mirror_zfs/config/kernel-fpu.m4
Attila Fülöp 8e94ac0e36
Linux 5.16 compat: don't use XSTATE_XSAVE to save FPU state
Linux 5.16 moved XSTATE_XSAVE and XSTATE_XRESTORE out of our reach,
so add our own XSAVE{,OPT,S} code and use it for Linux 5.16.

Please note that this differs from previous behavior in that it
won't handle exceptions created by XSAVE an XRSTOR. This is sensible
for three reasons.

 - Exceptions during XSAVE and XRSTOR can only occur if the feature
   is not supported or enabled or the memory operand isn't aligned
   on a 64 byte boundary. If this happens something else went
   terribly wrong, and it may be better to stop execution.

 - Previously we just printed a warning and didn't handle the fault,
   this is arguable for the above reason.

 - All other *SAVE instruction also don't handle exceptions, so this
   at least aligns behavior.

Finally add a test to catch such a regression in the future.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Attila Fülöp <attila@fueloep.org>
Closes #13042
Closes #13059
2022-02-09 12:50:10 -08:00

186 lines
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dnl #
dnl # Handle differences in kernel FPU code.
dnl #
dnl # Kernel
dnl # 5.16: XCR code put into asm/fpu/xcr.h
dnl # HAVE_KERNEL_FPU_XCR_HEADER
dnl #
dnl # XSTATE_XSAVE and XSTATE_XRESTORE aren't accessible any more
dnl # HAVE_KERNEL_FPU_XSAVE_INTERNAL
dnl #
dnl # 5.0: Wrappers have been introduced to save/restore the FPU state.
dnl # This change was made to the 4.19.38 and 4.14.120 LTS kernels.
dnl # HAVE_KERNEL_FPU_INTERNAL
dnl #
dnl # 4.2: Use __kernel_fpu_{begin,end}()
dnl # HAVE_UNDERSCORE_KERNEL_FPU & KERNEL_EXPORTS_X86_FPU
dnl #
dnl # Pre-4.2: Use kernel_fpu_{begin,end}()
dnl # HAVE_KERNEL_FPU & KERNEL_EXPORTS_X86_FPU
dnl #
dnl # N.B. The header check is performed before all other checks since it
dnl # depends on HAVE_KERNEL_FPU_API_HEADER being set in confdefs.h.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_FPU_HEADER], [
AC_MSG_CHECKING([whether fpu headers are available])
ZFS_LINUX_TRY_COMPILE([
#include <linux/module.h>
#include <asm/fpu/api.h>
],[
],[
AC_DEFINE(HAVE_KERNEL_FPU_API_HEADER, 1,
[kernel has asm/fpu/api.h])
AC_MSG_RESULT(asm/fpu/api.h)
AC_MSG_CHECKING([whether fpu/xcr header is available])
ZFS_LINUX_TRY_COMPILE([
#include <linux/module.h>
#include <asm/fpu/xcr.h>
],[
],[
AC_DEFINE(HAVE_KERNEL_FPU_XCR_HEADER, 1,
[kernel has asm/fpu/xcr.h])
AC_MSG_RESULT(asm/fpu/xcr.h)
],[
AC_MSG_RESULT(no asm/fpu/xcr.h)
])
],[
AC_MSG_RESULT(i387.h & xcr.h)
])
])
AC_DEFUN([ZFS_AC_KERNEL_SRC_FPU], [
ZFS_LINUX_TEST_SRC([kernel_fpu], [
#include <linux/types.h>
#ifdef HAVE_KERNEL_FPU_API_HEADER
#include <asm/fpu/api.h>
#else
#include <asm/i387.h>
#include <asm/xcr.h>
#endif
], [
kernel_fpu_begin();
kernel_fpu_end();
], [], [ZFS_META_LICENSE])
ZFS_LINUX_TEST_SRC([__kernel_fpu], [
