From: Thomas Gleixner <tglx@linutronix.de>
To: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@amacapital.net>,
"H . Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 13/43] x86/entry/64: Use a percpu trampoline stack for IDT entries
Date: Fri, 24 Nov 2017 12:27:03 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.20.1711241024560.1757@nanos> (raw)
In-Reply-To: <20171124091448.7649-14-mingo@kernel.org>
On Fri, 24 Nov 2017, Ingo Molnar wrote:
> From: Andy Lutomirski <luto@kernel.org>
> @@ -563,6 +563,13 @@ END(irq_entries_start)
> /* 0(%rsp): ~(interrupt number) */
> .macro interrupt func
> cld
> +
> + testb $3, CS-ORIG_RAX(%rsp)
> + jz 1f
> + SWAPGS
> + call switch_to_thread_stack
> +1:
Yes, that's what I thought it should look like.
> ALLOC_PT_GPREGS_ON_STACK
> SAVE_C_REGS
> SAVE_EXTRA_REGS
> @@ -572,12 +579,8 @@ END(irq_entries_start)
> jz 1f
If you change that to 2f and adjust the label down there it gets even
simpler to read. I know it works, but I still find it disturbing.
> /*
> - * IRQ from user mode. Switch to kernel gsbase and inform context
> - * tracking that we're in kernel mode.
> - */
> - SWAPGS
> -
> - /*
> + * IRQ from user mode.
> + *
> * We need to tell lockdep that IRQs are off. We can't do this until
> * we fix gsbase, and we should do it before enter_from_user_mode
> * (which can take locks). Since TRACE_IRQS_OFF idempotent,
> @@ -831,6 +834,32 @@ apicinterrupt IRQ_WORK_VECTOR irq_work_interrupt smp_irq_work_interrupt
> */
> #define CPU_TSS_IST(x) PER_CPU_VAR(cpu_tss) + (TSS_ist + ((x) - 1) * 8)
>
> +/*
> + * Switch to the thread stack. This is called with the IRET frame and
> + * orig_ax on the stack. (That is, RDI..R12 are not on the stack and
> + * space has not been allocated for them.)
> + */
> +ENTRY(switch_to_thread_stack)
> + UNWIND_HINT_FUNC
> +
> + pushq %rdi
> + movq %rsp, %rdi
> + movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
> + UNWIND_HINT sp_offset=16 sp_reg=ORC_REG_DI
> +
> + pushq 7*8(%rdi) /* regs->ss */
> + pushq 6*8(%rdi) /* regs->rsp */
> + pushq 5*8(%rdi) /* regs->eflags */
> + pushq 4*8(%rdi) /* regs->cs */
> + pushq 3*8(%rdi) /* regs->ip */
> + pushq 2*8(%rdi) /* regs->orig_ax */
> + pushq 8(%rdi) /* return address */
> + UNWIND_HINT_FUNC
> +
> + movq (%rdi), %rdi
> + ret
> +END(switch_to_thread_stack)
Much nicer.
> .macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1
> ENTRY(\sym)
> UNWIND_HINT_IRET_REGS offset=\has_error_code*8
> @@ -848,11 +877,12 @@ ENTRY(\sym)
>
> ALLOC_PT_GPREGS_ON_STACK
>
> - .if \paranoid
> - .if \paranoid == 1
> + .if \paranoid < 2
> testb $3, CS(%rsp) /* If coming from userspace, switch stacks */
> - jnz 1f
> + jnz .Lfrom_usermode_switch_stack_\@
> .endif
> +
> + .if \paranoid
> call paranoid_entry
> .else
> call error_entry
> @@ -894,20 +924,15 @@ ENTRY(\sym)
> jmp error_exit
> .endif
>
> - .if \paranoid == 1
> + .if \paranoid < 2
> /*
> - * Paranoid entry from userspace. Switch stacks and treat it
> + * Entry from userspace. Switch stacks and treat it
> * as a normal entry. This means that paranoid handlers
> * run in real process context if user_mode(regs).
