tcg: Add --accel tcg,split-wx property
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.
Reviewed-by: Joelle van Dyne <j@getutm.app>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/accel/tcg/tcg-all.c b/accel/tcg/tcg-all.c
index 1ac0b76..2eea8c3 100644
--- a/accel/tcg/tcg-all.c
+++ b/accel/tcg/tcg-all.c
@@ -38,6 +38,7 @@
AccelState parent_obj;
bool mttcg_enabled;
+ int splitwx_enabled;
unsigned long tb_size;
};
typedef struct TCGState TCGState;
@@ -94,6 +95,13 @@
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 @@
{
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 @@
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 @@
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 ae87b23..022f9c7 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -1015,13 +1015,19 @@
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 @@
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 @@
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 @@
/* 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 @@
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 9c700c6..65163e1 100644
--- a/bsd-user/main.c
+++ b/bsd-user/main.c
@@ -909,7 +909,7 @@
}
/* 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/include/sysemu/tcg.h b/include/sysemu/tcg.h
index d9d3ca8..00349fb 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/linux-user/main.c b/linux-user/main.c
index 750a011..bb4e55e 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -701,7 +701,7 @@
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;
diff --git a/qemu-options.hx b/qemu-options.hx
index 459c916..1698a0c 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -115,6 +115,7 @@
" igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n"
" kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n"
" kvm-shadow-mem=size of KVM shadow MMU in bytes\n"
+ " split-wx=on|off (enable TCG split w^x mapping)\n"
" tb-size=n (TCG translation block cache size)\n"
" thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL)
SRST
@@ -140,6 +141,12 @@
``kvm-shadow-mem=size``
Defines the size of the KVM shadow MMU.
+ ``split-wx=on|off``
+ Controls the use of split w^x mapping for the TCG code generation
+ buffer. Some operating systems require this to be enabled, and in
+ such a case this will default on. On other operating systems, this
+ will default off, but one may enable this for testing or debugging.
+
``tb-size=n``
Controls the size (in MiB) of the TCG translation block cache.
diff --git a/tcg/aarch64/tcg-target.h b/tcg/aarch64/tcg-target.h
index 5ec30db..23bf87d 100644
--- a/tcg/aarch64/tcg-target.h
+++ b/tcg/aarch64/tcg-target.h
@@ -155,5 +155,6 @@
#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 8d1fee6..494837d 100644
--- a/tcg/arm/tcg-target.h
+++ b/tcg/arm/tcg-target.h
@@ -142,5 +142,6 @@
#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 b693d36..73aa45a 100644
--- a/tcg/i386/tcg-target.h
+++ b/tcg/i386/tcg-target.h
@@ -235,5 +235,6 @@
#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 c2c32fb..fbfe775 100644
--- a/tcg/mips/tcg-target.h
+++ b/tcg/mips/tcg-target.h
@@ -201,6 +201,7 @@
#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 d1339af..ba61a31 100644
--- a/tcg/ppc/tcg-target.h
+++ b/tcg/ppc/tcg-target.h
@@ -185,5 +185,6 @@
#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 727c8df..6263af4 100644
--- a/tcg/riscv/tcg-target.h
+++ b/tcg/riscv/tcg-target.h
@@ -171,5 +171,6 @@
#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 641464e..b8f4296 100644
--- a/tcg/s390/tcg-target.h
+++ b/tcg/s390/tcg-target.h
@@ -159,5 +159,6 @@
#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 95ab9af..6f6cefa 100644
--- a/tcg/sparc/tcg-target.h
+++ b/tcg/sparc/tcg-target.h
@@ -172,5 +172,6 @@
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 bb784e0..d8c78d1 100644
--- a/tcg/tci/tcg-target.h
+++ b/tcg/tci/tcg-target.h
@@ -198,6 +198,7 @@
#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)
