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[PATCH v7 02/31] linux-user: Introduce PAGE_ANON
From: |
Richard Henderson |
Subject: |
[PATCH v7 02/31] linux-user: Introduce PAGE_ANON |
Date: |
Fri, 12 Feb 2021 10:48:33 -0800 |
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>
---
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 af555f1798..1f47e0fe44 100644
--- a/include/exec/cpu-all.h
+++ b/include/exec/cpu-all.h
@@ -275,6 +275,8 @@ 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 c693505b60..7fb4c628e1 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:
--
2.25.1
- [PATCH v7 00/31] target-arm: Implement ARMv8.5-MemTag, user mode, Richard Henderson, 2021/02/12
- [PATCH v7 01/31] tcg: Introduce target-specific page data for user-only, Richard Henderson, 2021/02/12
- [PATCH v7 02/31] linux-user: Introduce PAGE_ANON,
Richard Henderson <=
- [PATCH v7 03/31] exec: Use uintptr_t for guest_base, Richard Henderson, 2021/02/12
- [PATCH v7 05/31] exec: Improve types for guest_addr_valid, Richard Henderson, 2021/02/12
- [PATCH v7 04/31] exec: Use uintptr_t in cpu_ldst.h, Richard Henderson, 2021/02/12
- [PATCH v7 08/31] bsd-user: Tidy VERIFY_READ/VERIFY_WRITE, Richard Henderson, 2021/02/12
- [PATCH v7 13/31] linux-user: Explicitly untag memory management syscalls, Richard Henderson, 2021/02/12
- [PATCH v7 09/31] linux-user: Do not use guest_addr_valid for h2g_valid, Richard Henderson, 2021/02/12
- [PATCH v7 07/31] linux-user: Tidy VERIFY_READ/VERIFY_WRITE, Richard Henderson, 2021/02/12