kernel.git/arch/x86/kernel, branch linux-4.14.y

x86: Fix .brk attribute in linker script

2023-11-08T10:21:08Z

commit 7e09ac27f43b382f5fe9bb7c7f4c465ece1f8a23 upstream. Commit in Fixes added the "NOLOAD" attribute to the .brk section as a "failsafe" measure. Unfortunately, this leads to the linker no longer covering the .brk section in a program header, resulting in the kernel loader not knowing that the memory for the .brk section must be reserved. This has led to crashes when loading the kernel as PV dom0 under Xen, but other scenarios could be hit by the same problem (e.g. in case an uncompressed kernel is used and the initrd is placed directly behind it). So drop the "NOLOAD" attribute. This has been verified to correctly cover the .brk section by a program header of the resulting ELF file. Fixes: e32683c6f7d2 ("x86/mm: Fix RESERVE_BRK() for older binutils") Signed-off-by: Juergen Gross Signed-off-by: Borislav Petkov Reviewed-by: Josh Poimboeuf Link: https://lore.kernel.org/r/20220630071441.28576-4-jgross@suse.com Signed-off-by: Greg Kroah-Hartman

x86/mm: Fix RESERVE_BRK() for older binutils

2023-11-08T10:21:07Z

commit e32683c6f7d22ba624e0bfc58b02cf3348bdca63 upstream. With binutils 2.26, RESERVE_BRK() causes a build failure: /tmp/ccnGOKZ5.s: Assembler messages: /tmp/ccnGOKZ5.s:98: Error: missing ')' /tmp/ccnGOKZ5.s:98: Error: missing ')' /tmp/ccnGOKZ5.s:98: Error: missing ')' /tmp/ccnGOKZ5.s:98: Error: junk at end of line, first unrecognized character is `U' The problem is this line: RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE) Specifically, the INIT_PGT_BUF_SIZE macro which (via PAGE_SIZE's use _AC()) has a "1UL", which makes older versions of the assembler unhappy. Unfortunately the _AC() macro doesn't work for inline asm. Inline asm was only needed here to convince the toolchain to add the STT_NOBITS flag. However, if a C variable is placed in a section whose name is prefixed with ".bss", GCC and Clang automatically set STT_NOBITS. In fact, ".bss..page_aligned" already relies on this trick. So fix the build failure (and simplify the macro) by allocating the variable in C. Also, add NOLOAD to the ".brk" output section clause in the linker script. This is a failsafe in case the ".bss" prefix magic trick ever stops working somehow. If there's a section type mismatch, the GNU linker will force the ".brk" output section to be STT_NOBITS. The LLVM linker will fail with a "section type mismatch" error. Note this also changes the name of the variable from .brk.##name to __brk_##name. The variable names aren't actually used anywhere, so it's harmless. Fixes: a1e2c031ec39 ("x86/mm: Simplify RESERVE_BRK()") Reported-by: Joe Damato Reported-by: Byungchul Park Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Tested-by: Joe Damato Link: https://lore.kernel.org/r/22d07a44c80d8e8e1e82b9a806ddc8c6bbb2606e.1654759036.git.jpoimboe@kernel.org [nathan: Fix conflict due to lack of 360db4ace311 and resolve silent conflict with 360db4ace3117] Signed-off-by: Nathan Chancellor Signed-off-by: Greg Kroah-Hartman

x86/i8259: Skip probing when ACPI/MADT advertises PCAT compatibility

2023-11-08T10:21:07Z

commit 128b0c9781c9f2651bea163cb85e52a6c7be0f9e upstream. David and a few others reported that on certain newer systems some legacy interrupts fail to work correctly. Debugging revealed that the BIOS of these systems leaves the legacy PIC in uninitialized state which makes the PIC detection fail and the kernel switches to a dummy implementation. Unfortunately this fallback causes quite some code to fail as it depends on checks for the number of legacy PIC interrupts or the availability of the real PIC. In theory there is no reason to use the PIC on any modern system when IO/APIC is available, but the dependencies on the related checks cannot be resolved trivially and on short notice. This needs lots of analysis and rework. The PIC detection has been added to avoid quirky checks and force selection of the dummy implementation all over the place, especially in VM guest scenarios. So it's not an option to revert the relevant commit as that would break a lot of other scenarios. One solution would be to try to initialize the PIC on detection fail and retry the detection, but that puts the burden on everything which does not have a PIC. Fortunately the ACPI/MADT table header has a flag field, which advertises in bit 0 that the system is PCAT compatible, which means it has a legacy 8259 PIC. Evaluate that bit and if set avoid the detection routine and keep the real PIC installed, which then gets initialized (for nothing) and makes the rest of the code with all the dependencies work again. Fixes: e179f6914152 ("x86, irq, pic: Probe for legacy PIC and set legacy_pic appropriately") Reported-by: David Lazar Signed-off-by: Thomas Gleixner Tested-by: David Lazar Reviewed-by: Hans de Goede Reviewed-by: Mario Limonciello Cc: stable@vger.kernel.org Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218003 Link: https://lore.kernel.org/r/875y2u5s8g.ffs@tglx Signed-off-by: Greg Kroah-Hartman

