diff options
| author | Ilya Leoshkevich <iii@linux.ibm.com> | 2022-06-21 16:42:05 +0200 |
|---|---|---|
| committer | Laurent Vivier <laurent@vivier.eu> | 2022-06-24 10:00:00 +0200 |
| commit | 892a4f6a750abceeda4c1ee8324f58f82fd6bd89 (patch) | |
| tree | e0653c18cff17f077638a38762d310072d649c7e /linux-user/user-internals.h | |
| parent | 9263ba847352c2ec2fc37ad7f7d0558332bd077f (diff) | |
linux-user: Add partial support for MADV_DONTNEED
Currently QEMU ignores madvise(MADV_DONTNEED), which break apps that
rely on this for zeroing out memory [1]. Improve the situation by doing
a passthrough when the range in question is a host-page-aligned
anonymous mapping.
This is based on the patches from Simon Hausmann [2] and Chris Fallin
[3]. The structure is taken from Simon's patch. The PAGE_MAP_ANONYMOUS
bits are superseded by commit 26bab757d41b ("linux-user: Introduce
PAGE_ANON"). In the end the patch acts like the one from Chris: we
either pass-through the entire syscall, or do nothing, since doing this
only partially would not help the affected applications much. Finally,
add some extra checks to match the behavior of the Linux kernel [4].
[1] https://gitlab.com/qemu-project/qemu/-/issues/326
[2] https://patchew.org/QEMU/20180827084037.25316-1-simon.hausmann@qt.io/
[3] https://github.com/bytecodealliance/wasmtime/blob/v0.37.0/ci/qemu-madvise.patch
[4] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/madvise.c?h=v5.19-rc3#n1368
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20220621144205.158452-1-iii@linux.ibm.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Diffstat (limited to 'linux-user/user-internals.h')
| -rw-r--r-- | linux-user/user-internals.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/linux-user/user-internals.h b/linux-user/user-internals.h index 6175ce53db..0280e76add 100644 --- a/linux-user/user-internals.h +++ b/linux-user/user-internals.h @@ -65,6 +65,7 @@ abi_long do_syscall(CPUArchState *cpu_env, int num, abi_long arg1, abi_long arg8); extern __thread CPUState *thread_cpu; G_NORETURN void cpu_loop(CPUArchState *env); +abi_long get_errno(abi_long ret); const char *target_strerror(int err); int get_osversion(void); void init_qemu_uname_release(void); |