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2020-08-04Merge tag 'x86-fsgsbase-2020-08-04' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fsgsbase from Thomas Gleixner: "Support for FSGSBASE. Almost 5 years after the first RFC to support it, this has been brought into a shape which is maintainable and actually works. This final version was done by Sasha Levin who took it up after Intel dropped the ball. Sasha discovered that the SGX (sic!) offerings out there ship rogue kernel modules enabling FSGSBASE behind the kernels back which opens an instantanious unpriviledged root hole. The FSGSBASE instructions provide a considerable speedup of the context switch path and enable user space to write GSBASE without kernel interaction. This enablement requires careful handling of the exception entries which go through the paranoid entry path as they can no longer rely on the assumption that user GSBASE is positive (as enforced via prctl() on non FSGSBASE enabled systemn). All other entries (syscalls, interrupts and exceptions) can still just utilize SWAPGS unconditionally when the entry comes from user space. Converting these entries to use FSGSBASE has no benefit as SWAPGS is only marginally slower than WRGSBASE and locating and retrieving the kernel GSBASE value is not a free operation either. The real benefit of RD/WRGSBASE is the avoidance of the MSR reads and writes. The changes come with appropriate selftests and have held up in field testing against the (sanitized) Graphene-SGX driver" * tag 'x86-fsgsbase-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits) x86/fsgsbase: Fix Xen PV support x86/ptrace: Fix 32-bit PTRACE_SETREGS vs fsbase and gsbase selftests/x86/fsgsbase: Add a missing memory constraint selftests/x86/fsgsbase: Fix a comment in the ptrace_write_gsbase test selftests/x86: Add a syscall_arg_fault_64 test for negative GSBASE selftests/x86/fsgsbase: Test ptracer-induced GS base write with FSGSBASE selftests/x86/fsgsbase: Test GS selector on ptracer-induced GS base write Documentation/x86/64: Add documentation for GS/FS addressing mode x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2 x86/cpu: Enable FSGSBASE on 64bit by default and add a chicken bit x86/entry/64: Handle FSGSBASE enabled paranoid entry/exit x86/entry/64: Introduce the FIND_PERCPU_BASE macro x86/entry/64: Switch CR3 before SWAPGS in paranoid entry x86/speculation/swapgs: Check FSGSBASE in enabling SWAPGS mitigation x86/process/64: Use FSGSBASE instructions on thread copy and ptrace x86/process/64: Use FSBSBASE in switch_to() if available x86/process/64: Make save_fsgs_for_kvm() ready for FSGSBASE x86/fsgsbase/64: Enable FSGSBASE instructions in helper functions x86/fsgsbase/64: Add intrinsics for FSGSBASE instructions x86/cpu: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE ...
2020-08-04Merge tag 'x86-entry-2020-08-04' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 conversion to generic entry code from Thomas Gleixner: "The conversion of X86 syscall, interrupt and exception entry/exit handling to the generic code. Pretty much a straight-forward 1:1 conversion plus the consolidation of the KVM handling of pending work before entering guest mode" * tag 'x86-entry-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/kvm: Use __xfer_to_guest_mode_work_pending() in kvm_run_vcpu() x86/kvm: Use generic xfer to guest work function x86/entry: Cleanup idtentry_enter/exit x86/entry: Use generic interrupt entry/exit code x86/entry: Cleanup idtentry_entry/exit_user x86/entry: Use generic syscall exit functionality x86/entry: Use generic syscall entry function x86/ptrace: Provide pt_regs helper for entry/exit x86/entry: Move user return notifier out of loop x86/entry: Consolidate 32/64 bit syscall entry x86/entry: Consolidate check_user_regs() x86: Correct noinstr qualifiers x86/idtentry: Remove stale comment
2020-07-24x86/entry: Use generic syscall exit functionalityThomas Gleixner
Replace the x86 variant with the generic version. Provide the relevant architecture specific helper functions and defines. Use a temporary define for idtentry_exit_user which will be cleaned up seperately. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/20200722220520.494648601@linutronix.de
2020-07-21exec: Implement kernel_execveEric W. Biederman
