commit 5044c889dfced2f43e2cccb673d889a4882f6b3b

Author: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>

Date:   Wed Dec 4 12:29:22 2019 -0800

    bpo-38965: Fix faulthandler._stack_overflow() on GCC 10 (GH-17467)

    Use the "volatile" keyword to prevent tail call optimization

    on any compiler, rather than relying on compiler specific pragma.

    (cherry picked from commit 8b787964e0a647caa0558b7c29ae501470d727d9)

    Co-authored-by: Victor Stinner <vstinner@python.org>

commit ac827edc493d3ac3f5b9b0cc353df1d4b418a9aa

Author: Victor Stinner <vstinner@redhat.com>

Date:   Wed Aug 14 23:35:27 2019 +0200

    bpo-21131: Fix faulthandler.register(chain=True) stack (GH-15276)

    faulthandler now allocates a dedicated stack of SIGSTKSZ*2 bytes,

    instead of just SIGSTKSZ bytes. Calling the previous signal handler

    in faulthandler signal handler uses more than SIGSTKSZ bytes of stack

    memory on some platforms.

diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c

index 890c645..fac662a 100644

--- a/Modules/faulthandler.c

+++ b/Modules/faulthandler.c

@@ -1091,18 +1091,14 @@ faulthandler_fatal_error_py(PyObject *self, PyObject *args)

 #if defined(HAVE_SIGALTSTACK) && defined(HAVE_SIGACTION)

 #define FAULTHANDLER_STACK_OVERFLOW

-#ifdef __INTEL_COMPILER

-   /* Issue #23654: Turn off ICC's tail call optimization for the

-    * stack_overflow generator. ICC turns the recursive tail call into

-    * a loop. */

-#  pragma intel optimization_level 0

-#endif

-static

-uintptr_t

+static uintptr_t

 stack_overflow(uintptr_t min_sp, uintptr_t max_sp, size_t *depth)

 {

-    /* allocate 4096 bytes on the stack at each call */

-    unsigned char buffer[4096];

+    /* Allocate (at least) 4096 bytes on the stack at each call.

+

+       bpo-23654, bpo-38965: use volatile keyword to prevent tail call

+       optimization. */

+    volatile unsigned char buffer[4096];

     uintptr_t sp = (uintptr_t)&buffer;

     *depth += 1;

     if (sp < min_sp || max_sp < sp)

@@ -1333,7 +1329,11 @@ int _PyFaulthandler_Init(void)

      * be able to allocate memory on the stack, even on a stack overflow. If it

      * fails, ignore the error. */

     stack.ss_flags = 0;

-    stack.ss_size = SIGSTKSZ;

+    /* bpo-21131: allocate dedicated stack of SIGSTKSZ*2 bytes, instead of just

+       SIGSTKSZ bytes. Calling the previous signal handler in faulthandler

+       signal handler uses more than SIGSTKSZ bytes of stack memory on some

+       platforms. */

+    stack.ss_size = SIGSTKSZ * 2;

     stack.ss_sp = PyMem_Malloc(stack.ss_size);

     if (stack.ss_sp != NULL) {

         err = sigaltstack(&stack, &old_stack);