée
2020-07-22 15:51 ` Richard Henderson
2020-07-22 6:28 ` [PATCH v2 05/12] util/oslib-win32: add qemu_get_host_physmem implementation Alex Bennée
2020-07-22 6:49 ` Philippe Mathieu-Daudé
2020-07-22 10:03 ` Stefan Weil
2020-07-22 10:13 ` Daniel P. Berrangé
2020-07-22 11:33 ` Alex Bennée
2020-07-22 11:38 ` Daniel P. Berrangé
2020-07-22 10:32 ` 罗勇刚(Yonggang Luo)
2020-07-22 10:50 ` Stefan Weil
2020-07-22 11:31 ` Alex Bennée
2020-07-22 11:41 ` Daniel P. Berrangé
2020-07-22 6:28 ` [PATCH v2 06/12] accel/tcg: better handle memory constrained systems Alex Bennée
2020-07-22 15:57 ` Richard Henderson
2020-07-22 16:29 ` Alex Bennée
2020-07-22 16:44 ` Daniel P. Berrangé
2020-07-22 19:02 ` Richard Henderson
2020-07-23 9:00 ` Daniel P. Berrangé
2020-07-23 9:22 ` Alex Bennée
2020-07-23 9:31 ` Daniel P. Berrangé
2020-07-23 10:06 ` Alex Bennée
2020-07-22 6:28 ` [PATCH v2 07/12] target/i386: floatx80: avoid compound literals in static initializers Alex Bennée
2020-07-22 6:45 ` Philippe Mathieu-Daudé
2020-07-22 6:28 ` Alex Bennée [this message]
2020-07-22 16:00 ` [PATCH v2 08/12] linux-user: don't use MAP_FIXED in pgd_find_hole_fallback Richard Henderson
2020-07-22 6:28 ` [PATCH v2 09/12] tests/docker: fix update command due to python3 str/bytes distinction Alex Bennée
2020-07-22 6:29 ` [PATCH v2 10/12] tests/docker: fix binfmt_misc image building Alex Bennée
2020-07-22 6:35 ` Philippe Mathieu-Daudé
2020-07-22 6:29 ` [PATCH v2 11/12] tests/docker: add support for DEB_KEYRING Alex Bennée
2020-07-22 14:27 ` Philippe Mathieu-Daudé
2020-07-22 16:03 ` Richard Henderson
2020-07-22 6:29 ` [PATCH v2 12/12] linux-user: fix clock_nanosleep() Alex Bennée
2020-07-22 6:49 ` Laurent Vivier
2020-07-22 8:33 ` Laurent Vivier
2020-07-22 8:55 ` Alex Bennée
2020-07-22 12:03 ` Laurent Vivier
2020-07-22 7:05 ` Philippe Mathieu-Daudé
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