To allow the kernel not to play games with set_fs to call exec implement kernel_execve. The function kernel_execve takes pointers into kernel memory and copies the values pointed to onto the new userspace stack. The calls with arguments from kernel space of do_execve are replaced with calls to kernel_execve. The calls do_execve and do_execveat are made static as there are now no callers outside of exec. The comments that mention do_execve are updated to refer to kernel_execve or execve depending on the circumstances. In addition to correcting the comments, this makes it easy to grep for do_execve and verify it is not used. Inspired-by: https://lkml.kernel.org/r/20200627072704.2447163-1-hch@lst.de Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/87wo365ikj.fsf@x220.int.ebiederm.org Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2020-06-18x86/entry/64: Handle FSGSBASE enabled paranoid entry/exitChang S. Bae
Without FSGSBASE, user space cannot change GSBASE other than through a PRCTL. The kernel enforces that the user space GSBASE value is postive as negative values are used for detecting the kernel space GSBASE value in the paranoid entry code. If FSGSBASE is enabled, user space can set arbitrary GSBASE values without kernel intervention, including negative ones, which breaks the paranoid entry assumptions. To avoid this, paranoid entry needs to unconditionally save the current GSBASE value independent of the interrupted context, retrieve and write the kernel GSBASE and unconditionally restore the saved value on exit. The restore happens either in paranoid_exit or in the special exit path of the NMI low level code. All other entry code pathes which use unconditional SWAPGS are not affected as they do not depend on the actual content. [ tglx: Massaged changelogs and comments ] Suggested-by: H. Peter Anvin <hpa@zytor.com> Suggested-by: Andy Lutomirski <luto@kernel.org> Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/1557309753-24073-13-git-send-email-chang.seok.bae@intel.com Link: https://lkml.kernel.org/r/20200528201402.1708239-12-sashal@kernel.org
2020-06-18x86/entry/64: Switch CR3 before SWAPGS in paranoid entryChang S. Bae
When FSGSBASE is enabled, the GSBASE handling in paranoid entry will need to retrieve the kernel GSBASE which requires that the kernel page table is active. As the CR3 switch to the kernel page tables (PTI is active) does not depend on kernel GSBASE, move the CR3 switch in front of the GSBASE handling. Comment the EBX content while at it. No functional change. [ tglx: Rewrote changelog and comments ] Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/1557309753-24073-11-git-send-email-chang.seok.bae@intel.com Link: https://lkml.kernel.org/r/20200528201402.1708239-10-sashal@kernel.org
2020-06-11x86/entry: Unbreak __irqentry_text_start/end magicThomas Gleixner
The entry rework moved interrupt entry code from the irqentry to the noinstr section which made the irqentry section empty. This breaks boundary checks which rely on the __irqentry_text_start/end markers to find out whether a function in a stack trace is interrupt/exception entry code. This affects the function graph tracer and filter_irq_stacks(). As the IDT entry points are all sequentialy emitted this is rather simple to unbreak by injecting __irqentry_text_start/end as global labels. To make this work correctly: - Remove the IRQENTRY_TEXT section from the x86 linker script - Define __irqentry so it breaks the build if it's used - Adjust the entry mirroring in PTI - Remove the redundant kprobes and unwinder bound checks Reported-by: Qian Cai <cai@lca.pw> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2020-06-11x86/entry: Remove DBn stacksPeter Zijlstra
Both #DB itself, as all other IST users (NMI, #MC) now clear DR7 on entry. Combined with not allowing breakpoints on entry/noinstr/NOKPROBE text and no single step (EFLAGS.TF) inside the #DB handler should guarantee no nested #DB. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20200529213321.303027161@infradead.org
2020-06-11x86/entry: Remove the TRACE_IRQS cruftThomas Gleixner
No more users. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202120.523289762@linutronix.de
2020-06-11x86/entry: Move paranoid irq tracing out of ASM codeThomas Gleixner
The last step to remove the irq tracing cruft from ASM. Ignore #DF as the maschine is going to die anyway. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202120.414043330@linutronix.de
2020-06-11x86/entry/64: Remove TRACE_IRQS_*_DEBUGThomas Gleixner
Since INT3/#BP no longer runs on an IST, this workaround is no longer required. Tested by running lockdep+ftrace as described in the initial commit: 5963e317b1e9 ("ftrace/x86: Do not change stacks in DEBUG when calling lockdep") Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202120.319418546@linutronix.de
