From: John Paul Adrian Glaubitz Date: Tue, 9 Dec 2025 13:46:40 +0000 (+0100) Subject: gh-142342: Fix m68k assembler operand constraints for `%fpcr` access (gh-142343) X-Git-Tag: v3.15.0a3~144 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=02c085d48b59c00fb7f4454fb13933e1c2c0b01a;p=thirdparty%2FPython%2Fcpython.git gh-142342: Fix m68k assembler operand constraints for `%fpcr` access (gh-142343) On m68k, an fmove instruction accessing %fpcr may only move from or to a data register or a memory operand. The constraint "g" also permits the use of address registers, which is invalid. The correct constraint is "dm". Beginning with GCC 15, the register allocator picks an address register in the code which causes SIGILL during runtime. Co-authored-by: Michael Karcher --- diff --git a/Include/internal/pycore_pymath.h b/Include/internal/pycore_pymath.h index 4fcac3aab8bf..f66325aa59c4 100644 --- a/Include/internal/pycore_pymath.h +++ b/Include/internal/pycore_pymath.h @@ -146,17 +146,17 @@ extern void _Py_set_387controlword(unsigned short); unsigned int old_fpcr, new_fpcr #define _Py_SET_53BIT_PRECISION_START \ do { \ - __asm__ ("fmove.l %%fpcr,%0" : "=g" (old_fpcr)); \ + __asm__ ("fmove.l %%fpcr,%0" : "=dm" (old_fpcr)); \ /* Set double precision / round to nearest. */ \ new_fpcr = (old_fpcr & ~0xf0) | 0x80; \ if (new_fpcr != old_fpcr) { \ - __asm__ volatile ("fmove.l %0,%%fpcr" : : "g" (new_fpcr));\ + __asm__ volatile ("fmove.l %0,%%fpcr" : : "dm" (new_fpcr)); \ } \ } while (0) #define _Py_SET_53BIT_PRECISION_END \ do { \ if (new_fpcr != old_fpcr) { \ - __asm__ volatile ("fmove.l %0,%%fpcr" : : "g" (old_fpcr)); \ + __asm__ volatile ("fmove.l %0,%%fpcr" : : "dm" (old_fpcr)); \ } \ } while (0) #endif diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-12-08-13-04-37.gh-issue-142343.BTAyML.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-12-08-13-04-37.gh-issue-142343.BTAyML.rst new file mode 100644 index 000000000000..9da936c2a6f3 --- /dev/null +++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-12-08-13-04-37.gh-issue-142343.BTAyML.rst @@ -0,0 +1 @@ +Fix SIGILL crash on m68k due to incorrect assembly constraint. diff --git a/configure b/configure index 4f9b9b21ca39..2fe8186d9fb5 100755 --- a/configure +++ b/configure @@ -26139,8 +26139,8 @@ main (void) { unsigned int fpcr; - __asm__ __volatile__ ("fmove.l %%fpcr,%0" : "=g" (fpcr)); - __asm__ __volatile__ ("fmove.l %0,%%fpcr" : : "g" (fpcr)); + __asm__ __volatile__ ("fmove.l %%fpcr,%0" : "=dm" (fpcr)); + __asm__ __volatile__ ("fmove.l %0,%%fpcr" : : "dm" (fpcr)); ; return 0; diff --git a/configure.ac b/configure.ac index 046c046ffb5d..25a00ce52e57 100644 --- a/configure.ac +++ b/configure.ac @@ -6133,8 +6133,8 @@ AS_VAR_IF([ac_cv_gcc_asm_for_x87], [yes], [ AC_CACHE_CHECK([whether we can use gcc inline assembler to get and set mc68881 fpcr], [ac_cv_gcc_asm_for_mc68881], [ AC_LINK_IFELSE( [AC_LANG_PROGRAM([[]], [[ unsigned int fpcr; - __asm__ __volatile__ ("fmove.l %%fpcr,%0" : "=g" (fpcr)); - __asm__ __volatile__ ("fmove.l %0,%%fpcr" : : "g" (fpcr)); + __asm__ __volatile__ ("fmove.l %%fpcr,%0" : "=dm" (fpcr)); + __asm__ __volatile__ ("fmove.l %0,%%fpcr" : : "dm" (fpcr)); ]])],[ac_cv_gcc_asm_for_mc68881=yes],[ac_cv_gcc_asm_for_mc68881=no]) ]) AS_VAR_IF([ac_cv_gcc_asm_for_mc68881], [yes], [