x86/cpu: Fix AMD erratum #1485 on Zen4-based CPUs

2023-10-25T09:13:31Z

commit f454b18e07f518bcd0c05af17a2239138bff52de upstream. Fix erratum #1485 on Zen4 parts where running with STIBP disabled can cause an #UD exception. The performance impact of the fix is negligible. Reported-by: René Rebe Signed-off-by: Borislav Petkov (AMD) Tested-by: René Rebe Cc: Link: https://lore.kernel.org/r/D99589F4-BC5D-430B-87B2-72C20370CF57@exactcode.com Signed-off-by: Greg Kroah-Hartman

x86/APM: drop the duplicate APM_MINOR_DEV macro

2023-09-23T08:46:58Z

[ Upstream commit 4ba2909638a29630a346d6c4907a3105409bee7d ] This source file already includes , which contains the same macro. It doesn't need to be defined here again. Fixes: 874bcd00f520 ("apm-emulation: move APM_MINOR_DEV to include/linux/miscdevice.h") Signed-off-by: Randy Dunlap Cc: Jiri Kosina Cc: x86@kernel.org Cc: Sohil Mehta Cc: Corentin Labbe Reviewed-by: Sohil Mehta Link: https://lore.kernel.org/r/20230728011120.759-1-rdunlap@infradead.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

x86/fpu: Set X86_FEATURE_OSXSAVE feature after enabling OSXSAVE in CR4

2023-08-30T14:35:15Z

commit 2c66ca3949dc701da7f4c9407f2140ae425683a5 upstream. 0-Day found a 34.6% regression in stress-ng's 'af-alg' test case, and bisected it to commit b81fac906a8f ("x86/fpu: Move FPU initialization into arch_cpu_finalize_init()"), which optimizes the FPU init order, and moves the CR4_OSXSAVE enabling into a later place: arch_cpu_finalize_init identify_boot_cpu identify_cpu generic_identify get_cpu_cap --> setup cpu capability ... fpu__init_cpu fpu__init_cpu_xstate cr4_set_bits(X86_CR4_OSXSAVE); As the FPU is not yet initialized the CPU capability setup fails to set X86_FEATURE_OSXSAVE. Many security module like 'camellia_aesni_avx_x86_64' depend on this feature and therefore fail to load, causing the regression. Cure this by setting X86_FEATURE_OSXSAVE feature right after OSXSAVE enabling. [ tglx: Moved it into the actual BSP FPU initialization code and added a comment ] Fixes: b81fac906a8f ("x86/fpu: Move FPU initialization into arch_cpu_finalize_init()") Reported-by: kernel test robot Signed-off-by: Feng Tang Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/lkml/202307192135.203ac24e-oliver.sang@intel.com Link: https://lore.kernel.org/lkml/20230823065747.92257-1-feng.tang@intel.com Signed-off-by: Greg Kroah-Hartman

treewide: Remove uninitialized_var() usage

2023-08-11T09:33:32Z

commit 3f649ab728cda8038259d8f14492fe400fbab911 upstream. Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var$([^$]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe # IB Acked-by: Kalle Valo # wireless drivers Reviewed-by: Chao Yu # erofs Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman

x86/smp: Use dedicated cache-line for mwait_play_dead()

2023-08-11T09:33:32Z

commit f9c9987bf52f4e42e940ae217333ebb5a4c3b506 upstream. Monitoring idletask::thread_info::flags in mwait_play_dead() has been an obvious choice as all what is needed is a cache line which is not written by other CPUs. But there is a use case where a "dead" CPU needs to be brought out of MWAIT: kexec(). This is required as kexec() can overwrite text, pagetables, stacks and the monitored cacheline of the original kernel. The latter causes MWAIT to resume execution which obviously causes havoc on the kexec kernel which results usually in triple faults. Use a dedicated per CPU storage to prepare for that. Signed-off-by: Thomas Gleixner Reviewed-by: Ashok Raj Reviewed-by: Borislav Petkov (AMD) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230615193330.434553750@linutronix.de Signed-off-by: Greg Kroah-Hartman

x86/microcode/AMD: Load late on both threads too

2023-08-11T09:33:31Z

commit a32b0f0db3f396f1c9be2fe621e77c09ec3d8e7d upstream. Do the same as early loading - load on both threads. Signed-off-by: Borislav Petkov (AMD) Cc: Link: https://lore.kernel.org/r/20230605141332.25948-1-bp@alien8.de Signed-off-by: Greg Kroah-Hartman

x86: fix backwards merge of GDS/SRSO bit

2023-08-08T17:48:25Z

Stable-tree-only change. Due to the way the GDS and SRSO patches flowed into the stable tree, it was a 50% chance that the merge of the which value GDS and SRSO should be. Of course, I lost that bet, and chose the opposite of what Linus chose in commit 64094e7e3118 ("Merge tag 'gds-for-linus-2023-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip") Fix this up by switching the values to match what is now in Linus's tree as that is the correct value to mirror. Signed-off-by: Greg Kroah-Hartman