2020-06-11x86/entry/64: Remove IRQ stack switching ASMThomas Gleixner
No more users. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202120.021462159@linutronix.de
2020-06-11x86/entry: Remove the apic/BUILD interrupt leftoversThomas Gleixner
Remove all the code which was there to emit the system vector stubs. All users are gone. Move the now unused GET_CR2_INTO macro muck to head_64.S where the last user is. Fixup the eye hurting comment there while at it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202119.927433002@linutronix.de
2020-06-11x86/entry: Convert reschedule interrupt to IDTENTRY_SYSVEC_SIMPLEThomas Gleixner
The scheduler IPI does not need the full interrupt entry handling logic when the entry is from kernel mode. Use IDTENTRY_SYSVEC_SIMPLE and spare all the overhead. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202119.835425642@linutronix.de
2020-06-11x86/entry: Convert XEN hypercall vector to IDTENTRY_SYSVECThomas Gleixner
Convert the last oldstyle defined vector to IDTENTRY_SYSVEC: - Implement the C entry point with DEFINE_IDTENTRY_SYSVEC - Emit the ASM stub with DECLARE_IDTENTRY_SYSVEC - Remove the ASM idtentries in 64-bit - Remove the BUILD_INTERRUPT entries in 32-bit - Remove the old prototypes Fixup the related XEN code by providing the primary C entry point in x86 to avoid cluttering the generic code with X86'isms. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202119.741950104@linutronix.de
2020-06-11x86/entry: Convert various hypervisor vectors to IDTENTRY_SYSVECThomas Gleixner
Convert various hypervisor vectors to IDTENTRY_SYSVEC: - Implement the C entry point with DEFINE_IDTENTRY_SYSVEC - Emit the ASM stub with DECLARE_IDTENTRY_SYSVEC - Remove the ASM idtentries in 64-bit - Remove the BUILD_INTERRUPT entries in 32-bit - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Wei Liu <wei.liu@kernel.org> Link: https://lore.kernel.org/r/20200521202119.647997594@linutronix.de
2020-06-11x86/entry: Convert KVM vectors to IDTENTRY_SYSVEC*Thomas Gleixner
Convert KVM specific system vectors to IDTENTRY_SYSVEC*: The two empty stub handlers which only increment the stats counter do no need to run on the interrupt stack. Use IDTENTRY_SYSVEC_SIMPLE for them. The wakeup handler does more work and runs on the interrupt stack. None of these handlers need to save and restore the irq_regs pointer. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202119.555715519@linutronix.de
2020-06-11x86/entry: Convert various system vectorsThomas Gleixner
Convert various system vectors to IDTENTRY_SYSVEC: - Implement the C entry point with DEFINE_IDTENTRY_SYSVEC - Emit the ASM stub with DECLARE_IDTENTRY_SYSVEC - Remove the ASM idtentries in 64-bit - Remove the BUILD_INTERRUPT entries in 32-bit - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202119.464812973@linutronix.de
2020-06-11x86/entry: Convert SMP system vectors to IDTENTRY_SYSVECThomas Gleixner
Convert SMP system vectors to IDTENTRY_SYSVEC: - Implement the C entry point with DEFINE_IDTENTRY_SYSVEC - Emit the ASM stub with DECLARE_IDTENTRY_SYSVEC - Remove the ASM idtentries in 64-bit - Remove the BUILD_INTERRUPT entries in 32-bit - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202119.372234635@linutronix.de
2020-06-11x86/entry: Convert APIC interrupts to IDTENTRY_SYSVECThomas Gleixner
Convert APIC interrupts to IDTENTRY_SYSVEC: - Implement the C entry point with DEFINE_IDTENTRY_SYSVEC - Emit the ASM stub with DECLARE_IDTENTRY_SYSVEC - Remove the ASM idtentries in 64-bit - Remove the BUILD_INTERRUPT entries in 32-bit - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202119.280728850@linutronix.de
2020-06-11x86/entry: Provide IDTENTRY_SYSVECThomas Gleixner
Provide IDTENTRY variants for system vectors to consolidate the different mechanisms to emit the ASM stubs for 32- and 64-bit. On 64-bit this also moves the stack switching from ASM to C code. 32-bit will excute the system vectors w/o stack switching as before. The simple variant is meant for "empty" system vectors like scheduler IPI and KVM posted interrupt vectors. These do not need the full glory of irq enter/exit handling with softirq processing and more. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202119.185317067@linutronix.de
2020-06-11x86/entry: Use idtentry for interruptsThomas Gleixner
Replace the extra interrupt handling code and reuse the existing idtentry machinery. This moves the irq stack switching on 64-bit from ASM to C code; 32-bit already does the stack switching in C. This requires to remove HAVE_IRQ_EXIT_ON_IRQ_STACK as the stack switch is not longer in the low level entry code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202119.078690991@linutronix.de
