diff mbox series

[v4,17/43] tcg: Add --accel tcg,split-wx property

Message ID 20201214140314.18544-18-richard.henderson@linaro.org
State Superseded
Headers show
Series Mirror map JIT memory for TCG | expand

Commit Message

Richard Henderson Dec. 14, 2020, 2:02 p.m. UTC 
Plumb the value through to alloc_code_gen_buffer.  This is not
supported by any os or tcg backend, so for now enabling it will
result in an error.

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

---
 include/sysemu/tcg.h      |  3 ++-
 tcg/aarch64/tcg-target.h  |  1 +
 tcg/arm/tcg-target.h      |  1 +
 tcg/i386/tcg-target.h     |  1 +
 tcg/mips/tcg-target.h     |  1 +
 tcg/ppc/tcg-target.h      |  1 +
 tcg/riscv/tcg-target.h    |  1 +
 tcg/s390/tcg-target.h     |  1 +
 tcg/sparc/tcg-target.h    |  1 +
 tcg/tci/tcg-target.h      |  1 +
 accel/tcg/tcg-all.c       | 26 +++++++++++++++++++++++++-
 accel/tcg/translate-all.c | 35 +++++++++++++++++++++++++++--------
 bsd-user/main.c           |  2 +-
 linux-user/main.c         |  2 +-
 14 files changed, 65 insertions(+), 12 deletions(-)

-- 
2.25.1

Comments

Joelle van Dyne Dec. 15, 2020, 2:05 a.m. UTC | #1 
Should qemu-options.hx be updated?

-j

On Mon, Dec 14, 2020 at 6:02 AM Richard Henderson
<richard.henderson@linaro.org> wrote:
>

> Plumb the value through to alloc_code_gen_buffer.  This is not

> supported by any os or tcg backend, so for now enabling it will

> result in an error.

>

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

> ---

>  include/sysemu/tcg.h      |  3 ++-

>  tcg/aarch64/tcg-target.h  |  1 +

>  tcg/arm/tcg-target.h      |  1 +

>  tcg/i386/tcg-target.h     |  1 +

>  tcg/mips/tcg-target.h     |  1 +

>  tcg/ppc/tcg-target.h      |  1 +

>  tcg/riscv/tcg-target.h    |  1 +

>  tcg/s390/tcg-target.h     |  1 +

>  tcg/sparc/tcg-target.h    |  1 +

>  tcg/tci/tcg-target.h      |  1 +

>  accel/tcg/tcg-all.c       | 26 +++++++++++++++++++++++++-

>  accel/tcg/translate-all.c | 35 +++++++++++++++++++++++++++--------

>  bsd-user/main.c           |  2 +-

>  linux-user/main.c         |  2 +-

>  14 files changed, 65 insertions(+), 12 deletions(-)

>

> diff --git a/include/sysemu/tcg.h b/include/sysemu/tcg.h

> index d9d3ca8559..00349fb18a 100644

> --- a/include/sysemu/tcg.h

> +++ b/include/sysemu/tcg.h

> @@ -8,7 +8,8 @@

>  #ifndef SYSEMU_TCG_H

>  #define SYSEMU_TCG_H

>

> -void tcg_exec_init(unsigned long tb_size);

> +void tcg_exec_init(unsigned long tb_size, int splitwx);

> +

>  #ifdef CONFIG_TCG

>  extern bool tcg_allowed;

>  #define tcg_enabled() (tcg_allowed)

> diff --git a/tcg/aarch64/tcg-target.h b/tcg/aarch64/tcg-target.h

> index 6ba248f447..92aefc32d3 100644

> --- a/tcg/aarch64/tcg-target.h

> +++ b/tcg/aarch64/tcg-target.h

> @@ -154,5 +154,6 @@ void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);

>  #define TCG_TARGET_NEED_LDST_LABELS

>  #endif

>  #define TCG_TARGET_NEED_POOL_LABELS

> +#define TCG_TARGET_SUPPORT_MIRROR       0

>

>  #endif /* AARCH64_TCG_TARGET_H */

> diff --git a/tcg/arm/tcg-target.h b/tcg/arm/tcg-target.h

> index 6ca4537ca6..7e04755428 100644

> --- a/tcg/arm/tcg-target.h

> +++ b/tcg/arm/tcg-target.h

> @@ -141,5 +141,6 @@ void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);

