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From: Richard Henderson <richard.henderson@linaro.org>
To: qemu-devel@nongnu.org
Cc: qemu-arm@nongnu.org, Stephen Long <steplong@quicinc.com>
Subject: [PATCH v3 01/11] accel/tcg: Preserve PAGE_ANON when changing page permissions
Date: Fri,  2 Apr 2021 14:42:07 -0700	[thread overview]
Message-ID: <20210402214217.422585-2-richard.henderson@linaro.org> (raw)
In-Reply-To: <20210402214217.422585-1-richard.henderson@linaro.org>

Using mprotect() to change PROT_* does not change the MAP_ANON
previously set with mmap().  Our linux-user version of MTE only
works with MAP_ANON pages, so losing PAGE_ANON caused MTE to
stop working.

Reported-by: Stephen Long <steplong@quicinc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tests/tcg/aarch64/mte.h           |  3 ++-
 accel/tcg/translate-all.c         |  9 +++++--
 tests/tcg/aarch64/mte-6.c         | 43 +++++++++++++++++++++++++++++++
 tests/tcg/aarch64/Makefile.target |  2 +-
 4 files changed, 53 insertions(+), 4 deletions(-)
 create mode 100644 tests/tcg/aarch64/mte-6.c

diff --git a/tests/tcg/aarch64/mte.h b/tests/tcg/aarch64/mte.h
index 141cef522c..0805676b11 100644
--- a/tests/tcg/aarch64/mte.h
+++ b/tests/tcg/aarch64/mte.h
@@ -48,7 +48,8 @@ static void enable_mte(int tcf)
     }
 }
 
-static void *alloc_mte_mem(size_t size)
+static void * alloc_mte_mem(size_t size) __attribute__((unused));
+static void * alloc_mte_mem(size_t size)
 {
     void *p = mmap(NULL, size, PROT_READ | PROT_WRITE | PROT_MTE,
                    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index f32df8b240..ba6ab09790 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -2714,6 +2714,8 @@ void page_set_flags(target_ulong start, target_ulong end, int flags)
        a missing call to h2g_valid.  */
     assert(end - 1 <= GUEST_ADDR_MAX);
     assert(start < end);
+    /* Only set PAGE_ANON with new mappings. */
+    assert(!(flags & PAGE_ANON) || (flags & PAGE_RESET));
     assert_memory_lock();
 
     start = start & TARGET_PAGE_MASK;
@@ -2737,11 +2739,14 @@ void page_set_flags(target_ulong start, target_ulong end, int flags)
             p->first_tb) {
             tb_invalidate_phys_page(addr, 0);
         }
-        if (reset_target_data && p->target_data) {
+        if (reset_target_data) {
             g_free(p->target_data);
             p->target_data = NULL;
+            p->flags = flags;
+        } else {
+            /* Using mprotect on a page does not change MAP_ANON. */
+            p->flags = (p->flags & PAGE_ANON) | flags;
         }
-        p->flags = flags;
     }
 }
 
diff --git a/tests/tcg/aarch64/mte-6.c b/tests/tcg/aarch64/mte-6.c
new file mode 100644
index 0000000000..60d51d18be
--- /dev/null
+++ b/tests/tcg/aarch64/mte-6.c
@@ -0,0 +1,43 @@
+#include "mte.h"
+
+void pass(int sig, siginfo_t *info, void *uc)
+{
+    assert(info->si_code == SEGV_MTESERR);
+    exit(0);
+}
+
+int main(void)
+{
+    enable_mte(PR_MTE_TCF_SYNC);
+
+    void *brk = sbrk(16);
+    if (brk == (void *)-1) {
+        perror("sbrk");
+        return 2;
+    }
+
+    if (mprotect(brk, 16, PROT_READ | PROT_WRITE | PROT_MTE)) {
+        perror("mprotect");
+        return 2;
+    }
+
+    int *p1, *p2;
+    long excl = 1;
+
+    asm("irg %0,%1,%2" : "=r"(p1) : "r"(brk), "r"(excl));
+    asm("gmi %0,%1,%0" : "+r"(excl) : "r"(p1));
+    asm("irg %0,%1,%2" : "=r"(p2) : "r"(brk), "r"(excl));
+    asm("stg %0,[%0]" : : "r"(p1));
+
+    *p1 = 0;
+
+    struct sigaction sa;
+    memset(&sa, 0, sizeof(sa));
+    sa.sa_sigaction = pass;
+    sa.sa_flags = SA_SIGINFO;
+    sigaction(SIGSEGV, &sa, NULL);
+
+    *p2 = 0;
+
+    abort();
+}
diff --git a/tests/tcg/aarch64/Makefile.target b/tests/tcg/aarch64/Makefile.target
index 56e48f4b34..05b2622bfc 100644
--- a/tests/tcg/aarch64/Makefile.target
+++ b/tests/tcg/aarch64/Makefile.target
@@ -37,7 +37,7 @@ AARCH64_TESTS += bti-2
 
 # MTE Tests
 ifneq ($(DOCKER_IMAGE)$(CROSS_CC_HAS_ARMV8_MTE),)
-AARCH64_TESTS += mte-1 mte-2 mte-3 mte-4
+AARCH64_TESTS += mte-1 mte-2 mte-3 mte-4 mte-6
 mte-%: CFLAGS += -march=armv8.5-a+memtag
 endif
 
-- 
2.25.1



  reply	other threads:[~2021-04-02 21:43 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-02 21:42 [PATCH v3 00/11] target/arm mte fixes Richard Henderson
2021-04-02 21:42 ` Richard Henderson [this message]
2021-04-02 21:42 ` [PATCH v3 02/11] target/arm: Check PAGE_WRITE_ORG for MTE writeability Richard Henderson
2021-04-02 21:42 ` [PATCH v3 03/11] target/arm: Fix unaligned mte checks for mte_checkN Richard Henderson
2021-04-02 21:42 ` [PATCH v3 04/11] target/arm: Split out mte_probe_int Richard Henderson
2021-04-02 21:42 ` [PATCH v3 05/11] target/arm: Fix unaligned checks for mte_check1, mte_probe1 Richard Henderson
2021-04-02 21:42 ` [PATCH v3 06/11] test/tcg/aarch64: Add mte-5 Richard Henderson
2021-04-02 21:42 ` [PATCH v3 07/11] target/arm: Replace MTEDESC ESIZE+TSIZE with SIZEM1 Richard Henderson
2021-04-02 21:42 ` [PATCH v3 08/11] target/arm: Merge mte_check1, mte_checkN Richard Henderson
2021-04-02 21:42 ` [PATCH v3 09/11] target/arm: Rename mte_probe1 to mte_probe Richard Henderson
2021-04-02 21:42 ` [PATCH v3 10/11] target/arm: Simplify sve mte checking Richard Henderson
2021-04-02 21:42 ` [PATCH v3 11/11] target/arm: Remove log2_esize parameter to gen_mte_checkN Richard Henderson
2021-04-02 21:54 ` [PATCH v3 00/11] target/arm mte fixes no-reply
2021-04-03 19:46 ` Richard Henderson

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