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bpo-46968: Fix faulthandler for Sapphire Rapids Xeon (GH-31789)

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In Linux kernel 5.14 one can dynamically request size of altstacksize
based on hardware capabilities with getauxval(AT_MINSIGSTKSZ).

This changes allows for Python extension's request to Linux kernel
to use AMX_TILE instruction set on Sapphire Rapids Xeon processor
to succeed, unblocking use of the ISA in frameworks.

Introduced HAVE_LINUX_AUXVEC_H in configure.ac and pyconfig.h.in
Used cpython_autoconf:269 docker container to generate configure.
This commit is contained in:
Oleksandr Pavlyk 2022-03-11 16:19:35 -06:00 • committed by GitHub
parent dc374ac7b0
commit 3b128c0548
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 30 additions and 8 deletions
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26
Modules/faulthandler.c
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@ -20,6 +20,17 @@
# include <sys/resource.h>
#endif
/* Using an alternative stack requires sigaltstack()
and sigaction() SA_ONSTACK */
#if defined(HAVE_SIGALTSTACK) && defined(HAVE_SIGACTION)
# define FAULTHANDLER_USE_ALT_STACK
#endif
#if defined(FAULTHANDLER_USE_ALT_STACK) && defined(HAVE_LINUX_AUXVEC_H)
# include <linux/auxvec.h>
# include <sys/auxv.h>
#endif
/* Allocate at maximum 100 MiB of the stack to raise the stack overflow */
#define STACK_OVERFLOW_MAX_SIZE (100 * 1024 * 1024)
@ -137,12 +148,6 @@ static fault_handler_t faulthandler_handlers[] = {
static const size_t faulthandler_nsignals = \
Py_ARRAY_LENGTH(faulthandler_handlers);
/* Using an alternative stack requires sigaltstack()
and sigaction() SA_ONSTACK */
#if defined(HAVE_SIGALTSTACK) && defined(HAVE_SIGACTION)
# define FAULTHANDLER_USE_ALT_STACK
#endif
#ifdef FAULTHANDLER_USE_ALT_STACK
static stack_t stack;
static stack_t old_stack;
@ -1373,6 +1378,15 @@ _PyFaulthandler_Init(int enable)
signal handler uses more than SIGSTKSZ bytes of stack memory on some
platforms. */
stack.ss_size = SIGSTKSZ * 2;
#ifdef AT_MINSIGSTKSZ
/* bpo-46968: Query Linux for minimal stack size to ensure signal delivery
for the hardware running CPython. This OS feature is available in
Linux kernel version >= 5.14 */
unsigned long at_minstack_size = getauxval(AT_MINSIGSTKSZ);
if (at_minstack_size != 0) {
stack.ss_size = SIGSTKSZ + at_minstack_size;
}
#endif
#endif
memset(&thread, 0, sizeof(thread));