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[PULL 02/40] linux-user: Introduce PAGE_ANON
From: |
Peter Maydell |
Subject: |
[PULL 02/40] linux-user: Introduce PAGE_ANON |
Date: |
Tue, 16 Feb 2021 16:16:20 +0000 |
From: Richard Henderson <richard.henderson@linaro.org>
Record whether the backing page is anonymous, or if it has file
backing. This will allow us to get close to the Linux AArch64
ABI for MTE, which allows tag memory only on ram-backed VMAs.
The real ABI allows tag memory on files, when those files are
on ram-backed filesystems, such as tmpfs. We will not be able
to implement that in QEMU linux-user.
Thankfully, anonymous memory for malloc arenas is the primary
consumer of this feature, so this restricted version should
still be of use.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210212184902.1251044-3-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
include/exec/cpu-all.h | 2 ++
linux-user/mmap.c | 3 +++
2 files changed, 5 insertions(+)
diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
index 6421892830c..aedf5345449 100644
--- a/include/exec/cpu-all.h
+++ b/include/exec/cpu-all.h
@@ -267,6 +267,8 @@ extern intptr_t qemu_host_page_mask;
#define PAGE_WRITE_INV 0x0020
/* For use with page_set_flags: page is being replaced; target_data cleared. */
#define PAGE_RESET 0x0040
+/* For linux-user, indicates that the page is MAP_ANON. */
+#define PAGE_ANON 0x0080
#if defined(CONFIG_BSD) && defined(CONFIG_USER_ONLY)
/* FIXME: Code that sets/uses this is broken and needs to go away. */
diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index ac0624f31ac..c52b60482e1 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -599,6 +599,9 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int
target_prot,
}
}
the_end1:
+ if (flags & MAP_ANONYMOUS) {
+ page_flags |= PAGE_ANON;
+ }
page_flags |= PAGE_RESET;
page_set_flags(start, start + len, page_flags);
the_end:
--
2.20.1
- [PULL 00/40] target-arm queue, Peter Maydell, 2021/02/16
- [PULL 01/40] tcg: Introduce target-specific page data for user-only, Peter Maydell, 2021/02/16
- [PULL 03/40] exec: Use uintptr_t for guest_base, Peter Maydell, 2021/02/16
- [PULL 04/40] exec: Use uintptr_t in cpu_ldst.h, Peter Maydell, 2021/02/16
- [PULL 02/40] linux-user: Introduce PAGE_ANON,
Peter Maydell <=
- [PULL 08/40] bsd-user: Tidy VERIFY_READ/VERIFY_WRITE, Peter Maydell, 2021/02/16
- [PULL 09/40] linux-user: Do not use guest_addr_valid for h2g_valid, Peter Maydell, 2021/02/16
- [PULL 05/40] exec: Improve types for guest_addr_valid, Peter Maydell, 2021/02/16
- [PULL 06/40] linux-user: Check for overflow in access_ok, Peter Maydell, 2021/02/16
- [PULL 10/40] linux-user: Fix guest_addr_valid vs reserved_va, Peter Maydell, 2021/02/16
- [PULL 07/40] linux-user: Tidy VERIFY_READ/VERIFY_WRITE, Peter Maydell, 2021/02/16
- [PULL 11/40] exec: Introduce cpu_untagged_addr, Peter Maydell, 2021/02/16
- [PULL 12/40] exec: Use cpu_untagged_addr in g2h; split out g2h_untagged, Peter Maydell, 2021/02/16
- [PULL 13/40] linux-user: Explicitly untag memory management syscalls, Peter Maydell, 2021/02/16
- [PULL 14/40] linux-user: Use guest_range_valid in access_ok, Peter Maydell, 2021/02/16