[v9,2/5] linux-user: Set PAGE_TARGET_1 for TARGET_PROT_BTI

Message ID 20200520172800.8499-3-richard.henderson@linaro.org
State New
Headers show
Series
  • linux-user: User support for AArch64 BTI
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Commit Message

Richard Henderson May 20, 2020, 5:27 p.m.
Transform the prot bit to a qemu internal page bit, and save
it in the page tables.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 include/exec/cpu-all.h     |  2 ++
 linux-user/syscall_defs.h  |  4 ++++
 linux-user/mmap.c          | 16 ++++++++++++++++
 target/arm/translate-a64.c |  6 +++---
 4 files changed, 25 insertions(+), 3 deletions(-)

-- 
2.20.1

Comments

Peter Maydell July 6, 2020, 11:09 a.m. | #1
On Wed, 20 May 2020 at 18:28, Richard Henderson
<richard.henderson@linaro.org> wrote:
>

> Transform the prot bit to a qemu internal page bit, and save

> it in the page tables.

>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

> ---

>  include/exec/cpu-all.h     |  2 ++

>  linux-user/syscall_defs.h  |  4 ++++

>  linux-user/mmap.c          | 16 ++++++++++++++++

>  target/arm/translate-a64.c |  6 +++---

>  4 files changed, 25 insertions(+), 3 deletions(-)

>

> diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h

> index d14374bdd4..2bd023d692 100644

> --- a/include/exec/cpu-all.h

> +++ b/include/exec/cpu-all.h

> @@ -276,6 +276,8 @@ extern intptr_t qemu_host_page_mask;

>  /* FIXME: Code that sets/uses this is broken and needs to go away.  */

>  #define PAGE_RESERVED  0x0020

>  #endif

> +/* Target-specific bits that will be used via page_get_flags().  */

> +#define PAGE_TARGET_1  0x0080


I think it would also be nice to have

/* Target-specific names for the target-specific bits */
#ifdef TARGET_AARCH64
#define PAGE_BTI PAGE_TARGET_1
#endif

which can then (a) act as documentation of which PAGE_TARGET_n
each target is actually using and (b) mean that code that's
using the target-specific bits can use more friendly names.

Otherwise
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>


thanks
-- PMM

Patch

diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
index d14374bdd4..2bd023d692 100644
--- a/include/exec/cpu-all.h
+++ b/include/exec/cpu-all.h
@@ -276,6 +276,8 @@  extern intptr_t qemu_host_page_mask;
 /* FIXME: Code that sets/uses this is broken and needs to go away.  */
 #define PAGE_RESERVED  0x0020
 #endif
+/* Target-specific bits that will be used via page_get_flags().  */
+#define PAGE_TARGET_1  0x0080
 
 #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 152ec637cb..36bdafb3f1 100644
--- a/linux-user/syscall_defs.h
+++ b/linux-user/syscall_defs.h
@@ -1194,6 +1194,10 @@  struct target_winsize {
 #define TARGET_PROT_SEM         0x08
 #endif
 
+#ifdef TARGET_AARCH64
+#define TARGET_PROT_BTI         0x10
+#endif
+
 /* Common */
 #define TARGET_MAP_SHARED	0x01		/* Share changes */
 #define TARGET_MAP_PRIVATE	0x02		/* Changes are private */
diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 84662c3311..40f03e3174 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -83,6 +83,22 @@  static int validate_prot_to_pageflags(int *host_prot, int prot)
     *host_prot = (prot & (PROT_READ | PROT_WRITE))
                | (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 as PAGE_TARGET_1.
+     */
+    if (prot & TARGET_PROT_BTI) {
+        ARMCPU *cpu = ARM_CPU(thread_cpu);
+        if (cpu_isar_feature(aa64_bti, cpu)) {
+            valid |= TARGET_PROT_BTI;
+            page_flags |= PAGE_TARGET_1;
+        }
+    }
+#endif
+
     return prot & ~valid ? 0 : page_flags;
 }
 
diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index 991e451644..59ae236c84 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -13989,10 +13989,10 @@  static void disas_data_proc_simd_fp(DisasContext *s, uint32_t insn)
  */
 static bool is_guarded_page(CPUARMState *env, DisasContext *s)
 {
-#ifdef CONFIG_USER_ONLY
-    return false;  /* FIXME */
-#else
     uint64_t addr = s->base.pc_first;
+#ifdef CONFIG_USER_ONLY
+    return page_get_flags(addr) & PAGE_TARGET_1;
+#else
     int mmu_idx = arm_to_core_mmu_idx(s->mmu_idx);
     unsigned int index = tlb_index(env, mmu_idx, addr);
     CPUTLBEntry *entry = tlb_entry(env, mmu_idx, addr);