>  #define TCG_TARGET_NEED_LDST_LABELS

>  #endif

>  #define TCG_TARGET_NEED_POOL_LABELS

> +#define TCG_TARGET_SUPPORT_MIRROR       0

>

>  #endif

> diff --git a/tcg/i386/tcg-target.h b/tcg/i386/tcg-target.h

> index 0dcaed7fe6..04eefbfb90 100644

> --- a/tcg/i386/tcg-target.h

> +++ b/tcg/i386/tcg-target.h

> @@ -231,5 +231,6 @@ static inline void tb_target_set_jmp_target(uintptr_t tc_ptr, uintptr_t jmp_rx,

>  #define TCG_TARGET_NEED_LDST_LABELS

>  #endif

>  #define TCG_TARGET_NEED_POOL_LABELS

> +#define TCG_TARGET_SUPPORT_MIRROR       0

>

>  #endif

> diff --git a/tcg/mips/tcg-target.h b/tcg/mips/tcg-target.h

> index d23baf7cda..d6dff897bf 100644

> --- a/tcg/mips/tcg-target.h

> +++ b/tcg/mips/tcg-target.h

> @@ -200,6 +200,7 @@ extern bool use_mips32r2_instructions;

>

>  #define TCG_TARGET_DEFAULT_MO (0)

>  #define TCG_TARGET_HAS_MEMORY_BSWAP     1

> +#define TCG_TARGET_SUPPORT_MIRROR       0

>

>  void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);

>

> diff --git a/tcg/ppc/tcg-target.h b/tcg/ppc/tcg-target.h

> index c41d10142b..8fc2672bf0 100644

> --- a/tcg/ppc/tcg-target.h

> +++ b/tcg/ppc/tcg-target.h

> @@ -184,5 +184,6 @@ void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);

>  #define TCG_TARGET_NEED_LDST_LABELS

>  #endif

>  #define TCG_TARGET_NEED_POOL_LABELS

> +#define TCG_TARGET_SUPPORT_MIRROR       0

>

>  #endif

> diff --git a/tcg/riscv/tcg-target.h b/tcg/riscv/tcg-target.h

> index 3d0745c70c..785fe37f9b 100644

> --- a/tcg/riscv/tcg-target.h

> +++ b/tcg/riscv/tcg-target.h

> @@ -170,5 +170,6 @@ void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);

>  #define TCG_TARGET_NEED_POOL_LABELS

>

>  #define TCG_TARGET_HAS_MEMORY_BSWAP 0

> +#define TCG_TARGET_SUPPORT_MIRROR   0

>

>  #endif

> diff --git a/tcg/s390/tcg-target.h b/tcg/s390/tcg-target.h

> index 3750952598..fed3329e51 100644

> --- a/tcg/s390/tcg-target.h

> +++ b/tcg/s390/tcg-target.h

> @@ -158,5 +158,6 @@ static inline void tb_target_set_jmp_target(uintptr_t tc_ptr, uintptr_t jmp_rx,

>  #define TCG_TARGET_NEED_LDST_LABELS

>  #endif

>  #define TCG_TARGET_NEED_POOL_LABELS

> +#define TCG_TARGET_SUPPORT_MIRROR       0

>

>  #endif

> diff --git a/tcg/sparc/tcg-target.h b/tcg/sparc/tcg-target.h

> index 9c15c91d39..21e7e2f56f 100644

> --- a/tcg/sparc/tcg-target.h

> +++ b/tcg/sparc/tcg-target.h

> @@ -171,5 +171,6 @@ extern bool use_vis3_instructions;

>  void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);

>

>  #define TCG_TARGET_NEED_POOL_LABELS

> +#define TCG_TARGET_SUPPORT_MIRROR       0

>

>  #endif

> diff --git a/tcg/tci/tcg-target.h b/tcg/tci/tcg-target.h

> index fcec2e70db..768153fd02 100644

> --- a/tcg/tci/tcg-target.h

> +++ b/tcg/tci/tcg-target.h

> @@ -197,6 +197,7 @@ void tci_disas(uint8_t opc);

>  #define TCG_TARGET_DEFAULT_MO  (0)

