From 892a4f6a750abceeda4c1ee8324f58f82fd6bd89 Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Tue, 21 Jun 2022 16:42:05 +0200 Subject: 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 The PAGE_MAP_ANONYMOUS bits are superseded by commit 26bab757d41b ("linux-user: Introduce PAGE_ANON").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 Reviewed-by: Laurent Vivier Message-Id: <20220621144205.158452-1-iii@linux.ibm.com> Signed-off-by: Laurent Vivier --- linux-user/user-internals.h | 1 + 1 file changed, 1 insertion(+) (limited to 'linux-user/user-internals.h') 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); -- cgit 1.4.1