> */
> -1:
> +.Lfrom_usermode_switch_stack_\@:
> call error_entry
>
> -
> - movq %rsp, %rdi /* pt_regs pointer */
> - call sync_regs
> - movq %rax, %rsp /* switch stack */
> -
> movq %rsp, %rdi /* pt_regs pointer */
>
> .if \has_error_code
> @@ -1170,6 +1195,14 @@ ENTRY(error_entry)
> SWAPGS
>
> .Lerror_entry_from_usermode_after_swapgs:
> + /* Put us onto the real thread stack. */
> + popq %r12 /* save return addr in %12 */
> + movq %rsp, %rdi /* arg0 = pt_regs pointer */
> + call sync_regs
> + movq %rax, %rsp /* switch stack */
> + ENCODE_FRAME_POINTER
> + pushq %r12
> +
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
next prev parent reply other threads:[~2017-11-24 11:27 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-24 9:14 [PATCH 00/43] x86 entry-stack and Kaiser series, 2017/11/24 version Ingo Molnar
2017-11-24 9:14 ` [PATCH 01/43] x86/decoder: Add new TEST instruction pattern Ingo Molnar
2017-11-24 10:38 ` Borislav Petkov
2017-12-02 7:39 ` Robert Elliott (Persistent Memory)
2017-11-24 9:14 ` [PATCH 02/43] x86/entry/64: Allocate and enable the SYSENTER stack Ingo Molnar
2017-11-24 9:14 ` [PATCH 03/43] x86/dumpstack: Add get_stack_info() support for " Ingo Molnar
2017-11-24 9:14 ` [PATCH 04/43] x86/gdt: Put per-cpu GDT remaps in ascending order Ingo Molnar
2017-11-24 9:14 ` [PATCH 05/43] x86/fixmap: Generalize the GDT fixmap mechanism Ingo Molnar
2017-11-24 11:00 ` Borislav Petkov
2017-11-24 9:14 ` [PATCH 06/43] x86/kasan/64: Teach KASAN about the cpu_entry_area Ingo Molnar
2017-11-24 9:14 ` [PATCH 07/43] x86/entry: Fix assumptions that the HW TSS is at the beginning of cpu_tss Ingo Molnar
2017-11-24 9:14 ` [PATCH 08/43] x86/dumpstack: Handle stack overflow on all stacks Ingo Molnar
2017-11-24 9:14 ` [PATCH 09/43] x86/entry: Move SYSENTER_stack to the beginning of struct tss_struct Ingo Molnar
2017-11-24 11:44 ` Borislav Petkov
2017-11-24 9:14 ` [PATCH 10/43] x86/entry: Remap the TSS into the cpu entry area Ingo Molnar
2017-11-24 9:14 ` [PATCH 11/43] x86/entry/64: Separate cpu_current_top_of_stack from TSS.sp0 Ingo Molnar
2017-11-24 14:19 ` Borislav Petkov
2017-11-24 9:14 ` [PATCH 12/43] x86/espfix/64: Stop assuming that pt_regs is on the entry stack Ingo Molnar
2017-11-24 9:14 ` [PATCH 13/43] x86/entry/64: Use a percpu trampoline stack for IDT entries Ingo Molnar
2017-11-24 11:27 ` Thomas Gleixner [this message]
2017-11-24 9:14 ` [PATCH 14/43] x86/entry/64: Return to userspace from the trampoline stack Ingo Molnar
2017-11-24 13:46 ` Thomas Gleixner
2017-11-24 9:14 ` [PATCH 15/43] x86/entry/64: Create a percpu SYSCALL entry trampoline Ingo Molnar
2017-11-24 13:52 ` Thomas Gleixner
2017-11-24 9:14 ` [PATCH 16/43] x86/irq: Remove an old outdated comment about context tracking races Ingo Molnar
2017-11-24 13:53 ` Thomas Gleixner
2017-11-24 9:14 ` [PATCH 17/43] x86/irq/64: Print the offending IP in the stack overflow warning Ingo Molnar
2017-11-24 14:22 ` Thomas Gleixner
2017-11-24 9:14 ` [PATCH 18/43] x86/entry/64: Move the IST stacks into cpu_entry_area Ingo Molnar
2017-11-24 14:23 ` Thomas Gleixner
2017-11-24 9:14 ` [PATCH 19/43] x86/entry/64: Remove the SYSENTER stack canary Ingo Molnar
2017-11-24 14:23 ` Thomas Gleixner
