From 7b2d0dbac4890c8ca4a8acc57709639fc8b158e9 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 12 Feb 2016 13:02:11 -0800 Subject: [PATCH] x86/mm/pkeys: Pass VMA down in to fault signal generation code During a page fault, we look up the VMA to ensure that the fault is in a region with a valid mapping. But, in the top-level page fault code we don't need the VMA for much else. Once we have decided that an access is bad, we are going to send a signal no matter what and do not need the VMA any more. So we do not pass it down in to the signal generation code. But, for protection keys, we need the VMA. It tells us *which* protection key we violated if we get a PF_PK. So, we need to pass the VMA down and fill in siginfo->si_pkey. Signed-off-by: Dave Hansen Reviewed-by: Thomas Gleixner Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Rik van Riel Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20160212210211.AD3B36A3@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/mm/fault.c | 50 +++++++++++++++++++++++++-------------------- 1 file changed, 28 insertions(+), 22 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 9f72f9c9be4f..3c51c66b65fc 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -171,7 +171,8 @@ is_prefetch(struct pt_regs *regs, unsigned long error_code, unsigned long addr) static void force_sig_info_fault(int si_signo, int si_code, unsigned long address, - struct task_struct *tsk, int fault) + struct task_struct *tsk, struct vm_area_struct *vma, + int fault) { unsigned lsb = 0; siginfo_t info; @@ -656,6 +657,8 @@ no_context(struct pt_regs *regs, unsigned long error_code, struct task_struct *tsk = current; unsigned long flags; int sig; + /* No context means no VMA to pass down */ + struct vm_area_struct *vma = NULL; /* Are we prepared to handle this kernel fault? */ if (fixup_exception(regs)) { @@ -679,7 +682,8 @@ no_context(struct pt_regs *regs, unsigned long error_code, tsk->thread.cr2 = address; /* XXX: hwpoison faults will set the wrong code. */ - force_sig_info_fault(signal, si_code, address, tsk, 0); + force_sig_info_fault(signal, si_code, address, + tsk, vma, 0); } /* @@ -756,7 +760,8 @@ show_signal_msg(struct pt_regs *regs, unsigned long error_code, static void __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, - unsigned long address, int si_code) + unsigned long address, struct vm_area_struct *vma, + int si_code) { struct task_struct *tsk = current; @@ -799,7 +804,7 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_PF; - force_sig_info_fault(SIGSEGV, si_code, address, tsk, 0); + force_sig_info_fault(SIGSEGV, si_code, address, tsk, vma, 0); return; } @@ -812,14 +817,14 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, static noinline void bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, - unsigned long address) + unsigned long address, struct vm_area_struct *vma) { - __bad_area_nosemaphore(regs, error_code, address, SEGV_MAPERR); + __bad_area_nosemaphore(regs, error_code, address, vma, SEGV_MAPERR); } static void __bad_area(struct pt_regs *regs, unsigned long error_code, - unsigned long address, int si_code) + unsigned long address, struct vm_area_struct *vma, int si_code) { struct mm_struct *mm = current->mm; @@ -829,25 +834,25 @@ __bad_area(struct pt_regs *regs, unsigned long error_code, */ up_read(&mm->mmap_sem); - __bad_area_nosemaphore(regs, error_code, address, si_code); + __bad_area_nosemaphore(regs, error_code, address, vma, si_code); } static noinline void bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address) { - __bad_area(regs, error_code, address, SEGV_MAPERR); + __bad_area(regs, error_code, address, NULL, SEGV_MAPERR); } static noinline void bad_area_access_error(struct pt_regs *regs, unsigned long error_code, - unsigned long address) + unsigned long address, struct vm_area_struct *vma) { - __bad_area(regs, error_code, address, SEGV_ACCERR); + __bad_area(regs, error_code, address, vma, SEGV_ACCERR); } static void do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address, - unsigned int fault) + struct vm_area_struct *vma, unsigned int fault) { struct task_struct *tsk = current; int code = BUS_ADRERR; @@ -874,12 +879,13 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address, code = BUS_MCEERR_AR; } #endif - force_sig_info_fault(SIGBUS, code, address, tsk, fault); + force_sig_info_fault(SIGBUS, code, address, tsk, vma, fault); } static noinline void mm_fault_error(struct pt_regs *regs, unsigned long error_code, - unsigned long address, unsigned int fault) + unsigned long address, struct vm_area_struct *vma, + unsigned int fault) { if (fatal_signal_pending(current) && !(error_code & PF_USER)) { no_context(regs, error_code, address, 0, 0); @@ -903,9 +909,9 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code, } else { if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON| VM_FAULT_HWPOISON_LARGE)) - do_sigbus(regs, error_code, address, fault); + do_sigbus(regs, error_code, address, vma, fault); else if (fault & VM_FAULT_SIGSEGV) - bad_area_nosemaphore(regs, error_code, address); + bad_area_nosemaphore(regs, error_code, address, vma); else BUG(); } @@ -1119,7 +1125,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code, * Don't take the mm semaphore here. If we fixup a prefetch * fault we could otherwise deadlock: */ - bad_area_nosemaphore(regs, error_code, address); + bad_area_nosemaphore(regs, error_code, address, NULL); return; } @@ -1132,7 +1138,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code, pgtable_bad(regs, error_code, address); if (unlikely(smap_violation(error_code, regs))) { - bad_area_nosemaphore(regs, error_code, address); + bad_area_nosemaphore(regs, error_code, address, NULL); return; } @@ -1141,7 +1147,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code, * in a region with pagefaults disabled then we must not take the fault */ if (unlikely(faulthandler_disabled() || !mm)) { - bad_area_nosemaphore(regs, error_code, address); + bad_area_nosemaphore(regs, error_code, address, NULL); return; } @@ -1185,7 +1191,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code, if (unlikely(!down_read_trylock(&mm->mmap_sem))) { if ((error_code & PF_USER) == 0 && !search_exception_tables(regs->ip)) { - bad_area_nosemaphore(regs, error_code, address); + bad_area_nosemaphore(regs, error_code, address, NULL); return; } retry: @@ -1233,7 +1239,7 @@ retry: */ good_area: if (unlikely(access_error(error_code, vma))) { - bad_area_access_error(regs, error_code, address); + bad_area_access_error(regs, error_code, address, vma); return; } @@ -1271,7 +1277,7 @@ good_area: up_read(&mm->mmap_sem); if (unlikely(fault & VM_FAULT_ERROR)) { - mm_fault_error(regs, error_code, address, fault); + mm_fault_error(regs, error_code, address, vma, fault); return; } -- 2.30.2