[PULL 24/40] linux-user/aarch64: Implement PROT_MTE

[Peter Maydell]

From: Richard Henderson <richard.henderson@linaro.org>

Remember the PROT_MTE bit as PAGE_MTE/PAGE_TARGET_2.
Otherwise this does not yet have effect.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210212184902.1251044-25-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 include/exec/cpu-all.h    |  1 +
 linux-user/syscall_defs.h |  1 +
 target/arm/cpu.h          |  1 +
 linux-user/mmap.c         | 22 ++++++++++++++--------
 4 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
index 937becd320a..76443eb11d5 100644
--- a/include/exec/cpu-all.h
+++ b/include/exec/cpu-all.h
@@ -276,6 +276,7 @@ extern intptr_t qemu_host_page_mask;
 #endif
 /* Target-specific bits that will be used via page_get_flags().  */
 #define PAGE_TARGET_1  0x0080
+#define PAGE_TARGET_2  0x0200
 
 #if defined(CONFIG_USER_ONLY)
 void page_dump(FILE *f);
diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h
index f98c1c1c8de..46a960fccb4 100644
--- a/linux-user/syscall_defs.h
+++ b/linux-user/syscall_defs.h
@@ -1311,6 +1311,7 @@ struct target_winsize {
 
 #ifdef TARGET_AARCH64
 #define TARGET_PROT_BTI         0x10
+#define TARGET_PROT_MTE         0x20
 #endif
 
 /* Common */
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 72a0819eb8c..efa1618c4d5 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -3608,6 +3608,7 @@ static inline MemTxAttrs *typecheck_memtxattrs(MemTxAttrs 
*x)
  * AArch64 usage of the PAGE_TARGET_* bits for linux-user.
  */
 #define PAGE_BTI  PAGE_TARGET_1
+#define PAGE_MTE  PAGE_TARGET_2
 
 #ifdef TARGET_TAGGED_ADDRESSES
 /**
diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 9fe0c634e24..7e3b2450368 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -84,18 +84,24 @@ static int validate_prot_to_pageflags(int *host_prot, int 
prot)
                | (prot & PROT_EXEC ? PROT_READ : 0);
 
 #ifdef TARGET_AARCH64
-    /*
-     * The PROT_BTI bit is only accepted if the cpu supports the feature.
-     * Since this is the unusual case, don't bother checking unless
-     * the bit has been requested.  If set and valid, record the bit
-     * within QEMU's page_flags.
-     */
-    if (prot & TARGET_PROT_BTI) {
+    {
         ARMCPU *cpu = ARM_CPU(thread_cpu);
-        if (cpu_isar_feature(aa64_bti, cpu)) {
+
+        /*
+         * The PROT_BTI bit is only accepted if the cpu supports the feature.
+         * Since this is the unusual case, don't bother checking unless
+         * the bit has been requested.  If set and valid, record the bit
+         * within QEMU's page_flags.
+         */
+        if ((prot & TARGET_PROT_BTI) && cpu_isar_feature(aa64_bti, cpu)) {
             valid |= TARGET_PROT_BTI;
             page_flags |= PAGE_BTI;
         }
+        /* Similarly for the PROT_MTE bit. */
+        if ((prot & TARGET_PROT_MTE) && cpu_isar_feature(aa64_mte, cpu)) {
+            valid |= TARGET_PROT_MTE;
+            page_flags |= PAGE_MTE;
+        }
     }
 #endif
 
-- 
2.20.1