#include <linux/types.h>
#ifdef HAVE_KERNEL_FPU_API_HEADER
#include <asm/fpu/api.h>
#else
#include <asm/i387.h>
#include <asm/xcr.h>
#endif
], [
__kernel_fpu_begin();
__kernel_fpu_end();
], [], [ZFS_META_LICENSE])
ZFS_LINUX_TEST_SRC([fpu_internal], [
#if defined(__x86_64) || defined(__x86_64__) || \
defined(__i386) || defined(__i386__)
#if !defined(__x86)
#define __x86
#endif
#endif
#if !defined(__x86)
#error Unsupported architecture
#endif
#include <linux/types.h>
#ifdef HAVE_KERNEL_FPU_API_HEADER
#include <asm/fpu/api.h>
#include <asm/fpu/internal.h>
#else
#include <asm/i387.h>
#include <asm/xcr.h>
#endif
#if !defined(XSTATE_XSAVE)
#error XSTATE_XSAVE not defined
#endif
#if !defined(XSTATE_XRESTORE)
#error XSTATE_XRESTORE not defined
#endif
],[
struct fpu *fpu = &current->thread.fpu;
union fpregs_state *st = &fpu->state;
struct fregs_state *fr __attribute__ ((unused)) = &st->fsave;
struct fxregs_state *fxr __attribute__ ((unused)) = &st->fxsave;
struct xregs_state *xr __attribute__ ((unused)) = &st->xsave;
])
ZFS_LINUX_TEST_SRC([fpu_xsave_internal], [
#include <linux/sched.h>
#if defined(__x86_64) || defined(__x86_64__) || \
defined(__i386) || defined(__i386__)
#if !defined(__x86)
#define __x86
#endif
#endif
#if !defined(__x86)
#error Unsupported architecture
#endif
#include <linux/types.h>
#ifdef HAVE_KERNEL_FPU_API_HEADER
#include <asm/fpu/api.h>
#include <asm/fpu/internal.h>
#else
#include <asm/i387.h>
#include <asm/xcr.h>
#endif
],[
struct fpu *fpu = &current->thread.fpu;
union fpregs_state *st = &fpu->fpstate->regs;
struct fregs_state *fr __attribute__ ((unused)) = &st->fsave;
struct fxregs_state *fxr __attribute__ ((unused)) = &st->fxsave;
struct xregs_state *xr __attribute__ ((unused)) = &st->xsave;
])
])
AC_DEFUN([ZFS_AC_KERNEL_FPU], [
dnl #
dnl # Legacy kernel
dnl #
AC_MSG_CHECKING([whether kernel fpu is available])
ZFS_LINUX_TEST_RESULT_SYMBOL([kernel_fpu_license],
[kernel_fpu_begin], [arch/x86/kernel/fpu/core.c], [
AC_MSG_RESULT(kernel_fpu_*)
AC_DEFINE(HAVE_KERNEL_FPU, 1,
[kernel has kernel_fpu_* functions])
AC_DEFINE(KERNEL_EXPORTS_X86_FPU, 1,
[kernel exports FPU functions])
],[
dnl #
dnl # Linux 4.2 kernel
dnl #
ZFS_LINUX_TEST_RESULT_SYMBOL([__kernel_fpu_license],
[__kernel_fpu_begin],
[arch/x86/kernel/fpu/core.c arch/x86/kernel/i387.c], [
AC_MSG_RESULT(__kernel_fpu_*)
AC_DEFINE(HAVE_UNDERSCORE_KERNEL_FPU, 1,
[kernel has __kernel_fpu_* functions])
AC_DEFINE(KERNEL_EXPORTS_X86_FPU, 1,
[kernel exports FPU functions])
],[
ZFS_LINUX_TEST_RESULT([fpu_internal], [
AC_MSG_RESULT(internal)
AC_DEFINE(HAVE_KERNEL_FPU_INTERNAL, 1,
[kernel fpu internal])
],[
ZFS_LINUX_TEST_RESULT([fpu_xsave_internal], [
AC_MSG_RESULT(internal with internal XSAVE)
AC_DEFINE(HAVE_KERNEL_FPU_XSAVE_INTERNAL, 1,
[kernel fpu and XSAVE internal])
],[
AC_MSG_RESULT(unavailable)
])
])
])
])
])