ARM: fix a cockup in 48be69a02
(ARM: move signal handlers into a vdso-like page)
Unfortunately, I never committed the fix to a nasty oops which can occur as a result of that commit: ------------[ cut here ]------------ kernel BUG at /home/olof/work/batch/include/linux/mm.h:414! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM Modules linked in: CPU: 0 PID: 490 Comm: killall5 Not tainted 3.11.0-rc3-00288-gabe0308 #53 task: e90acac0 ti: e9be8000 task.ti: e9be8000 PC is at special_mapping_fault+0xa4/0xc4 LR is at __do_fault+0x68/0x48c This doesn't show up unless you do quite a bit of testing; a simple boot test does not do this, so all my nightly tests were passing fine. The reason for this is that install_special_mapping() expects the page array to stick around, and as this was only inserting one page which was stored on the kernel stack, that's why this was blowing up. Reported-by: Olof Johansson <olof@lixom.net> Tested-by: Olof Johansson <olof@lixom.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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@ -471,17 +471,18 @@ const char *arch_vma_name(struct vm_area_struct *vma)
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"[sigpage]" : NULL;
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}
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static struct page *signal_page;
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extern struct page *get_signal_page(void);
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int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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{
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struct mm_struct *mm = current->mm;
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struct page *page;
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unsigned long addr;
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int ret;
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page = get_signal_page();
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if (!page)
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if (!signal_page)
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signal_page = get_signal_page();
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if (!signal_page)
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return -ENOMEM;
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down_write(&mm->mmap_sem);
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@ -493,7 +494,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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ret = install_special_mapping(mm, addr, PAGE_SIZE,
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VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
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&page);
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&signal_page);
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if (ret == 0)
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mm->context.sigpage = addr;
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@ -614,35 +614,32 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
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return 0;
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}
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static struct page *signal_page;
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struct page *get_signal_page(void)
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{
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if (!signal_page) {
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unsigned long ptr;
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unsigned offset;
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void *addr;
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unsigned long ptr;
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unsigned offset;
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struct page *page;
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void *addr;
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signal_page = alloc_pages(GFP_KERNEL, 0);
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page = alloc_pages(GFP_KERNEL, 0);
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if (!signal_page)
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return NULL;
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if (!page)
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return NULL;
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addr = page_address(signal_page);
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addr = page_address(page);
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/* Give the signal return code some randomness */
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offset = 0x200 + (get_random_int() & 0x7fc);
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signal_return_offset = offset;
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/* Give the signal return code some randomness */
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offset = 0x200 + (get_random_int() & 0x7fc);
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signal_return_offset = offset;
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/*
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* Copy signal return handlers into the vector page, and
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* set sigreturn to be a pointer to these.
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*/
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memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
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/*
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* Copy signal return handlers into the vector page, and
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* set sigreturn to be a pointer to these.
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*/
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memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
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ptr = (unsigned long)addr + offset;
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flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
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}
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ptr = (unsigned long)addr + offset;
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flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
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return signal_page;
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return page;
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}
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