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tcg: Return the map protection from alloc_code_gen_buffer
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Change the interface from a boolean error indication to a
negative error vs a non-negative protection.  For the moment
this is only interface change, not making use of the new data.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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@rth7680
rth7680 committed Jun 14, 2021
1 parent 032a4b1 commit 7be9ebc
Showing 1 changed file with 33 additions and 30 deletions.
63 changes: 33 additions & 30 deletions tcg/region.c
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Expand Up @@ -526,14 +526,14 @@ static inline void split_cross_256mb(void **obuf, size_t *osize,
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, int splitwx, Error **errp)
static int alloc_code_gen_buffer(size_t tb_size, int splitwx, Error **errp)
{
void *buf, *end;
size_t size;

if (splitwx > 0) {
error_setg(errp, "jit split-wx not supported");
return false;
return -1;
}

/* page-align the beginning and end of the buffer */
Expand Down Expand Up @@ -563,16 +563,17 @@ static bool alloc_code_gen_buffer(size_t tb_size, int splitwx, Error **errp)

region.start_aligned = buf;
region.total_size = size;
return true;

return PROT_READ | PROT_WRITE;
}
#elif defined(_WIN32)
static bool alloc_code_gen_buffer(size_t size, int splitwx, Error **errp)
static int alloc_code_gen_buffer(size_t size, int splitwx, Error **errp)
{
void *buf;

if (splitwx > 0) {
error_setg(errp, "jit split-wx not supported");
return false;
return -1;
}

buf = VirtualAlloc(NULL, size, MEM_RESERVE | MEM_COMMIT,
Expand All @@ -585,19 +586,20 @@ static bool alloc_code_gen_buffer(size_t size, int splitwx, Error **errp)

region.start_aligned = buf;
region.total_size = size;
return true;

return PAGE_READ | PAGE_WRITE | PAGE_EXEC;
}
#else
static bool alloc_code_gen_buffer_anon(size_t size, int prot,
int flags, Error **errp)
static int alloc_code_gen_buffer_anon(size_t size, int prot,
int flags, Error **errp)
{
void *buf;

buf = mmap(NULL, size, prot, flags, -1, 0);
if (buf == MAP_FAILED) {
error_setg_errno(errp, errno,
"allocate %zu bytes for jit buffer", size);
return false;
return -1;
}

#ifdef __mips__
Expand Down Expand Up @@ -638,7 +640,7 @@ static bool alloc_code_gen_buffer_anon(size_t size, int prot,

region.start_aligned = buf;
region.total_size = size;
return true;
return prot;
}

#ifndef CONFIG_TCG_INTERPRETER
Expand All @@ -652,9 +654,9 @@ static bool alloc_code_gen_buffer_splitwx_memfd(size_t size, Error **errp)

#ifdef __mips__
/* Find space for the RX mapping, vs the 256MiB regions. */
if (!alloc_code_gen_buffer_anon(size, PROT_NONE,
MAP_PRIVATE | MAP_ANONYMOUS |
MAP_NORESERVE, errp)) {
if (alloc_code_gen_buffer_anon(size, PROT_NONE,
MAP_PRIVATE | MAP_ANONYMOUS |
MAP_NORESERVE, errp) < 0) {
return false;
}
/* The size of the mapping may have been adjusted. */
Expand Down Expand Up @@ -688,7 +690,7 @@ static bool alloc_code_gen_buffer_splitwx_memfd(size_t size, Error **errp)
/* Request large pages for the buffer and the splitwx. */
qemu_madvise(buf_rw, size, QEMU_MADV_HUGEPAGE);
qemu_madvise(buf_rx, size, QEMU_MADV_HUGEPAGE);
return true;
return PROT_READ | PROT_WRITE;

fail_rx:
error_setg_errno(errp, errno, "failed to map shared memory for execute");
Expand All @@ -702,7 +704,7 @@ static bool alloc_code_gen_buffer_splitwx_memfd(size_t size, Error **errp)
if (fd >= 0) {
close(fd);
}
return false;
return -1;
}
#endif /* CONFIG_POSIX */

Expand All @@ -721,7 +723,7 @@ extern kern_return_t mach_vm_remap(vm_map_t target_task,
vm_prot_t *max_protection,
vm_inherit_t inheritance);

static bool alloc_code_gen_buffer_splitwx_vmremap(size_t size, Error **errp)
static int alloc_code_gen_buffer_splitwx_vmremap(size_t size, Error **errp)
{
kern_return_t ret;
mach_vm_address_t buf_rw, buf_rx;
Expand All @@ -730,7 +732,7 @@ static bool alloc_code_gen_buffer_splitwx_vmremap(size_t size, Error **errp)
/* 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;
return -1;
}

buf_rw = (mach_vm_address_t)region.start_aligned;
Expand All @@ -750,23 +752,23 @@ static bool alloc_code_gen_buffer_splitwx_vmremap(size_t size, Error **errp)
/* 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;
return -1;
}

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;
return -1;
}

tcg_splitwx_diff = buf_rx - buf_rw;
return true;
return PROT_READ | PROT_WRITE;
}
#endif /* CONFIG_DARWIN */
#endif /* CONFIG_TCG_INTERPRETER */

static bool alloc_code_gen_buffer_splitwx(size_t size, Error **errp)
static int alloc_code_gen_buffer_splitwx(size_t size, Error **errp)
{
#ifndef CONFIG_TCG_INTERPRETER
# ifdef CONFIG_DARWIN
Expand All @@ -777,24 +779,25 @@ static bool alloc_code_gen_buffer_splitwx(size_t size, Error **errp)
# endif
#endif
error_setg(errp, "jit split-wx not supported");
return false;
return -1;
}

static bool alloc_code_gen_buffer(size_t size, int splitwx, Error **errp)
static int alloc_code_gen_buffer(size_t size, int splitwx, Error **errp)
{
ERRP_GUARD();
int prot, flags;

if (splitwx) {
if (alloc_code_gen_buffer_splitwx(size, errp)) {
return true;
prot = alloc_code_gen_buffer_splitwx(size, errp);
if (prot >= 0) {
return prot;
}
/*
* If splitwx force-on (1), fail;
* if splitwx default-on (-1), fall through to splitwx off.
*/
if (splitwx > 0) {
return false;
return -1;
}
error_free_or_abort(errp);
}
Expand Down Expand Up @@ -848,11 +851,11 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus)
size_t page_size;
size_t region_size;
size_t i;
bool ok;
int have_prot;

ok = alloc_code_gen_buffer(size_code_gen_buffer(tb_size),
splitwx, &error_fatal);
assert(ok);
have_prot = alloc_code_gen_buffer(size_code_gen_buffer(tb_size),
splitwx, &error_fatal);
assert(have_prot >= 0);

/*
* Make region_size a multiple of page_size, using aligned as the start.
Expand Down

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