kernel.git/arch/x86/include/asm/fpu, branch linux-4.19.y

x86/fpu: Remove cpuinfo argument from init functions

2023-08-08T17:49:18Z

commit 1f34bb2a24643e0087652d81078e4f616562738d upstream Nothing in the call chain requires it Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230613224545.783704297@linutronix.de Signed-off-by: Daniel Sneddon Signed-off-by: Greg Kroah-Hartman

x86/fpu: Make init_fpstate correct with optimized XSAVE

2021-08-26T12:36:42Z

commit f9dfb5e390fab2df9f7944bb91e7705aba14cd26 upstream. The XSAVE init code initializes all enabled and supported components with XRSTOR(S) to init state. Then it XSAVEs the state of the components back into init_fpstate which is used in several places to fill in the init state of components. This works correctly with XSAVE, but not with XSAVEOPT and XSAVES because those use the init optimization and skip writing state of components which are in init state. So init_fpstate.xsave still contains all zeroes after this operation. There are two ways to solve that: 1) Use XSAVE unconditionally, but that requires to reshuffle the buffer when XSAVES is enabled because XSAVES uses compacted format. 2) Save the components which are known to have a non-zero init state by other means. Looking deeper, #2 is the right thing to do because all components the kernel supports have all-zeroes init state except the legacy features (FP, SSE). Those cannot be hard coded because the states are not identical on all CPUs, but they can be saved with FXSAVE which avoids all conditionals. Use FXSAVE to save the legacy FP/SSE components in init_fpstate along with a BUILD_BUG_ON() which reminds developers to validate that a newly added component has all zeroes init state. As a bonus remove the now unused copy_xregs_to_kernel_booting() crutch. The XSAVE and reshuffle method can still be implemented in the unlikely case that components are added which have a non-zero init state and no other means to save them. For now, FXSAVE is just simple and good enough. [ bp: Fix a typo or two in the text. ] Fixes: 6bad06b76892 ("x86, xsave: Use xsaveopt in context-switch path when supported") Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Reviewed-by: Borislav Petkov Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20210618143444.587311343@linutronix.de Signed-off-by: Greg Kroah-Hartman

x86/fpu: Return proper error codes from user access functions

2021-07-20T14:16:11Z

[ Upstream commit aee8c67a4faa40a8df4e79316dbfc92d123989c1 ] When *RSTOR from user memory raises an exception, there is no way to differentiate them. That's bad because it forces the slow path even when the failure was not a fault. If the operation raised eg. #GP then going through the slow path is pointless. Use _ASM_EXTABLE_FAULT() which stores the trap number and let the exception fixup return the negated trap number as error. This allows to separate the fast path and let it handle faults directly and avoid the slow path for all other exceptions. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20210623121457.601480369@linutronix.de Signed-off-by: Sasha Levin

x86/fpu: Don't export __kernel_fpu_{begin,end}()

2019-05-02T07:58:59Z

commit 12209993e98c5fa1855c467f22a24e3d5b8be205 upstream. There is one user of __kernel_fpu_begin() and before invoking it, it invokes preempt_disable(). So it could invoke kernel_fpu_begin() right away. The 32bit version of arch_efi_call_virt_setup() and arch_efi_call_virt_teardown() does this already. The comment above *kernel_fpu*() claims that before invoking __kernel_fpu_begin() preemption should be disabled and that KVM is a good example of doing it. Well, KVM doesn't do that since commit f775b13eedee2 ("x86,kvm: move qemu/guest FPU switching out to vcpu_run") so it is not an example anymore. With EFI gone as the last user of __kernel_fpu_{begin|end}(), both can be made static and not exported anymore. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Borislav Petkov Reviewed-by: Rik van Riel Cc: "H. Peter Anvin" Cc: "Jason A. Donenfeld" Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Dave Hansen Cc: Ingo Molnar Cc: Nicolai Stange Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Thomas Gleixner Cc: kvm ML Cc: linux-efi Cc: x86-ml Link: https://lkml.kernel.org/r/20181129150210.2k4mawt37ow6c2vq@linutronix.de Signed-off-by: Greg Kroah-Hartman

x86/fpu: Add might_fault() to user_insn()

