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2021-10-21x86/fpu: Add size and mask information to fpstateThomas Gleixner
Add state size and feature mask information to the fpstate container. This will be used for runtime checks with the upcoming support for dynamically enabled features and dynamically sized buffers. That avoids conditionals all over the place as the required information is accessible for both default and extended buffers. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211013145322.921388806@linutronix.de
2021-10-21x86/process: Move arch_thread_struct_whitelist() out of lineThomas Gleixner
In preparation for dynamically enabled FPU features move the function out of line as the goal is to expose less and not more information. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211013145322.869001791@linutronix.de
2021-10-20x86/fpu: Remove fpu::stateThomas Gleixner
All users converted. Remove it along with the sanity checks. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211013145322.765063318@linutronix.de
2021-10-20x86/fpu/core: Convert to fpstateThomas Gleixner
Convert the rest of the core code to the new register storage mechanism in preparation for dynamically sized buffers. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211013145322.659456185@linutronix.de
2021-10-20x86/fpu/signal: Convert to fpstateThomas Gleixner
Convert signal related code to the new register storage mechanism in preparation for dynamically sized buffers. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211013145322.607370221@linutronix.de
2021-10-20x86/fpu/regset: Convert to fpstateThomas Gleixner
Convert regset related code to the new register storage mechanism in preparation for dynamically sized buffers. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211013145322.555239736@linutronix.de
2021-10-20x86/fpu: Replace KVMs xstate component clearingThomas Gleixner
In order to prepare for the support of dynamically enabled FPU features, move the clearing of xstate components to the FPU core code. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: kvm@vger.kernel.org Link: https://lkml.kernel.org/r/20211013145322.399567049@linutronix.de
2021-10-20x86/fpu: Convert restore_fpregs_from_fpstate() to struct fpstateThomas Gleixner
Convert restore_fpregs_from_fpstate() and related code to the new register storage mechanism in preparation for dynamically sized buffers. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211013145322.347395546@linutronix.de
2021-10-20x86/fpu: Convert fpstate_init() to struct fpstateThomas Gleixner
Convert fpstate_init() and related code to the new register storage mechanism in preparation for dynamically sized buffers. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211013145322.292157401@linutronix.de
2021-10-20x86/fpu: Provide struct fpstateThomas Gleixner
New xfeatures will not longer be automatically stored in the regular XSAVE buffer in thread_struct::fpu. The kernel will provide the default sized buffer for storing the regular features up to AVX512 in thread_struct::fpu and if a task requests to use one of the new features then the register storage has to be extended. The state will be accessed via a pointer in thread_struct::fpu which defaults to the builtin storage and can be switched when extended storage is required. To avoid conditionals all over the code, create a new container for the register storage which will gain other information, e.g. size, feature masks etc., later. For now it just contains the register storage, which gives it exactly the same layout as the exiting fpu::state. Stick fpu::state and the new fpu::__fpstate into an anonymous union and initialize the pointer. Add build time checks to validate that both are at the same place and have the same size. This allows step by step conversion of all users. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211013145322.234458659@linutronix.de
2021-10-20x86/fpu: Replace KVMs home brewed FPU copy to userThomas Gleixner
Similar to the copy from user function the FPU core has this already implemented with all bells and whistles. Get rid of the duplicated code and use the core functionality. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: kvm@vger.kernel.org Link: https://lkml.kernel.org/r/20211015011539.244101845@linutronix.de
2021-10-20x86/fpu: Provide a proper function for ex_handler_fprestore()Thomas Gleixner
To make upcoming changes for support of dynamically enabled features simpler, provide a proper function for the exception handler which removes exposure of FPU internals. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011540.053515012@linutronix.de
2021-10-20x86/fpu: Replace the includes of fpu/internal.hThomas Gleixner
Now that the file is empty, fixup all references with the proper includes and delete the former kitchen sink. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011540.001197214@linutronix.de
2021-10-20x86/fpu: Mop up the internal.h leftoversThomas Gleixner
