https://github.com/python/cpython/commit/7094f09f547dc1a520c666dc6ce11b7b69a1b8da
commit: 7094f09f547dc1a520c666dc6ce11b7b69a1b8da
branch: main
author: Mark Shannon <[email protected]>
committer: encukou <[email protected]>
date: 2025-10-07T15:04:37+02:00
summary:
GH-139291: Fix C stack limits by factoring out finding hardware stack limits
(GH-139294)
files:
M Python/ceval.c
diff --git a/Python/ceval.c b/Python/ceval.c
index 0ccaacaf3ed5b1..1b52128c858ecb 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -438,31 +438,26 @@ int pthread_attr_destroy(pthread_attr_t *a)
#endif
-
-void
-_Py_InitializeRecursionLimits(PyThreadState *tstate)
+static void
+hardware_stack_limits(uintptr_t *top, uintptr_t *base)
{
- _PyThreadStateImpl *_tstate = (_PyThreadStateImpl *)tstate;
#ifdef WIN32
ULONG_PTR low, high;
GetCurrentThreadStackLimits(&low, &high);
- _tstate->c_stack_top = (uintptr_t)high;
+ *top = (uintptr_t)high;
ULONG guarantee = 0;
SetThreadStackGuarantee(&guarantee);
- _tstate->c_stack_hard_limit = ((uintptr_t)low) + guarantee +
_PyOS_STACK_MARGIN_BYTES;
- _tstate->c_stack_soft_limit = _tstate->c_stack_hard_limit +
_PyOS_STACK_MARGIN_BYTES;
+ *base = (uintptr_t)low + guarantee;
#elif defined(__APPLE__)
pthread_t this_thread = pthread_self();
void *stack_addr = pthread_get_stackaddr_np(this_thread); // top of the
stack
size_t stack_size = pthread_get_stacksize_np(this_thread);
- _tstate->c_stack_top = (uintptr_t)stack_addr;
- _tstate->c_stack_hard_limit = _tstate->c_stack_top - stack_size;
- _tstate->c_stack_soft_limit = _tstate->c_stack_hard_limit +
_PyOS_STACK_MARGIN_BYTES;
+ *top = (uintptr_t)stack_addr;
+ *base = ((uintptr_t)stack_addr) - stack_size;
#else
- uintptr_t here_addr = _Py_get_machine_stack_pointer();
-/// XXX musl supports HAVE_PTHRED_GETATTR_NP, but the resulting stack size
-/// (on alpine at least) is much smaller than expected and imposes undue limits
-/// compared to the old stack size estimation. (We assume musl is not glibc.)
+ /// XXX musl supports HAVE_PTHRED_GETATTR_NP, but the resulting stack size
+ /// (on alpine at least) is much smaller than expected and imposes undue
limits
+ /// compared to the old stack size estimation. (We assume musl is not
glibc.)
# if defined(HAVE_PTHREAD_GETATTR_NP) && !defined(_AIX) && \
!defined(__NetBSD__) && (defined(__GLIBC__) || !defined(__linux__))
size_t stack_size, guard_size;
@@ -475,26 +470,35 @@ _Py_InitializeRecursionLimits(PyThreadState *tstate)
err |= pthread_attr_destroy(&attr);
}
if (err == 0) {
- uintptr_t base = ((uintptr_t)stack_addr) + guard_size;
- _tstate->c_stack_top = base + stack_size;
-#ifdef _Py_THREAD_SANITIZER
- // Thread sanitizer crashes if we use a bit more than half the stack.
- _tstate->c_stack_soft_limit = base + (stack_size / 2);
-#else
- _tstate->c_stack_soft_limit = base + _PyOS_STACK_MARGIN_BYTES * 2;
-#endif
- _tstate->c_stack_hard_limit = base + _PyOS_STACK_MARGIN_BYTES;
- assert(_tstate->c_stack_soft_limit < here_addr);
- assert(here_addr < _tstate->c_stack_top);
+ *base = ((uintptr_t)stack_addr) + guard_size;
+ *top = (uintptr_t)stack_addr + stack_size;
return;
}
# endif
- _tstate->c_stack_top = _Py_SIZE_ROUND_UP(here_addr, 4096);
- _tstate->c_stack_soft_limit = _tstate->c_stack_top - Py_C_STACK_SIZE;
- _tstate->c_stack_hard_limit = _tstate->c_stack_top - (Py_C_STACK_SIZE +
_PyOS_STACK_MARGIN_BYTES);
+ uintptr_t here_addr = _Py_get_machine_stack_pointer();
+ uintptr_t top_addr = _Py_SIZE_ROUND_UP(here_addr, 4096);
+ *top = top_addr;
+ *base = top_addr - Py_C_STACK_SIZE;
#endif
}
+void
+_Py_InitializeRecursionLimits(PyThreadState *tstate)
+{
+ uintptr_t top;
+ uintptr_t base;
+ hardware_stack_limits(&top, &base);
+#ifdef _Py_THREAD_SANITIZER
+ // Thread sanitizer crashes if we use more than half the stack.
+ uintptr_t stacksize = top - base;
+ base += stacksize/2;
+#endif
+ _PyThreadStateImpl *_tstate = (_PyThreadStateImpl *)tstate;
+ _tstate->c_stack_top = top;
+ _tstate->c_stack_hard_limit = base + _PyOS_STACK_MARGIN_BYTES;
+ _tstate->c_stack_soft_limit = base + _PyOS_STACK_MARGIN_BYTES * 2;
+}
+
/* The function _Py_EnterRecursiveCallTstate() only calls
_Py_CheckRecursiveCall()
if the recursion_depth reaches recursion_limit. */
int
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