2020-06-11x86/entry: Add IRQENTRY_IRQ macroThomas Gleixner
Provide a seperate IDTENTRY macro for device interrupts. Similar to IDTENTRY_ERRORCODE with the addition of invoking irq_enter/exit_rcu() and providing the errorcode as a 'u8' argument to the C function, which truncates the sign extended vector number. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202118.984573165@linutronix.de
2020-06-11x86/irq: Convey vector as argument and not in ptregsThomas Gleixner
Device interrupts which go through do_IRQ() or the spurious interrupt handler have their separate entry code on 64 bit for no good reason. Both 32 and 64 bit transport the vector number through ORIG_[RE]AX in pt_regs. Further the vector number is forced to fit into an u8 and is complemented and offset by 0x80 so it's in the signed character range. Otherwise GAS would expand the pushq to a 5 byte instruction for any vector > 0x7F. Treat the vector number like an error code and hand it to the C function as argument. This allows to get rid of the extra entry code in a later step. Simplify the error code push magic by implementing the pushq imm8 via a '.byte 0x6a, vector' sequence so GAS is not able to screw it up. As the pushq imm8 is sign extending the resulting error code needs to be truncated to 8 bits in C code. Originally-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202118.796915981@linutronix.de
2020-06-11x86/entry/64: Remove error_exit()Thomas Gleixner
No more users. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202118.516757524@linutronix.de
2020-06-11x86/entry: Change exit path of xen_failsafe_callbackThomas Gleixner
xen_failsafe_callback() is invoked from XEN for two cases: 1. Fault while reloading DS, ES, FS or GS 2. Fault while executing IRET #1 retries the IRET after XEN has fixed up the segments. #2 injects a #GP which kills the task For #1 there is no reason to go through the full exception return path because the tasks TIF state is still the same. So just going straight to the IRET path is good enough. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202118.423224507@linutronix.de
2020-06-11x86/entry: Remove the transition leftoversThomas Gleixner
Now that all exceptions are converted over the sane flag is not longer needed. Also the vector argument of idtentry_body on 64-bit is pointless now. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202118.331115895@linutronix.de
2020-06-11x86/entry: Switch page fault exception to IDTENTRY_RAWThomas Gleixner
Convert page fault exceptions to IDTENTRY_RAW: - Implement the C entry point with DEFINE_IDTENTRY_RAW - Add the CR2 read into the exception handler - Add the idtentry_enter/exit_cond_rcu() invocations in in the regular page fault handler and in the async PF part. - Emit the ASM stub with DECLARE_IDTENTRY_RAW - Remove the ASM idtentry in 64-bit - Remove the CR2 read from 64-bit - Remove the open coded ASM entry code in 32-bit - Fix up the XEN/PV code - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202118.238455120@linutronix.de
2020-06-11x86/entry/64: Simplify idtentry_bodyThomas Gleixner
All C functions which do not have an error code have been converted to the new IDTENTRY interface which does not expect an error code in the arguments. Spare the XORL. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202118.145811853@linutronix.de
2020-06-11x86/entry: Switch XEN/PV hypercall entry to IDTENTRYThomas Gleixner
Convert the XEN/PV hypercall to IDTENTRY: - Emit the ASM stub with DECLARE_IDTENTRY - Remove the ASM idtentry in 64-bit - Remove the open coded ASM entry code in 32-bit - Remove the old prototypes The handler stubs need to stay in ASM code as they need corner case handling and adjustment of the stack pointer. Provide a new C function which invokes the entry/exit handling and calls into the XEN handler on the interrupt stack if required. The exit code is slightly different from the regular idtentry_exit() on non-preemptible kernels. If the hypercall is preemptible and need_resched() is set then XEN provides a preempt hypercall scheduling function. Move this functionality into the entry code so it can use the existing idtentry functionality. [ mingo: Build fixes. ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Acked-by: Juergen Gross <jgross@suse.com> Tested-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20200521202118.055270078@linutronix.de
2020-06-11x86/entry/64: Move do_softirq_own_stack() to CThomas Gleixner
