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Use __tdata_align to align thread local storage (#504)

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Ian Chamberlain 2022-09-14 13:26:23 -04:00 committed by GitHub
parent 59cf50c201
commit b20ac22ab7
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 34 additions and 20 deletions
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10
libctru/source/internal.h
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@ -8,6 +8,12 @@
#define THREADVARS_MAGIC 0x21545624 // !TV$ #define THREADVARS_MAGIC 0x21545624 // !TV$
#define FS_OVERRIDE_MAGIC 0x21465324 // !FS$ #define FS_OVERRIDE_MAGIC 0x21465324 // !FS$
extern const size_t __tdata_align;
extern const u8 __tdata_lma[];
extern const u8 __tdata_lma_end[];
extern u8 __tls_start[];
extern u8 __tls_end[];
// Keep this structure under 0x80 bytes // Keep this structure under 0x80 bytes
typedef struct typedef struct
{ {
@ -48,3 +54,7 @@ static inline ThreadVars* getThreadVars(void)
} }
void initThreadVars(struct Thread_tag *thread); void initThreadVars(struct Thread_tag *thread);
static inline size_t alignTo(const size_t base, const size_t align) {
return (base + (align - 1)) & ~(align - 1);
}

11
libctru/source/system/syscalls.c
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@ -16,10 +16,6 @@
void __ctru_exit(int rc); void __ctru_exit(int rc);
extern const u8 __tdata_lma[];
extern const u8 __tdata_lma_end[];
extern u8 __tls_start[];
struct _reent* __SYSCALL(getreent)() struct _reent* __SYSCALL(getreent)()
{ {
ThreadVars* tv = getThreadVars(); ThreadVars* tv = getThreadVars();
@ -43,7 +39,7 @@ int __SYSCALL(clock_gettime)(clockid_t clock_id, struct timespec *tp) {
tp->tv_nsec = (ms_since_epoch % 1000) * 1000000; tp->tv_nsec = (ms_since_epoch % 1000) * 1000000;
} }
} }
else if (clock_id == CLOCK_MONOTONIC) else if (clock_id == CLOCK_MONOTONIC)
{ {
if (tp != NULL) if (tp != NULL)
{ {
@ -66,7 +62,7 @@ int __SYSCALL(clock_gettime)(clockid_t clock_id, struct timespec *tp) {
int __SYSCALL(clock_getres)(clockid_t clock_id, struct timespec *res) { int __SYSCALL(clock_getres)(clockid_t clock_id, struct timespec *res) {
if (clock_id == CLOCK_REALTIME) if (clock_id == CLOCK_REALTIME)
{ {
if (res != NULL) if (res != NULL)
{ {
res->tv_sec = 0; res->tv_sec = 0;
res->tv_nsec = 1000000; res->tv_nsec = 1000000;
@ -185,6 +181,7 @@ void __system_initSyscalls(void)
// Initialize thread vars for the main thread // Initialize thread vars for the main thread
initThreadVars(NULL); initThreadVars(NULL);
u32 tls_size = __tdata_lma_end - __tdata_lma; u32 tls_size = __tdata_lma_end - __tdata_lma;
size_t tdata_start = alignTo((size_t)__tls_start, __tdata_align);
if (tls_size) if (tls_size)
memcpy(__tls_start, __tdata_lma, tls_size); memcpy((void*)tdata_start, __tdata_lma, tls_size);
} }

33
libctru/source/thread.c
View File

@ -3,11 +3,6 @@
#include <malloc.h> #include <malloc.h>
#include <string.h> #include <string.h>
extern const u8 __tdata_lma[];
extern const u8 __tdata_lma_end[];
extern u8 __tls_start[];
extern u8 __tls_end[];
static void __panic(void) static void __panic(void)
{ {
svcBreak(USERBREAK_PANIC); svcBreak(USERBREAK_PANIC);
@ -24,18 +19,26 @@ static void _thread_begin(void* arg)
Thread threadCreate(ThreadFunc entrypoint, void* arg, size_t stack_size, int prio, int core_id, bool detached) Thread threadCreate(ThreadFunc entrypoint, void* arg, size_t stack_size, int prio, int core_id, bool detached)
{ {
size_t stackoffset = (sizeof(struct Thread_tag)+7)&~7; // The stack must be 8-aligned at minimum.
size_t allocsize = stackoffset + ((stack_size+7)&~7); size_t align = __tdata_align > 8 ? __tdata_align : 8;
size_t stackoffset = alignTo(sizeof(struct Thread_tag), align);
size_t allocsize = alignTo(stackoffset + stack_size, align);
size_t tlssize = __tls_end-__tls_start; size_t tlssize = __tls_end-__tls_start;
size_t tlsloadsize = __tdata_lma_end-__tdata_lma; size_t tlsloadsize = __tdata_lma_end-__tdata_lma;
size_t tbsssize = tlssize-tlsloadsize; size_t tbsssize = tlssize - tlsloadsize;
// memalign seems to have an implicit requirement that (size % align) == 0.
// Without this, it seems to return NULL whenever (align > 8).
size_t size = alignTo(allocsize + tlssize, align);
// Guard against overflow // Guard against overflow
if (allocsize < stackoffset) return NULL; if (allocsize < stackoffset) return NULL;
if ((allocsize-stackoffset) < stack_size) return NULL; if ((allocsize - stackoffset) < stack_size) return NULL;
if ((allocsize+tlssize) < allocsize) return NULL; if (size < allocsize) return NULL;
Thread t = (Thread)memalign(8,allocsize+tlssize); Thread t = (Thread)memalign(align, size);
if (!t) return NULL; if (!t) return NULL;
t->ep = entrypoint; t->ep = entrypoint;
@ -44,10 +47,14 @@ Thread threadCreate(ThreadFunc entrypoint, void* arg, size_t stack_size, int pri
t->finished = false; t->finished = false;
t->stacktop = (u8*)t + allocsize; t->stacktop = (u8*)t + allocsize;
// ThreadVars.tls_tp must be aligned correctly, so we bump tdata_start to
// ensure that after subtracting 8 bytes for the TLS header, it will be aligned.
size_t tdata_start = 8 + alignTo((size_t)t->stacktop - 8, align);
if (tlsloadsize) if (tlsloadsize)
memcpy(t->stacktop, __tdata_lma, tlsloadsize); memcpy((void*)tdata_start, __tdata_lma, tlsloadsize);
if (tbsssize) if (tbsssize)
memset((u8*)t->stacktop+tlsloadsize, 0, tbsssize); memset((void*)tdata_start + tlsloadsize, 0, tbsssize);
// Set up child thread's reent struct, inheriting standard file handles // Set up child thread's reent struct, inheriting standard file handles
_REENT_INIT_PTR(&t->reent); _REENT_INIT_PTR(&t->reent);