>

>  #define TCG_TARGET_HAS_MEMORY_BSWAP     1

> +#define TCG_TARGET_SUPPORT_MIRROR       0

>

>  static inline void tb_target_set_jmp_target(uintptr_t tc_ptr, uintptr_t jmp_rx,

>                                              uintptr_t jmp_rw, uintptr_t addr)

> diff --git a/accel/tcg/tcg-all.c b/accel/tcg/tcg-all.c

> index 1ac0b76515..2eea8c32ee 100644

> --- a/accel/tcg/tcg-all.c

> +++ b/accel/tcg/tcg-all.c

> @@ -38,6 +38,7 @@ struct TCGState {

>      AccelState parent_obj;

>

>      bool mttcg_enabled;

> +    int splitwx_enabled;

>      unsigned long tb_size;

>  };

>  typedef struct TCGState TCGState;

> @@ -94,6 +95,13 @@ static void tcg_accel_instance_init(Object *obj)

>      TCGState *s = TCG_STATE(obj);

>

>      s->mttcg_enabled = default_mttcg_enabled();

> +

> +    /* If debugging enabled, default "auto on", otherwise off. */

> +#ifdef CONFIG_DEBUG_TCG

> +    s->splitwx_enabled = -1;

> +#else

> +    s->splitwx_enabled = 0;

> +#endif

>  }

>

>  bool mttcg_enabled;

> @@ -102,7 +110,7 @@ static int tcg_init(MachineState *ms)

>  {

>      TCGState *s = TCG_STATE(current_accel());

>

> -    tcg_exec_init(s->tb_size * 1024 * 1024);

> +    tcg_exec_init(s->tb_size * 1024 * 1024, s->splitwx_enabled);

>      mttcg_enabled = s->mttcg_enabled;

>

>      /*

> @@ -179,6 +187,18 @@ static void tcg_set_tb_size(Object *obj, Visitor *v,

>      s->tb_size = value;

>  }

>

> +static bool tcg_get_splitwx(Object *obj, Error **errp)

> +{

> +    TCGState *s = TCG_STATE(obj);

> +    return s->splitwx_enabled;

> +}

> +

> +static void tcg_set_splitwx(Object *obj, bool value, Error **errp)

> +{

> +    TCGState *s = TCG_STATE(obj);

> +    s->splitwx_enabled = value;

> +}

> +

>  static void tcg_accel_class_init(ObjectClass *oc, void *data)

>  {

>      AccelClass *ac = ACCEL_CLASS(oc);

> @@ -196,6 +216,10 @@ static void tcg_accel_class_init(ObjectClass *oc, void *data)

>      object_class_property_set_description(oc, "tb-size",

>          "TCG translation block cache size");

>

> +    object_class_property_add_bool(oc, "split-wx",

> +        tcg_get_splitwx, tcg_set_splitwx);

> +    object_class_property_set_description(oc, "split-wx",

> +        "Map jit pages into separate RW and RX regions");

>  }

>

>  static const TypeInfo tcg_accel_type = {

> diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c

> index 2824b3e387..a29cb4a42e 100644

> --- a/accel/tcg/translate-all.c

> +++ b/accel/tcg/translate-all.c

> @@ -1015,13 +1015,19 @@ static inline void *split_cross_256mb(void *buf1, size_t size1)

>  static uint8_t static_code_gen_buffer[DEFAULT_CODE_GEN_BUFFER_SIZE]

>      __attribute__((aligned(CODE_GEN_ALIGN)));

>

> -static bool alloc_code_gen_buffer(size_t tb_size, Error **errp)

> +static bool alloc_code_gen_buffer(size_t tb_size, int splitwx, Error **errp)

>  {

> -    void *buf = static_code_gen_buffer;

> -    void *end = static_code_gen_buffer + sizeof(static_code_gen_buffer);

> +    void *buf, *end;

>      size_t size;

>

> +    if (splitwx > 0) {

> +        error_setg(errp, "jit split-wx not supported");

> +        return false;

> +    }

> +

>      /* page-align the beginning and end of the buffer */

> +    buf = static_code_gen_buffer;

> +    end = static_code_gen_buffer + sizeof(static_code_gen_buffer);

>      buf = QEMU_ALIGN_PTR_UP(buf, qemu_real_host_page_size);

>      end = QEMU_ALIGN_PTR_DOWN(end, qemu_real_host_page_size);