The first step to get rid of the ENTER/LEAVE_IRQ_STACK ASM macro maze. Use the new C code helpers to move do_softirq_own_stack() out of ASM code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202117.870911120@linutronix.de
2020-06-11x86/entry: Provide helpers for executing on the irqstackThomas Gleixner
Device interrupt handlers and system vector handlers are executed on the interrupt stack. The stack switch happens in the low level assembly entry code. This conflicts with the efforts to consolidate the exit code in C to ensure correctness vs. RCU and tracing. As there is no way to move #DB away from IST due to the MOV SS issue, the requirements vs. #DB and NMI for switching to the interrupt stack do not exist anymore. The only requirement is that interrupts are disabled. That allows the moving of the stack switching to C code, which simplifies the entry/exit handling further, because it allows the switching of stacks after handling the entry and on exit before handling RCU, returning to usermode and kernel preemption in the same way as for regular exceptions. The initial attempt of having the stack switching in inline ASM caused too much headache vs. objtool and the unwinder. After analysing the use cases it was agreed on that having the stack switch in ASM for the price of an indirect call is acceptable, as the main users are indirect call heavy anyway and the few system vectors which are empty shells (scheduler IPI and KVM posted interrupt vectors) can run from the regular stack. Provide helper functions to check whether the interrupt stack is already active and whether stack switching is required. 64-bit only for now, as 32-bit has a variant of that already. Once this is cleaned up, the two implementations might be consolidated as an additional cleanup on top. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20200521202117.763775313@linutronix.de
2020-06-11x86/entry: Convert double fault exception to IDTENTRY_DFThomas Gleixner
Convert #DF to IDTENTRY_DF - Implement the C entry point with DEFINE_IDTENTRY_DF - Emit the ASM stub with DECLARE_IDTENTRY_DF on 64bit - Remove the ASM idtentry in 64bit - Adjust the 32bit shim code - Fixup the XEN/PV code - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505135315.583415264@linutronix.de
2020-06-11x86/entry: Implement user mode C entry points for #DB and #MCEThomas Gleixner
The MCE entry point uses the same mechanism as the IST entry point for now. For #DB split the inner workings and just keep the nmi_enter/exit() magic in the IST variant. Fixup the ASM code to emit the proper noist_##cfunc call. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505135315.177564104@linutronix.de
2020-06-11x86/entry/64: Remove error code clearing from #DB and #MCE ASM stubThomas Gleixner
The C entry points do not expect an error code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505135314.992621707@linutronix.de
2020-06-11x86/entry: Convert Debug exception to IDTENTRY_DBThomas Gleixner
Convert #DB to IDTENTRY_ERRORCODE: - Implement the C entry point with DEFINE_IDTENTRY_DB - Emit the ASM stub with DECLARE_IDTENTRY - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505135314.900297476@linutronix.de
2020-06-11x86/entry: Convert NMI to IDTENTRY_NMIThomas Gleixner
Convert #NMI to IDTENTRY_NMI: - Implement the C entry point with DEFINE_IDTENTRY_NMI - Fixup the XEN/PV code - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505135314.609932306@linutronix.de
2020-06-11x86/entry: Convert Machine Check to IDTENTRY_ISTThomas Gleixner
Convert #MC to IDTENTRY_MCE: - Implement the C entry points with DEFINE_IDTENTRY_MCE - Emit the ASM stub with DECLARE_IDTENTRY_MCE - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes - Remove the error code from *machine_check_vector() as it is always 0 and not used by any of the functions it can point to. Fixup all the functions as well. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505135314.334980426@linutronix.de
2020-06-11x86/entry: Convert INT3 exception to IDTENTRY_RAWThomas Gleixner
Convert #BP to IDTENTRY_RAW: - Implement the C entry point with DEFINE_IDTENTRY_RAW - Invoke idtentry_enter/exit() from the function body - Emit the ASM stub with DECLARE_IDTENTRY_RAW - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes No functional change. This could be a plain IDTENTRY, but as Peter pointed out INT3 is broken vs. the static key in the context tracking code as this static key might be in the state of being patched and has an int3 which would recurse forever. IDTENTRY_RAW is therefore chosen to allow addressing this issue without lots of code churn. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505135313.938474960@linutronix.de