Move the global interfaces to api.h and the rest into the core. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.948837194@linutronix.de
2021-10-20x86/fpu: Remove internal.h dependency from fpu/signal.hThomas Gleixner
In order to remove internal.h make signal.h independent of it. Include asm/fpu/xstate.h to fix a missing update_regset_xstate_info() prototype, which is Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.844565975@linutronix.de
2021-10-20x86/fpu: Move fpstate functions to api.hThomas Gleixner
Move function declarations which need to be globally available to api.h where they belong. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.792363754@linutronix.de
2021-10-20x86/fpu: Move mxcsr related code to coreThomas Gleixner
No need to expose that to code which only needs the XCR0 accessors. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.740012411@linutronix.de
2021-10-20x86/fpu: Move fpregs_restore_userregs() to coreThomas Gleixner
Only used internally in the FPU core code. While at it, convert to the percpu accessors which verify preemption is disabled. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.686806639@linutronix.de
2021-10-20x86/fpu: Make WARN_ON_FPU() privateThomas Gleixner
No point in being in global headers. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.628516182@linutronix.de
2021-10-20x86/fpu: Move legacy ASM wrappers to coreThomas Gleixner
Nothing outside the core code requires them. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.572439164@linutronix.de
2021-10-20x86/fpu: Move os_xsave() and os_xrstor() to coreThomas Gleixner
Nothing outside the core code needs these. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.513368075@linutronix.de
2021-10-20x86/fpu: Make os_xrstor_booting() privateThomas Gleixner
It's only required in the xstate init code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.455836597@linutronix.de
2021-10-20x86/fpu: Clean up CPU feature testsThomas Gleixner
Further disintegration of internal.h: Move the CPU feature tests to a core header and remove the unused one. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.401510559@linutronix.de
2021-10-20x86/fpu: Move context switch and exit to user inlines into sched.hThomas Gleixner
internal.h is a kitchen sink which needs to get out of the way to prepare for the upcoming changes. Move the context switch and exit to user inlines into a separate header, which is all that code needs. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.349132461@linutronix.de
2021-10-20x86/fpu: Mark fpu__init_prepare_fx_sw_frame() as __initThomas Gleixner
No need to keep it around. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.296435736@linutronix.de
2021-10-20x86/fpu: Rework copy_xstate_to_uabi_buf()Thomas Gleixner
Prepare for replacing the KVM copy xstate to user function by extending copy_xstate_to_uabi_buf() with a pkru argument which allows the caller to hand in the pkru value, which is required for KVM because the guest PKRU is not accessible via current. Fixup all callsites accordingly. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.191902137@linutronix.de
2021-10-20x86/fpu: Replace KVMs home brewed FPU copy from userThomas Gleixner
Copying a user space buffer to the memory buffer is already available in the FPU core. The copy mechanism in KVM lacks sanity checks and needs to use cpuid() to lookup the offset of each component, while the FPU core has this information cached. Make the FPU core variant accessible for KVM and replace the home brewed mechanism. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: kvm@vger.kernel.org Link: https://lkml.kernel.org/r/20211015011539.134065207@linutronix.de
2021-10-20x86/fpu: Move KVMs FPU swapping to FPU coreThomas Gleixner
Swapping the host/guest FPU is directly fiddling with FPU internals which requires 5 exports. The upcoming support of dynamically enabled states would even need more. Implement a swap function in the FPU core code and export that instead. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Cc: kvm@vger.kernel.org Link: https://lkml.kernel.org/r/20211015011539.076072399@linutronix.de
2021-10-20x86/fpu/xstate: Mark all init only functions __initThomas Gleixner
No point to keep them around after boot. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011539.017919252@linutronix.de
2021-10-20x86/fpu/xstate: Provide and use for_each_xfeature()Thomas Gleixner
These loops evaluating xfeature bits are really hard to read. Create an iterator and use for_each_set_bit_from() inside which already does the right thing. No functional changes. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011538.958107505@linutronix.de
2021-10-20x86/fpu: Cleanup xstate xcomp_bv initializationThomas Gleixner
No point in having this duplicated all over the place with needlessly different defines. Provide a proper initialization function which initializes user buffers properly and make KVM use it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011538.897664678@linutronix.de
