tcg: Introduce target-specific page data for user-only

This data can be allocated by page_alloc_target_data() and
released by page_set_flags(start, end, prot | PAGE_RESET).

This data will be used to hold tag memory for AArch64 MTE.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210212184902.1251044-2-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 36 insertions, 6 deletions

diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
index babf0a8959..6421892830 100644
--- a/include/exec/cpu-all.h
+++ b/include/exec/cpu-all.h
@@ -256,15 +256,21 @@ extern intptr_t qemu_host_page_mask;
 #define PAGE_EXEC      0x0004
 #define PAGE_BITS      (PAGE_READ | PAGE_WRITE | PAGE_EXEC)
 #define PAGE_VALID     0x0008
-/* original state of the write flag (used when tracking self-modifying
-   code */
+/*
+ * Original state of the write flag (used when tracking self-modifying code)
+ */
 #define PAGE_WRITE_ORG 0x0010
-/* Invalidate the TLB entry immediately, helpful for s390x
- * Low-Address-Protection. Used with PAGE_WRITE in tlb_set_page_with_attrs() */
-#define PAGE_WRITE_INV 0x0040
+/*
+ * Invalidate the TLB entry immediately, helpful for s390x
+ * Low-Address-Protection. Used with PAGE_WRITE in tlb_set_page_with_attrs()
+ */
+#define PAGE_WRITE_INV 0x0020
+/* For use with page_set_flags: page is being replaced; target_data cleared. */
+#define PAGE_RESET     0x0040
+
 #if defined(CONFIG_BSD) && defined(CONFIG_USER_ONLY)
 /* FIXME: Code that sets/uses this is broken and needs to go away.  */
-#define PAGE_RESERVED  0x0020
+#define PAGE_RESERVED  0x0100
 #endif
 /* Target-specific bits that will be used via page_get_flags().  */
 #define PAGE_TARGET_1  0x0080
@@ -279,6 +285,30 @@ int walk_memory_regions(void *, walk_memory_regions_fn);
 int page_get_flags(target_ulong address);
 void page_set_flags(target_ulong start, target_ulong end, int flags);
 int page_check_range(target_ulong start, target_ulong len, int flags);
+
+/**
+ * page_alloc_target_data(address, size)
+ * @address: guest virtual address
+ * @size: size of data to allocate
+ *
+ * Allocate @size bytes of out-of-band data to associate with the
+ * guest page at @address.  If the page is not mapped, NULL will
+ * be returned.  If there is existing data associated with @address,
+ * no new memory will be allocated.
+ *
+ * The memory will be freed when the guest page is deallocated,
+ * e.g. with the munmap system call.
+ */
+void *page_alloc_target_data(target_ulong address, size_t size);
+
+/**
+ * page_get_target_data(address)
+ * @address: guest virtual address
+ *
+ * Return any out-of-bound memory assocated with the guest page
+ * at @address, as per page_alloc_target_data.
+ */
+void *page_get_target_data(target_ulong address);
 #endif
 
 CPUArchState *cpu_copy(CPUArchState *env);