2020-06-11x86/entry: Convert SIMD coprocessor error exception to IDTENTRYThomas Gleixner
Convert #XF to IDTENTRY_ERRORCODE: - Implement the C entry point with DEFINE_IDTENTRY - Emit the ASM stub with DECLARE_IDTENTRY - Handle INVD_BUG in C - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes - Remove the RCU warning as the new entry macro ensures correctness No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505134906.021552202@linutronix.de
2020-06-11x86/entry: Convert Alignment check exception to IDTENTRYThomas Gleixner
Convert #AC to IDTENTRY_ERRORCODE: - Implement the C entry point with DEFINE_IDTENTRY - Emit the ASM stub with DECLARE_IDTENTRY - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes - Remove the RCU warning as the new entry macro ensures correctness No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505134905.928967113@linutronix.de
2020-06-11x86/entry: Convert Coprocessor error exception to IDTENTRYThomas Gleixner
Convert #MF to IDTENTRY_ERRORCODE: - Implement the C entry point with DEFINE_IDTENTRY - Emit the ASM stub with DECLARE_IDTENTRY - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes - Remove the RCU warning as the new entry macro ensures correctness No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505134905.838823510@linutronix.de
2020-06-11x86/entry: Convert Spurious interrupt bug exception to IDTENTRYThomas Gleixner
Convert #SPURIOUS to IDTENTRY_ERRORCODE: - Implement the C entry point with DEFINE_IDTENTRY - Emit the ASM stub with DECLARE_IDTENTRY - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505134905.728077036@linutronix.de
2020-06-11x86/entry: Convert General protection exception to IDTENTRYThomas Gleixner
Convert #GP to IDTENTRY_ERRORCODE: - Implement the C entry point with DEFINE_IDTENTRY - Emit the ASM stub with DECLARE_IDTENTRY - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes - Remove the RCU warning as the new entry macro ensures correctness No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505134905.637269946@linutronix.de
2020-06-11x86/entry: Convert Stack segment exception to IDTENTRYThomas Gleixner
Convert #SS to IDTENTRY_ERRORCODE: - Implement the C entry point with DEFINE_IDTENTRY - Emit the ASM stub with DECLARE_IDTENTRY - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505134905.539867572@linutronix.de
2020-06-11x86/entry: Convert Segment not present exception to IDTENTRYThomas Gleixner
Convert #NP to IDTENTRY_ERRORCODE: - Implement the C entry point with DEFINE_IDTENTRY - Emit the ASM stub with DECLARE_IDTENTRY - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Andy Lutomirski <luto@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200505134905.443591450@linutronix.de
2020-06-11x86/entry: Convert Invalid TSS exception to IDTENTRYThomas Gleixner
Convert #TS to IDTENTRY_ERRORCODE: - Implement the C entry point with DEFINE_IDTENTRY - Emit the ASM stub with DECLARE_IDTENTRY - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Andy Lutomirski <luto@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200505134905.350676449@linutronix.de
2020-06-11x86/entry: Convert Coprocessor segment overrun exception to IDTENTRYThomas Gleixner
Convert #OLD_MF to IDTENTRY: - Implement the C entry point with DEFINE_IDTENTRY - Emit the ASM stub with DECLARE_IDTENTRY - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Andy Lutomirski <luto@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200505134905.838823510@linutronix.de
2020-06-11x86/entry: Convert Device not available exception to IDTENTRYThomas Gleixner
Convert #NM to IDTENTRY: - Implement the C entry point with DEFINE_IDTENTRY - Emit the ASM stub with DECLARE_IDTENTRY - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Remove the old prototypes - Remove the RCU warning as the new entry macro ensures correctness No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Andy Lutomirski <luto@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200505134905.056243863@linutronix.de
2020-06-11x86/entry: Convert Invalid Opcode exception to IDTENTRYThomas Gleixner
Convert #UD to IDTENTRY: - Implement the C entry point with DEFINE_IDTENTRY - Emit the ASM stub with DECLARE_IDTENTRY - Remove the ASM idtentry in 64bit - Remove the open coded ASM entry code in 32bit - Fixup the XEN/PV code - Fixup the FOOF bug call in fault.c - Remove the old prototypes No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Andy Lutomirski <luto@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200505134904.955511913@linutronix.de