2021-10-20x86/fpu: Do not inherit FPU context for kernel and IO worker threadsThomas Gleixner
There is no reason why kernel and IO worker threads need a full clone of the parent's FPU state. Both are kernel threads which are not supposed to use FPU. So copying a large state or doing XSAVE() is pointless. Just clean out the minimally required state for those tasks. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011538.839822981@linutronix.de
2021-10-20x86/fpu: Remove pointless memset in fpu_clone()Thomas Gleixner
Zeroing the forked task's FPU registers buffer to avoid leaking init optimized stale data into the clone is a pointless exercise for the case where the current task has TIF_NEED_FPU_LOAD set. In that case, the FPU registers state is copied from current's FPU register buffer which can contain stale init optimized data as well. The alledged information leak is non-existant because this stale init optimized data is used nowhere and cannot leak anywhere. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011538.722854569@linutronix.de
2021-10-20x86/fpu: Cleanup the on_boot_cpu clutterThomas Gleixner
Defensive programming is useful, but this on_boot_cpu debug is really silly. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011538.665080855@linutronix.de
2021-10-20x86/fpu: Restrict xsaves()/xrstors() to independent statesThomas Gleixner
These interfaces are really only valid for features which are independently managed and not part of the task context state for various reasons. Tighten the checks and adjust the misleading comments. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011538.608492174@linutronix.de
2021-10-20x86/fpu: Update stale commentsThomas Gleixner
copy_fpstate_to_sigframe() does not have a slow path anymore. Neither does the !ia32 restore in __fpu_restore_sig(). Update the comments accordingly. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211015011538.493570236@linutronix.de
2021-10-18gup: Turn fault_in_pages_{readable,writeable} into fault_in_{readable,writeable}Andreas Gruenbacher
Turn fault_in_pages_{readable,writeable} into versions that return the number of bytes not faulted in, similar to copy_to_user, instead of returning a non-zero value when any of the requested pages couldn't be faulted in. This supports the existing users that require all pages to be faulted in as well as new users that are happy if any pages can be faulted in. Rename the functions to fault_in_{readable,writeable} to make sure this change doesn't silently break things. Neither of these functions is entirely trivial and it doesn't seem useful to inline them, so move them to mm/gup.c. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2021-10-16Merge branch 'x86/urgent' into x86/fpu, to resolve a conflictIngo Molnar
Resolve the conflict between these commits: x86/fpu: 1193f408cd51 ("x86/fpu/signal: Change return type of __fpu_restore_sig() to boolean") x86/urgent: d298b03506d3 ("x86/fpu: Restore the masking out of reserved MXCSR bits") b2381acd3fd9 ("x86/fpu: Mask out the invalid MXCSR bits properly") Conflicts: arch/x86/kernel/fpu/signal.c Signed-off-by: Ingo Molnar <mingo@kernel.org>
2021-10-16x86/fpu: Mask out the invalid MXCSR bits properlyBorislav Petkov
This is a fix for the fix (yeah, /facepalm). The correct mask to use is not the negation of the MXCSR_MASK but the actual mask which contains the supported bits in the MXCSR register. Reported and debugged by Ville Syrjälä <ville.syrjala@linux.intel.com> Fixes: d298b03506d3 ("x86/fpu: Restore the masking out of reserved MXCSR bits") Signed-off-by: Borislav Petkov <bp@suse.de> Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Tested-by: Ser Olmy <ser.olmy@protonmail.com> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/YWgYIYXLriayyezv@intel.com
2021-10-08x86/fpu: Restore the masking out of reserved MXCSR bitsBorislav Petkov
Ser Olmy reported a boot failure: init[1] bad frame in sigreturn frame:(ptrval) ip:b7c9fbe6 sp:bf933310 orax:ffffffff \ in libc-2.33.so[b7bed000+156000] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b CPU: 0 PID: 1 Comm: init Tainted: G W 5.14.9 #1 Hardware name: Hewlett-Packard HP PC/HP Board, BIOS JD.00.06 12/06/2001 Call Trace: dump_stack_lvl dump_stack panic do_exit.cold do_group_exit get_signal arch_do_signal_or_restart ? force_sig_info_to_task ? force_sig exit_to_user_mode_prepare syscall_exit_to_user_mode do_int80_syscall_32 entry_INT80_32 on an old 32-bit Intel CPU: vendor_id : GenuineIntel cpu family : 6 model : 6 model name : Celeron (Mendocino) stepping : 5 microcode : 0x3 Ser bisected the problem to the commit in Fixes. tglx suggested reverting the rejection of invalid MXCSR values which this commit introduced and replacing it with what the old code did - simply masking them out to zero. Further debugging confirmed his suggestion: fpu->state.fxsave.mxcsr: 0xb7be13b4, mxcsr_feature_mask: 0xffbf WARNING: CPU: 0 PID: 1 at arch/x86/kernel/fpu/signal.c:384 __fpu_restore_sig+0x51f/0x540 so restore the original behavior only for 32-bit kernels where you have ancient machines with buggy hardware. For 32-bit programs on 64-bit kernels, user space which supplies wrong MXCSR values is considered malicious so fail the sigframe restoration there. Fixes: 6f9866a166cd ("x86/fpu/signal: Let xrstor handle the features to init") Reported-by: Ser Olmy <ser.olmy@protonmail.com> Signed-off-by: Borislav Petkov <bp@suse.de> Tested-by: Ser Olmy <ser.olmy@protonmail.com> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/YVtA67jImg3KlBTw@zn.tnic