2019-02-12T18:47:04Z

[ Upstream commit 6637401c35b2f327a35d27f44bda05e327f2f017 ] Every user of user_insn() passes an user memory pointer to this macro. Add might_fault() to user_insn() so we can spot users which are using this macro in sections where page faulting is not allowed. [ bp: Space it out to make it more visible. ] Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Borislav Petkov Reviewed-by: Rik van Riel Cc: "H. Peter Anvin" Cc: "Jason A. Donenfeld" Cc: Andy Lutomirski Cc: Dave Hansen Cc: Ingo Molnar Cc: Jann Horn Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Thomas Gleixner Cc: kvm ML Cc: x86-ml Link: https://lkml.kernel.org/r/20181128222035.2996-6-bigeasy@linutronix.de Signed-off-by: Sasha Levin

x86/fpu: Fix i486 + no387 boot crash by only saving FPU registers on context switch if there is an FPU

2018-10-17T10:30:38Z

Booting an i486 with "no387 nofxsr" ends with with the following crash: math_emulate: 0060:c101987d Kernel panic - not syncing: Math emulation needed in kernel on the first context switch in user land. The reason is that copy_fpregs_to_fpstate() tries FNSAVE which does not work as the FPU is turned off. This bug was introduced in: f1c8cd0176078 ("x86/fpu: Change fpu->fpregs_active users to fpu->fpstate_active") Add a check for X86_FEATURE_FPU before trying to save FPU registers (we have such a check in switch_fpu_finish() already). Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: stable@vger.kernel.org Fixes: f1c8cd0176078 ("x86/fpu: Change fpu->fpregs_active users to fpu->fpstate_active") Link: http://lkml.kernel.org/r/20181016202525.29437-4-bigeasy@linutronix.de Signed-off-by: Ingo Molnar

signal: Unify and correct copy_siginfo_to_user32

2018-01-16T01:56:20Z

Among the existing architecture specific versions of copy_siginfo_to_user32 there are several different implementation problems. Some architectures fail to handle all of the cases in in the siginfo union. Some architectures perform a blind copy of the siginfo union when the si_code is negative. A blind copy suggests the data is expected to be in 32bit siginfo format, which means that receiving such a signal via signalfd won't work, or that the data is in 64bit siginfo and the code is copying nonsense to userspace. Create a single instance of copy_siginfo_to_user32 that all of the architectures can share, and teach it to handle all of the cases in the siginfo union correctly, with the assumption that siginfo is stored internally to the kernel is 64bit siginfo format. A special case is made for x86 x32 format. This is needed as presence of both x32 and ia32 on x86_64 results in two different 32bit signal formats. By allowing this small special case there winds up being exactly one code base that needs to be maintained between all of the architectures. Vastly increasing the testing base and the chances of finding bugs. As the x86 copy of copy_siginfo_to_user32 the call of the x86 signal_compat_build_tests were moved into sigaction_compat_abi, so that they will keep running. Signed-off-by: "Eric W. Biederman"

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02T10:10:55Z

Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart Reviewed-by: Philippe Ombredanne Reviewed-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

x86/fpu: Introduce validate_xstate_header()

2017-09-26T07:43:45Z

Move validation of user-supplied xstate_header into a helper function, in preparation of calling it from both the ptrace and sigreturn syscall paths. The new function also considers it to be an error if *any* reserved bits are set, whereas before we were just clearing most of them silently. This should reduce the chance of bugs that fail to correctly validate user-supplied XSAVE areas. It also will expose any broken userspace programs that set the other reserved bits; this is desirable because such programs will lose compatibility with future CPUs and kernels if those bits are ever used for anything. (There shouldn't be any such programs, and in fact in the case where the compacted format is in use we were already validating xfeatures. But you never know...) Signed-off-by: Eric Biggers Cc: Andrew Morton Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: Dmitry Vyukov Cc: Eric Biggers Cc: Fenghua Yu Cc: Kees Cook Cc: Kevin Hao Cc: Linus Torvalds Cc: Michael Halcrow Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Cc: Wanpeng Li Cc: Yu-cheng Yu Cc: kernel-hardening@lists.openwall.com Link: http://lkml.kernel.org/r/20170924105913.9157-2-mingo@kernel.org Signed-off-by: Ingo Molnar

x86/fpu: Rename fpu__activate_fpstate_read/write() to fpu__prepare_[read|write]()

2017-09-26T07:43:44Z

As per the new nomenclature we don't 'activate' the FPU state anymore, we initialize it. So drop the _activate_fpstate name from these functions, which were a bit of a mouthful anyway, and name them: fpu__prepare_read() fpu__prepare_write() Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Eric Biggers Cc: Fenghua Yu Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar