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ARM: 8043/1: uprobes need icache flush after xol write
After instruction write into xol area, on ARM V7 architecture code need to flush dcache and icache to sync them up for given set of addresses. Having just 'flush_dcache_page(page)' call is not enough - it is possible to have stale instruction sitting in icache for given xol area slot address. Introduce arch_uprobe_ixol_copy weak function that by default calls uprobes copy_to_page function and than flush_dcache_page function and on ARM define new one that handles xol slot copy in ARM specific way flush_uprobe_xol_access function shares/reuses implementation with/of flush_ptrace_access function and takes care of writing instruction to user land address space on given variety of different cache types on ARM CPUs. Because flush_uprobe_xol_access does not have vma around flush_ptrace_access was split into two parts. First that retrieves set of condition from vma and common that receives those conditions as flags. Note ARM cache flush function need kernel address through which instruction write happened, so instead of using uprobes copy_to_page function changed code to explicitly map page and do memcpy. Note arch_uprobe_copy_ixol function, in similar way as copy_to_user_page function, has preempt_disable/preempt_enable. Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org> Acked-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: David A. Long <dave.long@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
parent
166aaf3966
commit
72e6ae285a
5 changed files with 70 additions and 13 deletions
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@ -487,4 +487,6 @@ int set_memory_rw(unsigned long addr, int numpages);
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int set_memory_x(unsigned long addr, int numpages);
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int set_memory_nx(unsigned long addr, int numpages);
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void flush_uprobe_xol_access(struct page *page, unsigned long uaddr,
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void *kaddr, unsigned long len);
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#endif
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@ -113,6 +113,26 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
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return 0;
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}
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void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
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void *src, unsigned long len)
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{
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void *xol_page_kaddr = kmap_atomic(page);
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void *dst = xol_page_kaddr + (vaddr & ~PAGE_MASK);
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preempt_disable();
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/* Initialize the slot */
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memcpy(dst, src, len);
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/* flush caches (dcache/icache) */
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flush_uprobe_xol_access(page, vaddr, dst, len);
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preempt_enable();
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kunmap_atomic(xol_page_kaddr);
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}
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int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
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{
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struct uprobe_task *utask = current->utask;
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@ -104,17 +104,20 @@ void flush_cache_page(struct vm_area_struct *vma, unsigned long user_addr, unsig
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#define flush_icache_alias(pfn,vaddr,len) do { } while (0)
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#endif
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#define FLAG_PA_IS_EXEC 1
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#define FLAG_PA_CORE_IN_MM 2
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static void flush_ptrace_access_other(void *args)
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{
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__flush_icache_all();
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}
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static
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void flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
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unsigned long uaddr, void *kaddr, unsigned long len)
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static inline
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void __flush_ptrace_access(struct page *page, unsigned long uaddr, void *kaddr,
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unsigned long len, unsigned int flags)
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{
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if (cache_is_vivt()) {
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if (cpumask_test_cpu(smp_processor_id(), mm_cpumask(vma->vm_mm))) {
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if (flags & FLAG_PA_CORE_IN_MM) {
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unsigned long addr = (unsigned long)kaddr;
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__cpuc_coherent_kern_range(addr, addr + len);
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}
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@ -128,7 +131,7 @@ void flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
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}
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/* VIPT non-aliasing D-cache */
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if (vma->vm_flags & VM_EXEC) {
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if (flags & FLAG_PA_IS_EXEC) {
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unsigned long addr = (unsigned long)kaddr;
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if (icache_is_vipt_aliasing())
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flush_icache_alias(page_to_pfn(page), uaddr, len);
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@ -140,6 +143,26 @@ void flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
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}
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}
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static
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void flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
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unsigned long uaddr, void *kaddr, unsigned long len)
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{
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unsigned int flags = 0;
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if (cpumask_test_cpu(smp_processor_id(), mm_cpumask(vma->vm_mm)))
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flags |= FLAG_PA_CORE_IN_MM;
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if (vma->vm_flags & VM_EXEC)
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flags |= FLAG_PA_IS_EXEC;
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__flush_ptrace_access(page, uaddr, kaddr, len, flags);
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}
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void flush_uprobe_xol_access(struct page *page, unsigned long uaddr,
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void *kaddr, unsigned long len)
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{
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unsigned int flags = FLAG_PA_CORE_IN_MM|FLAG_PA_IS_EXEC;
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__flush_ptrace_access(page, uaddr, kaddr, len, flags);
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}
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/*
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* Copy user data from/to a page which is mapped into a different
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* processes address space. Really, we want to allow our "user
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@ -32,6 +32,7 @@ struct vm_area_struct;
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struct mm_struct;
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struct inode;
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struct notifier_block;
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struct page;
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#define UPROBE_HANDLER_REMOVE 1
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#define UPROBE_HANDLER_MASK 1
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@ -127,6 +128,8 @@ extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned l
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extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs);
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extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs);
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extern bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs);
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extern void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
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void *src, unsigned long len);
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#else /* !CONFIG_UPROBES */
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struct uprobes_state {
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};
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@ -1296,14 +1296,8 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe)
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if (unlikely(!xol_vaddr))
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return 0;
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/* Initialize the slot */
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copy_to_page(area->page, xol_vaddr,
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&uprobe->arch.ixol, sizeof(uprobe->arch.ixol));
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/*
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* We probably need flush_icache_user_range() but it needs vma.
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* This should work on supported architectures too.
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*/
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flush_dcache_page(area->page);
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arch_uprobe_copy_ixol(area->page, xol_vaddr,
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&uprobe->arch.ixol, sizeof(uprobe->arch.ixol));
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return xol_vaddr;
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}
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@ -1346,6 +1340,21 @@ static void xol_free_insn_slot(struct task_struct *tsk)
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}
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}
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void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
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void *src, unsigned long len)
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{
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/* Initialize the slot */
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copy_to_page(page, vaddr, src, len);
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/*
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* We probably need flush_icache_user_range() but it needs vma.
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* This should work on most of architectures by default. If
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* architecture needs to do something different it can define
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* its own version of the function.
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*/
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flush_dcache_page(page);
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}
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/**
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* uprobe_get_swbp_addr - compute address of swbp given post-swbp regs
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* @regs: Reflects the saved state of the task after it has hit a breakpoint
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