2017-11-24 9:14 ` [PATCH 20/43] x86/entry: Clean up SYSENTER_stack code Ingo Molnar
2017-11-24 14:24 ` Thomas Gleixner
2017-11-24 9:14 ` [PATCH 21/43] x86/mm/kaiser: Disable global pages by default with KAISER Ingo Molnar
2017-11-24 9:14 ` [PATCH 22/43] x86/mm/kaiser: Prepare assembly for entry/exit CR3 switching Ingo Molnar
2017-11-24 12:05 ` Peter Zijlstra
2017-11-24 12:17 ` Ingo Molnar
2017-11-24 12:45 ` Peter Zijlstra
2017-11-24 13:04 ` Thomas Gleixner
2017-11-24 9:14 ` [PATCH 23/43] x86/mm/kaiser: Introduce user-mapped per-cpu areas Ingo Molnar
2017-11-24 9:14 ` [PATCH 24/43] x86/mm/kaiser: Mark per-cpu data structures required for entry/exit Ingo Molnar
2017-11-24 9:14 ` [PATCH 25/43] x86/mm/kaiser: Unmap kernel from userspace page tables (core patch) Ingo Molnar
2017-11-24 12:13 ` Peter Zijlstra
2017-11-24 13:46 ` Ingo Molnar
2017-11-24 12:16 ` Peter Zijlstra
2017-11-24 16:33 ` Dave Hansen
2017-11-26 15:13 ` Ingo Molnar
2017-11-24 13:30 ` Peter Zijlstra
2017-11-26 15:15 ` Ingo Molnar
2017-11-27 8:59 ` [PATCH] x86/mm/kaiser: Use the other page_table_lock pattern Peter Zijlstra
2017-11-27 8:59 ` [PATCH] mm: Unify page_table_lock allocation pattern Peter Zijlstra
2017-11-24 9:14 ` [PATCH 26/43] x86/mm/kaiser: Allow NX poison to be set in p4d/pgd Ingo Molnar
2017-11-24 9:14 ` [PATCH 27/43] x86/mm/kaiser: Make sure static PGDs are 8k in size Ingo Molnar
2017-11-24 9:14 ` [PATCH 28/43] x86/mm/kaiser: Map CPU entry area Ingo Molnar
2017-11-24 13:43 ` Peter Zijlstra
2017-11-24 9:14 ` [PATCH 29/43] x86/mm/kaiser: Map dynamically-allocated LDTs Ingo Molnar
2017-11-24 9:14 ` [PATCH 30/43] x86/mm/kaiser: Map espfix structures Ingo Molnar
2017-11-24 13:47 ` Peter Zijlstra
2017-11-24 16:17 ` Andy Lutomirski
2017-11-27 9:14 ` Peter Zijlstra
2017-11-27 15:35 ` Peter Zijlstra
2017-11-24 9:14 ` [PATCH 31/43] x86/mm/kaiser: Map entry stack variable Ingo Molnar
2017-11-24 9:14 ` [PATCH 32/43] x86/mm/kaiser: Map virtually-addressed performance monitoring buffers Ingo Molnar
2017-11-24 9:14 ` [PATCH 33/43] x86/mm: Move CR3 construction functions Ingo Molnar
2017-11-24 9:14 ` [PATCH 34/43] x86/mm: Remove hard-coded ASID limit checks Ingo Molnar
2017-11-24 9:14 ` [PATCH 35/43] x86/mm: Put mmu-to-h/w ASID translation in one place Ingo Molnar
2017-11-24 9:14 ` [PATCH 36/43] x86/mm: Allow flushing for future ASID switches Ingo Molnar
2017-11-24 9:14 ` [PATCH 37/43] x86/mm/kaiser: Use PCID feature to make user and kernel switches faster Ingo Molnar
2017-11-24 9:14 ` [PATCH 38/43] x86/mm/kaiser: Disable native VSYSCALL Ingo Molnar
2017-11-24 9:14 ` [PATCH 39/43] x86/mm/kaiser: Add debugfs file to turn KAISER on/off at runtime Ingo Molnar
2017-11-24 9:14 ` [PATCH 40/43] x86/mm/kaiser: Add a function to check for KAISER being enabled Ingo Molnar
2017-11-24 9:14 ` [PATCH 41/43] x86/mm/kaiser: Un-poison PGDs at runtime Ingo Molnar
2017-11-24 9:14 ` [PATCH 42/43] x86/mm/kaiser: Allow KAISER to be enabled/disabled " Ingo Molnar
2017-11-24 9:14 ` [PATCH 43/43] x86/mm/kaiser: Add Kconfig Ingo Molnar
2017-11-24 13:55 ` [PATCH 00/43] x86 entry-stack and Kaiser series, 2017/11/24 version Ingo Molnar
2017-11-24 15:23 ` Thomas Gleixner
2017-11-24 17:19 ` Ingo Molnar
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