>

> @@ -1050,9 +1056,16 @@ static bool alloc_code_gen_buffer(size_t tb_size, Error **errp)

>      return true;

>  }

>  #elif defined(_WIN32)

> -static bool alloc_code_gen_buffer(size_t size, Error **errp)

> +static bool alloc_code_gen_buffer(size_t size, int splitwx, Error **errp)

>  {

> -    void *buf = VirtualAlloc(NULL, size, MEM_RESERVE | MEM_COMMIT,

> +    void *buf;

> +

> +    if (splitwx > 0) {

> +        error_setg(errp, "jit split-wx not supported");

> +        return false;

> +    }

> +

> +    buf = VirtualAlloc(NULL, size, MEM_RESERVE | MEM_COMMIT,

>                               PAGE_EXECUTE_READWRITE);

>      if (buf == NULL) {

>          error_setg_win32(errp, GetLastError(),

> @@ -1065,12 +1078,17 @@ static bool alloc_code_gen_buffer(size_t size, Error **errp)

>      return true;

>  }

>  #else

> -static bool alloc_code_gen_buffer(size_t size, Error **errp)

> +static bool alloc_code_gen_buffer(size_t size, int splitwx, Error **errp)

>  {

>      int prot = PROT_WRITE | PROT_READ | PROT_EXEC;

>      int flags = MAP_PRIVATE | MAP_ANONYMOUS;

>      void *buf;

>

> +    if (splitwx > 0) {

> +        error_setg(errp, "jit split-wx not supported");

> +        return false;

> +    }

> +

>      buf = mmap(NULL, size, prot, flags, -1, 0);

>      if (buf == MAP_FAILED) {

>          error_setg_errno(errp, errno,

> @@ -1145,7 +1163,7 @@ static void tb_htable_init(void)

>  /* Must be called before using the QEMU cpus. 'tb_size' is the size

>     (in bytes) allocated to the translation buffer. Zero means default

>     size. */

> -void tcg_exec_init(unsigned long tb_size)

> +void tcg_exec_init(unsigned long tb_size, int splitwx)

>  {

>      bool ok;

>

> @@ -1154,7 +1172,8 @@ void tcg_exec_init(unsigned long tb_size)

>      page_init();

>      tb_htable_init();

>

> -    ok = alloc_code_gen_buffer(size_code_gen_buffer(tb_size), &error_fatal);

> +    ok = alloc_code_gen_buffer(size_code_gen_buffer(tb_size),

> +                               splitwx, &error_fatal);

>      assert(ok);

>

>  #if defined(CONFIG_SOFTMMU)

> diff --git a/bsd-user/main.c b/bsd-user/main.c

> index 0a918e8f74..086351fc6f 100644

> --- a/bsd-user/main.c

> +++ b/bsd-user/main.c

> @@ -908,7 +908,7 @@ int main(int argc, char **argv)

>      }

>

>      /* init tcg before creating CPUs and to get qemu_host_page_size */

> -    tcg_exec_init(0);

> +    tcg_exec_init(0, false);

>

>      cpu_type = parse_cpu_option(cpu_model);

>      cpu = cpu_create(cpu_type);

> diff --git a/linux-user/main.c b/linux-user/main.c

> index 24d1eb73ad..5ff8100770 100644

> --- a/linux-user/main.c

> +++ b/linux-user/main.c

> @@ -703,7 +703,7 @@ int main(int argc, char **argv, char **envp)

>      cpu_type = parse_cpu_option(cpu_model);

>

>      /* init tcg before creating CPUs and to get qemu_host_page_size */

> -    tcg_exec_init(0);

> +    tcg_exec_init(0, false);

>

>      cpu = cpu_create(cpu_type);

>      env = cpu->env_ptr;

> --

> 2.25.1

>
Richard Henderson Dec. 15, 2020, 10:50 p.m. UTC | #2 
On 12/14/20 8:05 PM, Joelle van Dyne wrote:
> Should qemu-options.hx be updated?


