96 lines
3.5 KiB
Diff
96 lines
3.5 KiB
Diff
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From bcc537efea6e5aac805c8c3244a32b7488c43df8 Mon Sep 17 00:00:00 2001
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From: "Yadi.hu" <yadi.hu@windriver.com>
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Date: Wed, 10 Dec 2014 10:32:09 +0800
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Subject: [PATCH 252/365] ARM: enable irq in translation/section permission
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fault handlers
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Probably happens on all ARM, with
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CONFIG_PREEMPT_RT_FULL
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CONFIG_DEBUG_ATOMIC_SLEEP
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This simple program....
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int main() {
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*((char*)0xc0001000) = 0;
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};
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[ 512.742724] BUG: sleeping function called from invalid context at kernel/rtmutex.c:658
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[ 512.743000] in_atomic(): 0, irqs_disabled(): 128, pid: 994, name: a
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[ 512.743217] INFO: lockdep is turned off.
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[ 512.743360] irq event stamp: 0
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[ 512.743482] hardirqs last enabled at (0): [< (null)>] (null)
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[ 512.743714] hardirqs last disabled at (0): [<c0426370>] copy_process+0x3b0/0x11c0
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[ 512.744013] softirqs last enabled at (0): [<c0426370>] copy_process+0x3b0/0x11c0
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[ 512.744303] softirqs last disabled at (0): [< (null)>] (null)
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[ 512.744631] [<c041872c>] (unwind_backtrace+0x0/0x104)
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[ 512.745001] [<c09af0c4>] (dump_stack+0x20/0x24)
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[ 512.745355] [<c0462490>] (__might_sleep+0x1dc/0x1e0)
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[ 512.745717] [<c09b6770>] (rt_spin_lock+0x34/0x6c)
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[ 512.746073] [<c0441bf0>] (do_force_sig_info+0x34/0xf0)
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[ 512.746457] [<c0442668>] (force_sig_info+0x18/0x1c)
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[ 512.746829] [<c041d880>] (__do_user_fault+0x9c/0xd8)
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[ 512.747185] [<c041d938>] (do_bad_area+0x7c/0x94)
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[ 512.747536] [<c041d990>] (do_sect_fault+0x40/0x48)
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[ 512.747898] [<c040841c>] (do_DataAbort+0x40/0xa0)
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[ 512.748181] Exception stack(0xecaa1fb0 to 0xecaa1ff8)
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Oxc0000000 belongs to kernel address space, user task can not be
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allowed to access it. For above condition, correct result is that
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test case should receive a “segment fault” and exits but not stacks.
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the root cause is commit 02fe2845d6a8 ("avoid enabling interrupts in
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prefetch/data abort handlers"),it deletes irq enable block in Data
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abort assemble code and move them into page/breakpiont/alignment fault
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handlers instead. But author does not enable irq in translation/section
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permission fault handlers. ARM disables irq when it enters exception/
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interrupt mode, if kernel doesn't enable irq, it would be still disabled
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during translation/section permission fault.
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We see the above splat because do_force_sig_info is still called with
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IRQs off, and that code eventually does a:
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spin_lock_irqsave(&t->sighand->siglock, flags);
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As this is architecture independent code, and we've not seen any other
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need for other arch to have the siglock converted to raw lock, we can
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conclude that we should enable irq for ARM translation/section
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permission exception.
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Signed-off-by: Yadi.hu <yadi.hu@windriver.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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arch/arm/mm/fault.c | 6 ++++++
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1 file changed, 6 insertions(+)
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diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
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index 9453c92f9f8f..ef03c9d6bc5b 100644
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--- a/arch/arm/mm/fault.c
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+++ b/arch/arm/mm/fault.c
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@@ -436,6 +436,9 @@ do_translation_fault(unsigned long addr, unsigned int fsr,
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if (addr < TASK_SIZE)
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return do_page_fault(addr, fsr, regs);
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+ if (interrupts_enabled(regs))
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+ local_irq_enable();
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+
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if (user_mode(regs))
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goto bad_area;
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@@ -503,6 +506,9 @@ do_translation_fault(unsigned long addr, unsigned int fsr,
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static int
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do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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+ if (interrupts_enabled(regs))
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+ local_irq_enable();
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+
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do_bad_area(addr, fsr, regs);
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return 0;
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}
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--
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2.28.0
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