diff options
Diffstat (limited to 'features/rt/ARM-enable-irq-in-translation-section-permission-fau.patch')
| -rw-r--r-- | features/rt/ARM-enable-irq-in-translation-section-permission-fau.patch | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/features/rt/ARM-enable-irq-in-translation-section-permission-fau.patch b/features/rt/ARM-enable-irq-in-translation-section-permission-fau.patch new file mode 100644 index 00000000..47dd0be4 --- /dev/null +++ b/features/rt/ARM-enable-irq-in-translation-section-permission-fau.patch @@ -0,0 +1,94 @@ +From ced2a927997124c1cceecd5da04917ad03992490 Mon Sep 17 00:00:00 2001 +From: "Yadi.hu" <yadi.hu@windriver.com> +Date: Wed, 10 Dec 2014 10:32:09 +0800 +Subject: [PATCH 173/191] ARM: enable irq in translation/section permission + fault handlers +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +Probably happens on all ARM, with +CONFIG_PREEMPT_RT +CONFIG_DEBUG_ATOMIC_SLEEP + +This simple program.... + +int main() { + *((char*)0xc0001000) = 0; +}; + +[ 512.742724] BUG: sleeping function called from invalid context at kernel/rtmutex.c:658 +[ 512.743000] in_atomic(): 0, irqs_disabled(): 128, pid: 994, name: a +[ 512.743217] INFO: lockdep is turned off. +[ 512.743360] irq event stamp: 0 +[ 512.743482] hardirqs last enabled at (0): [< (null)>] (null) +[ 512.743714] hardirqs last disabled at (0): [<c0426370>] copy_process+0x3b0/0x11c0 +[ 512.744013] softirqs last enabled at (0): [<c0426370>] copy_process+0x3b0/0x11c0 +[ 512.744303] softirqs last disabled at (0): [< (null)>] (null) +[ 512.744631] [<c041872c>] (unwind_backtrace+0x0/0x104) +[ 512.745001] [<c09af0c4>] (dump_stack+0x20/0x24) +[ 512.745355] [<c0462490>] (__might_sleep+0x1dc/0x1e0) +[ 512.745717] [<c09b6770>] (rt_spin_lock+0x34/0x6c) +[ 512.746073] [<c0441bf0>] (do_force_sig_info+0x34/0xf0) +[ 512.746457] [<c0442668>] (force_sig_info+0x18/0x1c) +[ 512.746829] [<c041d880>] (__do_user_fault+0x9c/0xd8) +[ 512.747185] [<c041d938>] (do_bad_area+0x7c/0x94) +[ 512.747536] [<c041d990>] (do_sect_fault+0x40/0x48) +[ 512.747898] [<c040841c>] (do_DataAbort+0x40/0xa0) +[ 512.748181] Exception stack(0xecaa1fb0 to 0xecaa1ff8) + +Oxc0000000 belongs to kernel address space, user task can not be +allowed to access it. For above condition, correct result is that +test case should receive a “segment fault” and exits but not stacks. + +the root cause is commit 02fe2845d6a8 ("avoid enabling interrupts in +prefetch/data abort handlers"),it deletes irq enable block in Data +abort assemble code and move them into page/breakpiont/alignment fault +handlers instead. But author does not enable irq in translation/section +permission fault handlers. ARM disables irq when it enters exception/ +interrupt mode, if kernel doesn't enable irq, it would be still disabled +during translation/section permission fault. + +We see the above splat because do_force_sig_info is still called with +IRQs off, and that code eventually does a: + + spin_lock_irqsave(&t->sighand->siglock, flags); + +As this is architecture independent code, and we've not seen any other +need for other arch to have the siglock converted to raw lock, we can +conclude that we should enable irq for ARM translation/section +permission exception. + +Signed-off-by: Yadi.hu <yadi.hu@windriver.com> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + arch/arm/mm/fault.c | 6 ++++++ + 1 file changed, 6 insertions(+) + +diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c +index da78740faf7b..07f79e533a29 100644 +--- a/arch/arm/mm/fault.c ++++ b/arch/arm/mm/fault.c +@@ -400,6 +400,9 @@ do_translation_fault(unsigned long addr, unsigned int fsr, + if (addr < TASK_SIZE) + return do_page_fault(addr, fsr, regs); + ++ if (interrupts_enabled(regs)) ++ local_irq_enable(); ++ + if (user_mode(regs)) + goto bad_area; + +@@ -479,6 +482,9 @@ do_translation_fault(unsigned long addr, unsigned int fsr, + static int + do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) + { ++ if (interrupts_enabled(regs)) ++ local_irq_enable(); ++ + do_bad_area(addr, fsr, regs); + return 0; + } +-- +2.19.1 + |