Yep, good catch.


r~
diff mbox series

Patch

diff --git a/include/sysemu/tcg.h b/include/sysemu/tcg.h
index d9d3ca8559..00349fb18a 100644
--- a/include/sysemu/tcg.h
+++ b/include/sysemu/tcg.h
@@ -8,7 +8,8 @@ 
 #ifndef SYSEMU_TCG_H
 #define SYSEMU_TCG_H
 
-void tcg_exec_init(unsigned long tb_size);
+void tcg_exec_init(unsigned long tb_size, int splitwx);
+
 #ifdef CONFIG_TCG
 extern bool tcg_allowed;
 #define tcg_enabled() (tcg_allowed)
diff --git a/tcg/aarch64/tcg-target.h b/tcg/aarch64/tcg-target.h
index 6ba248f447..92aefc32d3 100644
--- a/tcg/aarch64/tcg-target.h
+++ b/tcg/aarch64/tcg-target.h
@@ -154,5 +154,6 @@  void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);
 #define TCG_TARGET_NEED_LDST_LABELS
 #endif
 #define TCG_TARGET_NEED_POOL_LABELS
+#define TCG_TARGET_SUPPORT_MIRROR       0
 
 #endif /* AARCH64_TCG_TARGET_H */
diff --git a/tcg/arm/tcg-target.h b/tcg/arm/tcg-target.h
index 6ca4537ca6..7e04755428 100644
--- a/tcg/arm/tcg-target.h
+++ b/tcg/arm/tcg-target.h
@@ -141,5 +141,6 @@  void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);
 #define TCG_TARGET_NEED_LDST_LABELS
 #endif
 #define TCG_TARGET_NEED_POOL_LABELS
+#define TCG_TARGET_SUPPORT_MIRROR       0
 
 #endif
diff --git a/tcg/i386/tcg-target.h b/tcg/i386/tcg-target.h
index 0dcaed7fe6..04eefbfb90 100644
--- a/tcg/i386/tcg-target.h
+++ b/tcg/i386/tcg-target.h
@@ -231,5 +231,6 @@  static inline void tb_target_set_jmp_target(uintptr_t tc_ptr, uintptr_t jmp_rx,
 #define TCG_TARGET_NEED_LDST_LABELS
 #endif
 #define TCG_TARGET_NEED_POOL_LABELS
+#define TCG_TARGET_SUPPORT_MIRROR       0
 
 #endif
diff --git a/tcg/mips/tcg-target.h b/tcg/mips/tcg-target.h
index d23baf7cda..d6dff897bf 100644
--- a/tcg/mips/tcg-target.h
+++ b/tcg/mips/tcg-target.h
@@ -200,6 +200,7 @@  extern bool use_mips32r2_instructions;
 
 #define TCG_TARGET_DEFAULT_MO (0)
 #define TCG_TARGET_HAS_MEMORY_BSWAP     1
+#define TCG_TARGET_SUPPORT_MIRROR       0
 
 void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);
 
diff --git a/tcg/ppc/tcg-target.h b/tcg/ppc/tcg-target.h
index c41d10142b..8fc2672bf0 100644
--- a/tcg/ppc/tcg-target.h
+++ b/tcg/ppc/tcg-target.h
@@ -184,5 +184,6 @@  void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);
 #define TCG_TARGET_NEED_LDST_LABELS
 #endif
 #define TCG_TARGET_NEED_POOL_LABELS
+#define TCG_TARGET_SUPPORT_MIRROR       0
 
 #endif
diff --git a/tcg/riscv/tcg-target.h b/tcg/riscv/tcg-target.h
index 3d0745c70c..785fe37f9b 100644
--- a/tcg/riscv/tcg-target.h
+++ b/tcg/riscv/tcg-target.h
@@ -170,5 +170,6 @@  void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);
 #define TCG_TARGET_NEED_POOL_LABELS
 
 #define TCG_TARGET_HAS_MEMORY_BSWAP 0
+#define TCG_TARGET_SUPPORT_MIRROR   0
 
 #endif
diff --git a/tcg/s390/tcg-target.h b/tcg/s390/tcg-target.h
index 3750952598..fed3329e51 100644
--- a/tcg/s390/tcg-target.h
+++ b/tcg/s390/tcg-target.h
@@ -158,5 +158,6 @@  static inline void tb_target_set_jmp_target(uintptr_t tc_ptr, uintptr_t jmp_rx,
 #define TCG_TARGET_NEED_LDST_LABELS
 #endif
 #define TCG_TARGET_NEED_POOL_LABELS
+#define TCG_TARGET_SUPPORT_MIRROR       0
 
