From: Andy Lutomirski <luto@kernel.org>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"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 16/21] x86/entry/64: Use a per-CPU trampoline stack for IDT entries
Date: Fri, 1 Dec 2017 09:44:41 -0800 [thread overview]
Message-ID: <CALCETrUnaRZd1t-XX-Ax4n_hqj+o81OXO3DRG4OBY2g=qo4gHg@mail.gmail.com> (raw)
In-Reply-To: <305ed448-6f8e-eecd-d120-546efc185443@linux.intel.com>
> On Dec 1, 2017, at 9:06 AM, Dave Hansen <dave.hansen@linux.intel.com> wrote:
>
>> On 11/27/2017 02:45 AM, Ingo Molnar wrote:
>> --- a/arch/x86/kernel/cpu/common.c
>> +++ b/arch/x86/kernel/cpu/common.c
>> @@ -1645,11 +1645,13 @@ void cpu_init(void)
>> setup_cpu_entry_area(cpu);
>>
>> /*
>> - * Initialize the TSS. Don't bother initializing sp0, as the initial
>> - * task never enters user mode.
>> + * Initialize the TSS. sp0 points to the entry trampoline stack
>> + * regardless of what task is running.
>> */
>> set_tss_desc(cpu, &get_cpu_entry_area(cpu)->tss.x86_tss);
>> load_TR_desc();
>> + load_sp0((unsigned long)&get_cpu_entry_area(cpu)->tss +
>> + offsetofend(struct tss_struct, SYSENTER_stack));
>>
>> load_mm_ldt(&init_mm);
>
> Does this also mean that our stack dumps will say "<SYSENTER>" in oopses?
Only if we oops while we're on the trampoline stack. If the oops is
due to a bug that isn't in the entry code, then we won't see it.
>
>> [ 30.811750] CR2: fffffffffdeb2f98 CR3: 0000000423fae001 CR4: 00000000001607e0
>> [ 30.819712] Call Trace:
>> [ 30.822442] <SYSENTER>
>> [ 30.825170] trace_hardirqs_on_thunk+0x1c/0x1c
> ...
>> [ 31.000571] R13: 0000000000000050 R14: 0000000000000076 R15: 00007f59f76f2d60
>> [ 31.008533] </SYSENTER>
>
> Should we change that string to something more descriptive?
I suppose we could rename it to "ENTRY_TRAMPOLINE" or something like that.
next prev parent reply other threads:[~2017-12-01 17:45 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-27 10:45 [PATCH 00/21] Preparatory patches for x86 KAISER support Ingo Molnar
2017-11-27 10:45 ` [PATCH 01/21] x86/unwinder/orc: Don't bail on stack overflow Ingo Molnar
2017-11-27 14:47 ` Borislav Petkov
2017-11-27 10:45 ` [PATCH 02/21] x86/unwinder: Handle stack overflows more gracefully Ingo Molnar
2017-11-27 17:36 ` Borislav Petkov
2017-11-28 4:55 ` Josh Poimboeuf
2017-11-27 10:45 ` [PATCH 03/21] x86/irq: Remove an old outdated comment about context tracking races Ingo Molnar
2017-11-27 10:45 ` [PATCH 04/21] x86/irq/64: Print the offending IP in the stack overflow warning Ingo Molnar
2017-11-27 10:45 ` [PATCH 05/21] x86/entry/64: Allocate and enable the SYSENTER stack Ingo Molnar
2017-11-27 10:45 ` [PATCH 06/21] x86/dumpstack: Add get_stack_info() support for " Ingo Molnar
2017-11-27 10:45 ` [PATCH 07/21] x86/entry/gdt: Put per-CPU GDT remaps in ascending order Ingo Molnar
2017-11-27 10:45 ` [PATCH 08/21] x86/mm/fixmap: Generalize the GDT fixmap mechanism, introduce 'struct cpu_entry_area' Ingo Molnar
2017-11-27 10:45 ` [PATCH 09/21] x86/kasan/64: Teach KASAN about the cpu_entry_area Ingo Molnar
2017-11-27 10:45 ` [PATCH 10/21] x86/entry: Fix assumptions that the HW TSS is at the beginning of cpu_tss Ingo Molnar
2017-11-27 10:45 ` [PATCH 11/21] x86/dumpstack: Handle stack overflow on all stacks Ingo Molnar
2017-11-27 19:26 ` Linus Torvalds
2017-11-28 4:29 ` Josh Poimboeuf
2017-11-28 5:29 ` Andy Lutomirski
2017-11-28 18:15 ` Josh Poimboeuf
2017-11-27 10:45 ` [PATCH 12/21] x86/entry: Move SYSENTER_stack to the beginning of struct tss_struct Ingo Molnar
2017-11-27 10:45 ` [PATCH 13/21] x86/entry: Remap the TSS into the CPU entry area Ingo Molnar
2017-11-27 10:45 ` [PATCH 14/21] x86/entry/64: Separate cpu_current_top_of_stack from TSS.sp0 Ingo Molnar
2017-11-27 10:45 ` [PATCH 15/21] x86/espfix/64: Stop assuming that pt_regs is on the entry stack Ingo Molnar
2017-11-27 10:45 ` [PATCH 16/21] x86/entry/64: Use a per-CPU trampoline stack for IDT entries Ingo Molnar
2017-12-01 17:06 ` Dave Hansen
2017-12-01 17:44 ` Andy Lutomirski [this message]
2017-12-01 21:21 ` Dave Hansen
2017-12-01 21:59 ` Andy Lutomirski
2017-12-02 6:41 ` Kevin Easton
2017-11-27 10:45 ` [PATCH 17/21] x86/entry/64: Return to userspace from the trampoline stack Ingo Molnar
2017-11-27 10:45 ` [PATCH 18/21] x86/entry/64: Create a per-CPU SYSCALL entry trampoline Ingo Molnar
2017-11-27 10:45 ` [PATCH 19/21] x86/entry/64: Move the IST stacks into 'struct cpu_entry_area' Ingo Molnar
2017-11-27 10:45 ` [PATCH 20/21] x86/entry/64: Remove the SYSENTER stack canary Ingo Molnar
2017-11-27 10:45 ` [PATCH 21/21] x86/entry: Clean up the SYSENTER_stack code Ingo Molnar
2017-12-01 17:59 ` Borislav Petkov
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