From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Lutomirski <luto@kernel.org>, x86@kernel.org
Cc: LKML <linux-kernel@vger.kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Brian Gerst <brgerst@gmail.com>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH v4 7/9] kentry: Add debugging checks for proper kentry API usage
Date: Fri, 19 Mar 2021 19:16:48 +0100 [thread overview]
Message-ID: <87h7l757qn.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <87pmzv5d90.fsf@nanos.tec.linutronix.de>
On Fri, Mar 19 2021 at 17:17, Thomas Gleixner wrote:
> On Wed, Mar 17 2021 at 11:12, Andy Lutomirski wrote:
>> +
>> +#define DEBUG_ENTRY_WARN_ONCE(condition, format...) do {} while (0)
>
> So we have a stub for !DEBUG
>
>> +static __always_inline void kentry_cpu_depth_add(unsigned int n) {}
>> +static void kentry_cpu_depth_check(unsigned int n) {}
>> +static __always_inline void kentry_cpu_depth_sub(unsigned int n) {}
>> +
>> +#endif
>> +
>> /* See comment for enter_from_user_mode() in entry-common.h */
>> static __always_inline void __enter_from_user_mode(struct pt_regs *regs)
>> {
>> + kentry_cpu_depth_add(1);
>> arch_check_user_regs(regs);
>> lockdep_hardirqs_off(CALLER_ADDR0);
>>
>> @@ -22,6 +78,14 @@ static __always_inline void __enter_from_user_mode(struct pt_regs *regs)
>>
>> instrumentation_begin();
>> trace_hardirqs_off_finish();
>> +
>> +#ifdef CONFIG_DEBUG_ENTRY
>
> Why do we need that #ifdeffery all over the place?
>
>> + DEBUG_ENTRY_WARN_ONCE(
>> + this_cpu_read(kentry_cpu_depth) != 1,
>> + "kentry: __enter_from_user_mode() called while kentry thought the CPU was in the kernel (%u)",
>> + this_cpu_read(kentry_cpu_depth));
Because you directly access kentry_cpu_depth which makes the compiler
unhappy.
And of course at the other place where you guard it with IS_ENABLED() it
fails to build with CONFIG_DEBUG_ENTRY=n
kernel/entry/common.c:158:10: error: ‘struct task_struct’ has no member named ‘kentry_in_syscall’
current->kentry_in_syscall = true;
This is V4 of this series... Oh well.
tglx
next prev parent reply other threads:[~2021-03-19 18:17 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-17 18:12 [PATCH v4 0/9] kentry: A stable bugfix and a bunch of improvements Andy Lutomirski
2021-03-17 18:12 ` [PATCH v4 1/9] x86/dumpstack: Remove unnecessary range check fetching opcode bytes Andy Lutomirski
2021-03-17 18:12 ` [PATCH v4 2/9] x86/kthread,dumpstack: Set task_pt_regs->cs.RPL=3 for kernel threads Andy Lutomirski
2021-03-18 0:36 ` Josh Poimboeuf
2021-03-17 18:12 ` [PATCH v4 3/9] x86/entry: Convert ret_from_fork to C Andy Lutomirski
2021-03-18 0:38 ` Josh Poimboeuf
2021-03-19 16:05 ` Thomas Gleixner
2021-03-17 18:12 ` [PATCH v4 4/9] kentry: Simplify the common syscall API Andy Lutomirski
2021-03-19 16:09 ` Thomas Gleixner
2021-03-19 18:07 ` Thomas Gleixner
2021-03-17 18:12 ` [PATCH v4 5/9] kentry: Remove enter_from/exit_to_user_mode() Andy Lutomirski
2021-03-19 18:08 ` Thomas Gleixner
2021-03-17 18:12 ` [PATCH v4 6/9] entry: Make CONFIG_DEBUG_ENTRY available outside x86 Andy Lutomirski
2021-03-17 18:12 ` [PATCH v4 7/9] kentry: Add debugging checks for proper kentry API usage Andy Lutomirski
2021-03-19 16:17 ` Thomas Gleixner
2021-03-19 18:16 ` Thomas Gleixner [this message]
2021-03-17 18:12 ` [PATCH v4 8/9] kentry: Check that syscall entries and syscall exits match Andy Lutomirski
2021-03-17 18:12 ` [PATCH v4 9/9] kentry: Verify kentry state in instrumentation_begin/end() Andy Lutomirski
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