 #endif
diff --git a/tcg/sparc/tcg-target.h b/tcg/sparc/tcg-target.h
index 9c15c91d39..21e7e2f56f 100644
--- a/tcg/sparc/tcg-target.h
+++ b/tcg/sparc/tcg-target.h
@@ -171,5 +171,6 @@  extern bool use_vis3_instructions;
 void tb_target_set_jmp_target(uintptr_t, uintptr_t, uintptr_t, uintptr_t);
 
 #define TCG_TARGET_NEED_POOL_LABELS
+#define TCG_TARGET_SUPPORT_MIRROR       0
 
 #endif
diff --git a/tcg/tci/tcg-target.h b/tcg/tci/tcg-target.h
index fcec2e70db..768153fd02 100644
--- a/tcg/tci/tcg-target.h
+++ b/tcg/tci/tcg-target.h
@@ -197,6 +197,7 @@  void tci_disas(uint8_t opc);
 #define TCG_TARGET_DEFAULT_MO  (0)
 
 #define TCG_TARGET_HAS_MEMORY_BSWAP     1
+#define TCG_TARGET_SUPPORT_MIRROR       0
 
 static inline void tb_target_set_jmp_target(uintptr_t tc_ptr, uintptr_t jmp_rx,
                                             uintptr_t jmp_rw, uintptr_t addr)
diff --git a/accel/tcg/tcg-all.c b/accel/tcg/tcg-all.c
index 1ac0b76515..2eea8c32ee 100644
--- a/accel/tcg/tcg-all.c
+++ b/accel/tcg/tcg-all.c
@@ -38,6 +38,7 @@  struct TCGState {
     AccelState parent_obj;
 
     bool mttcg_enabled;
+    int splitwx_enabled;
     unsigned long tb_size;
 };
 typedef struct TCGState TCGState;
@@ -94,6 +95,13 @@  static void tcg_accel_instance_init(Object *obj)
     TCGState *s = TCG_STATE(obj);
 
     s->mttcg_enabled = default_mttcg_enabled();
+
+    /* If debugging enabled, default "auto on", otherwise off. */
+#ifdef CONFIG_DEBUG_TCG
+    s->splitwx_enabled = -1;
+#else
+    s->splitwx_enabled = 0;
+#endif
 }
 
 bool mttcg_enabled;
@@ -102,7 +110,7 @@  static int tcg_init(MachineState *ms)
 {
     TCGState *s = TCG_STATE(current_accel());
 
-    tcg_exec_init(s->tb_size * 1024 * 1024);
+    tcg_exec_init(s->tb_size * 1024 * 1024, s->splitwx_enabled);
     mttcg_enabled = s->mttcg_enabled;
 
     /*
@@ -179,6 +187,18 @@  static void tcg_set_tb_size(Object *obj, Visitor *v,
     s->tb_size = value;
 }
 
+static bool tcg_get_splitwx(Object *obj, Error **errp)
+{
+    TCGState *s = TCG_STATE(obj);
+    return s->splitwx_enabled;
+}
+
+static void tcg_set_splitwx(Object *obj, bool value, Error **errp)
+{
+    TCGState *s = TCG_STATE(obj);
+    s->splitwx_enabled = value;
+}
+
 static void tcg_accel_class_init(ObjectClass *oc, void *data)
 {
     AccelClass *ac = ACCEL_CLASS(oc);
@@ -196,6 +216,10 @@  static void tcg_accel_class_init(ObjectClass *oc, void *data)
     object_class_property_set_description(oc, "tb-size",
         "TCG translation block cache size");
 
+    object_class_property_add_bool(oc, "split-wx",
+        tcg_get_splitwx, tcg_set_splitwx);
+    object_class_property_set_description(oc, "split-wx",
+        "Map jit pages into separate RW and RX regions");
 }
 
 static const TypeInfo tcg_accel_type = {
diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index 2824b3e387..a29cb4a42e 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -1015,13 +1015,19 @@  static inline void *split_cross_256mb(void *buf1, size_t size1)
 static uint8_t static_code_gen_buffer[DEFAULT_CODE_GEN_BUFFER_SIZE]
     __attribute__((aligned(CODE_GEN_ALIGN)));
 
