accel/tcg: Support split-wx for darwin/iOS with vm_remap

Cribbed from code posted by Joelle van Dyne <j@getutm.app>,
and rearranged to a cleaner structure.

Reviewed-by: Joelle van Dyne <j@getutm.app>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2020-10-29 23:49:57 +00:00
parent a8c35b2cad
commit 6f70ddee19

View File

@ -1166,9 +1166,71 @@ static bool alloc_code_gen_buffer_splitwx_memfd(size_t size, Error **errp)
}
#endif /* CONFIG_POSIX */
#ifdef CONFIG_DARWIN
#include <mach/mach.h>
extern kern_return_t mach_vm_remap(vm_map_t target_task,
mach_vm_address_t *target_address,
mach_vm_size_t size,
mach_vm_offset_t mask,
int flags,
vm_map_t src_task,
mach_vm_address_t src_address,
boolean_t copy,
vm_prot_t *cur_protection,
vm_prot_t *max_protection,
vm_inherit_t inheritance);
static bool alloc_code_gen_buffer_splitwx_vmremap(size_t size, Error **errp)
{
kern_return_t ret;
mach_vm_address_t buf_rw, buf_rx;
vm_prot_t cur_prot, max_prot;
/* Map the read-write portion via normal anon memory. */
if (!alloc_code_gen_buffer_anon(size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, errp)) {
return false;
}
buf_rw = (mach_vm_address_t)tcg_ctx->code_gen_buffer;
buf_rx = 0;
ret = mach_vm_remap(mach_task_self(),
&buf_rx,
size,
0,
VM_FLAGS_ANYWHERE,
mach_task_self(),
buf_rw,
false,
&cur_prot,
&max_prot,
VM_INHERIT_NONE);
if (ret != KERN_SUCCESS) {
/* TODO: Convert "ret" to a human readable error message. */
error_setg(errp, "vm_remap for jit splitwx failed");
munmap((void *)buf_rw, size);
return false;
}
if (mprotect((void *)buf_rx, size, PROT_READ | PROT_EXEC) != 0) {
error_setg_errno(errp, errno, "mprotect for jit splitwx");
munmap((void *)buf_rx, size);
munmap((void *)buf_rw, size);
return false;
}
tcg_splitwx_diff = buf_rx - buf_rw;
return true;
}
#endif /* CONFIG_DARWIN */
static bool alloc_code_gen_buffer_splitwx(size_t size, Error **errp)
{
if (TCG_TARGET_SUPPORT_MIRROR) {
#ifdef CONFIG_DARWIN
return alloc_code_gen_buffer_splitwx_vmremap(size, errp);
#endif
#ifdef CONFIG_POSIX
return alloc_code_gen_buffer_splitwx_memfd(size, errp);
#endif
@ -1201,6 +1263,11 @@ static bool alloc_code_gen_buffer(size_t size, int splitwx, Error **errp)
#ifdef CONFIG_TCG_INTERPRETER
/* The tcg interpreter does not need execute permission. */
prot = PROT_READ | PROT_WRITE;
#elif defined(CONFIG_DARWIN)
/* Applicable to both iOS and macOS (Apple Silicon). */
if (!splitwx) {
flags |= MAP_JIT;
}
#endif
return alloc_code_gen_buffer_anon(size, prot, flags, errp);