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Add support for pthread_getattr_np #470

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merged 1 commit into from
Mar 11, 2024
Merged

Add support for pthread_getattr_np #470

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1 change: 1 addition & 0 deletions Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -258,6 +258,7 @@ LIBC_TOP_HALF_MUSL_SOURCES += \
thread/pthread_create.c \
thread/pthread_detach.c \
thread/pthread_equal.c \
thread/pthread_getattr_np.c \
thread/pthread_getspecific.c \
thread/pthread_join.c \
thread/pthread_key_create.c \
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1 change: 1 addition & 0 deletions expected/wasm32-wasip1-threads/defined-symbols.txt
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Expand Up @@ -1010,6 +1010,7 @@ pthread_condattr_setpshared
pthread_create
pthread_detach
pthread_equal
pthread_getattr_np
pthread_getspecific
pthread_join
pthread_key_create
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36 changes: 26 additions & 10 deletions libc-top-half/musl/src/env/__init_tls.c
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Expand Up @@ -31,25 +31,35 @@ extern unsigned char __global_base;
extern weak unsigned char __stack_high;
extern weak unsigned char __stack_low;

static inline void setup_default_stack_size()
struct stack_bounds {
void *base;
size_t size;
};

static inline struct stack_bounds get_stack_bounds()
{
ptrdiff_t stack_size;
struct stack_bounds bounds;

if (&__stack_high)
stack_size = &__stack_high - &__stack_low;
else {
if (&__stack_high) {
bounds.base = &__stack_high;
bounds.size = &__stack_high - &__stack_low;
} else {
unsigned char *sp;
__asm__(
".globaltype __stack_pointer, i32\n"
"global.get __stack_pointer\n"
"local.set %0\n"
: "=r"(sp));
stack_size = sp > &__global_base ? &__heap_base - &__data_end : (ptrdiff_t)&__global_base;
if (sp > &__global_base) {
bounds.base = &__heap_base;
bounds.size = &__heap_base - &__data_end;
} else {
bounds.base = &__global_base;
bounds.size = (size_t)&__global_base;
}
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This code only calculates the stack found of the main thread (i.e. the singular stack that the linker produces). Is that intended?

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This fills data for main thread, spawned threads have these fields filled in pthread_create.

}

__default_stacksize =
stack_size < DEFAULT_STACK_MAX ?
stack_size : DEFAULT_STACK_MAX;
return bounds;
}

void __wasi_init_tp() {
Expand All @@ -68,8 +78,14 @@ int __init_tp(void *p)
td->detach_state = DT_JOINABLE;
td->tid = __syscall(SYS_set_tid_address, &__thread_list_lock);
#else
setup_default_stack_size();
struct stack_bounds bounds = get_stack_bounds();
__default_stacksize =
bounds.size < DEFAULT_STACK_MAX ?
bounds.size : DEFAULT_STACK_MAX;
td->detach_state = DT_JOINABLE;
td->stack = bounds.base;
td->stack_size = bounds.size;
td->guard_size = 0;
/*
* Initialize the TID to a value which doesn't conflict with
* host-allocated TIDs, so that TID-based locks can work.
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6 changes: 6 additions & 0 deletions libc-top-half/musl/src/thread/pthread_getattr_np.c
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@@ -1,7 +1,9 @@
#define _GNU_SOURCE
#include "pthread_impl.h"
#include "libc.h"
#ifdef __wasilibc_unmodified_upstream
#include <sys/mman.h>
#endif

int pthread_getattr_np(pthread_t t, pthread_attr_t *a)
{
Expand All @@ -12,13 +14,17 @@ int pthread_getattr_np(pthread_t t, pthread_attr_t *a)
a->_a_stackaddr = (uintptr_t)t->stack;
a->_a_stacksize = t->stack_size;
} else {
#ifdef __wasilibc_unmodified_upstream
char *p = (void *)libc.auxv;
size_t l = PAGE_SIZE;
p += -(uintptr_t)p & PAGE_SIZE-1;
a->_a_stackaddr = (uintptr_t)p;
while (mremap(p-l-PAGE_SIZE, PAGE_SIZE, 2*PAGE_SIZE, 0)==MAP_FAILED && errno==ENOMEM)
l += PAGE_SIZE;
a->_a_stacksize = l;
#else
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Perhaps we can leave the if / else above and just replace the else block.

It looks like that if block covers secondary threads and the else block covers the main thread? We could use the __stack_high / __stack_low globals for the else case I think?

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The idea was to fill these fields in main thread struct and handle everything the same way. Otherwise this would need to duplicate the logic for getting stack bounds, fallback to __heap_base, etc...

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Replaced only else block.

return ENOSYS;
#endif
}
return 0;
}