-static bool alloc_code_gen_buffer(size_t tb_size, Error **errp)
+static bool alloc_code_gen_buffer(size_t tb_size, int splitwx, Error **errp)
 {
-    void *buf = static_code_gen_buffer;
-    void *end = static_code_gen_buffer + sizeof(static_code_gen_buffer);
+    void *buf, *end;
     size_t size;
 
+    if (splitwx > 0) {
+        error_setg(errp, "jit split-wx not supported");
+        return false;
+    }
+
     /* page-align the beginning and end of the buffer */
+    buf = static_code_gen_buffer;
+    end = static_code_gen_buffer + sizeof(static_code_gen_buffer);
     buf = QEMU_ALIGN_PTR_UP(buf, qemu_real_host_page_size);
     end = QEMU_ALIGN_PTR_DOWN(end, qemu_real_host_page_size);
 
@@ -1050,9 +1056,16 @@  static bool alloc_code_gen_buffer(size_t tb_size, Error **errp)
     return true;
 }
 #elif defined(_WIN32)
-static bool alloc_code_gen_buffer(size_t size, Error **errp)
+static bool alloc_code_gen_buffer(size_t size, int splitwx, Error **errp)
 {
-    void *buf = VirtualAlloc(NULL, size, MEM_RESERVE | MEM_COMMIT,
+    void *buf;
+
+    if (splitwx > 0) {
+        error_setg(errp, "jit split-wx not supported");
+        return false;
+    }
+
+    buf = VirtualAlloc(NULL, size, MEM_RESERVE | MEM_COMMIT,
                              PAGE_EXECUTE_READWRITE);
     if (buf == NULL) {
         error_setg_win32(errp, GetLastError(),
@@ -1065,12 +1078,17 @@  static bool alloc_code_gen_buffer(size_t size, Error **errp)
     return true;
 }
 #else
-static bool alloc_code_gen_buffer(size_t size, Error **errp)
+static bool alloc_code_gen_buffer(size_t size, int splitwx, Error **errp)
 {
     int prot = PROT_WRITE | PROT_READ | PROT_EXEC;
     int flags = MAP_PRIVATE | MAP_ANONYMOUS;
     void *buf;
 
+    if (splitwx > 0) {
+        error_setg(errp, "jit split-wx not supported");
+        return false;
+    }
+
     buf = mmap(NULL, size, prot, flags, -1, 0);
     if (buf == MAP_FAILED) {
         error_setg_errno(errp, errno,
@@ -1145,7 +1163,7 @@  static void tb_htable_init(void)
 /* Must be called before using the QEMU cpus. 'tb_size' is the size
    (in bytes) allocated to the translation buffer. Zero means default
    size. */
-void tcg_exec_init(unsigned long tb_size)
+void tcg_exec_init(unsigned long tb_size, int splitwx)
 {
     bool ok;
 
@@ -1154,7 +1172,8 @@  void tcg_exec_init(unsigned long tb_size)
     page_init();
     tb_htable_init();
 
-    ok = alloc_code_gen_buffer(size_code_gen_buffer(tb_size), &error_fatal);
+    ok = alloc_code_gen_buffer(size_code_gen_buffer(tb_size),
+                               splitwx, &error_fatal);
     assert(ok);
 
 #if defined(CONFIG_SOFTMMU)
diff --git a/bsd-user/main.c b/bsd-user/main.c
index 0a918e8f74..086351fc6f 100644
--- a/bsd-user/main.c
+++ b/bsd-user/main.c
@@ -908,7 +908,7 @@  int main(int argc, char **argv)
     }
 
     /* init tcg before creating CPUs and to get qemu_host_page_size */
-    tcg_exec_init(0);
+    tcg_exec_init(0, false);
 
     cpu_type = parse_cpu_option(cpu_model);
     cpu = cpu_create(cpu_type);
diff --git a/linux-user/main.c b/linux-user/main.c
index 24d1eb73ad..5ff8100770 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -703,7 +703,7 @@  int main(int argc, char **argv, char **envp)
     cpu_type = parse_cpu_option(cpu_model);
 
     /* init tcg before creating CPUs and to get qemu_host_page_size */
-    tcg_exec_init(0);
+    tcg_exec_init(0, false);
 
     cpu = cpu_create(cpu_type);
     env = cpu->env_ptr;