2021-09-23x86/fpu/signal: Fix missed conversion to correct boolean retval in ↵Anders Roxell
save_xstate_epilog() Fix the missing return code polarity in save_xstate_epilog(). [ bp: Massage, use the right commit in the Fixes: tag ] Fixes: 2af07f3a6e9f ("x86/fpu/signal: Change return type of copy_fpregs_to_sigframe() helpers to boolean") Reported-by: Remi Duraffort <remi.duraffort@linaro.org> Signed-off-by: Anders Roxell <anders.roxell@linaro.org> Signed-off-by: Borislav Petkov <bp@suse.de> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Link: https://github.com/ClangBuiltLinux/linux/issues/1461 Link: https://lkml.kernel.org/r/20210922200901.1823741-1-anders.roxell@linaro.org
2021-09-14x86/fpu/signal: Change return code of restore_fpregs_from_user() to booleanThomas Gleixner
__fpu_sig_restore() only needs information about success or fail and no real error code. This cleans up the confusing conversion of the trap number, which is returned by the *RSTOR() exception fixups, to an error code. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210908132526.084109938@linutronix.de
2021-09-14x86/fpu/signal: Change return code of check_xstate_in_sigframe() to booleanThomas Gleixner
__fpu_sig_restore() only needs success/fail information and no detailed error code. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210908132526.024024598@linutronix.de
2021-09-14x86/fpu/signal: Change return type of __fpu_restore_sig() to booleanThomas Gleixner
Now that fpu__restore_sig() returns a boolean get rid of the individual error codes in __fpu_restore_sig() as well. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210908132525.966197097@linutronix.de
2021-09-14x86/fpu/signal: Change return type of fpu__restore_sig() to booleanThomas Gleixner
None of the call sites cares about the error code. All they need to know is whether the function succeeded or not. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210908132525.909065931@linutronix.de
2021-09-14x86/fpu/signal: Change return type of copy_fpregs_to_sigframe() helpers to ↵Thomas Gleixner
boolean Now that copy_fpregs_to_sigframe() returns boolean the individual return codes in the related helper functions do not make sense anymore. Change them to return boolean success/fail. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210908132525.794334915@linutronix.de
2021-09-14x86/fpu/signal: Change return type of copy_fpstate_to_sigframe() to booleanThomas Gleixner
None of the call sites cares about the actual return code. Change the return type to boolean and return 'true' on success. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210908132525.736773588@linutronix.de
2021-09-14x86/fpu/signal: Move xstate clearing out of copy_fpregs_to_sigframe()Thomas Gleixner
When the direct saving of the FPU registers to the user space sigframe fails, copy_fpregs_to_sigframe() attempts to clear the user buffer. The most likely reason for such a fail is a page fault. As copy_fpregs_to_sigframe() is invoked with pagefaults disabled the chance that __clear_user() succeeds is minuscule. Move the clearing out into the caller which replaces the fault_in_pages_writeable() in that error handling path. The return value confusion will be cleaned up separately. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210908132525.679356300@linutronix.de
2021-09-14x86/fpu/signal: Move header zeroing out of xsave_to_user_sigframe()Thomas Gleixner
There is no reason to have the header zeroing in the pagefault disabled region. Do it upfront once. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210908132525.621674721@linutronix.de
2021-09-13x86/fpu/signal: Clarify exception handling in restore_fpregs_from_user()Thomas Gleixner
FPU restore from a signal frame can trigger various exceptions. The exceptions are caught with an exception table entry. The handler of this entry stores the trap number in EAX. The FPU specific fixup negates that trap number to convert it into an negative error code. Any other exception than #PF is fatal and recovery is not possible. This relies on the fact that the #PF exception number is the same as EFAULT, but that's not really obvious. Remove the negation from the exception fixup as it really has no value and check for X86_TRAP_PF at the call site. There is still confusion due to the return code conversion for the error case which will be cleaned up separately. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210908132525.506192488@linutronix.de
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