sparc64: Fix top-level fault handling bugs.

[ Upstream commit 70ffc6ebaead783ac8dafb1e87df0039bb043596 ]

Make get_user_insn() able to cope with huge PMDs.

Next, make do_fault_siginfo() more robust when get_user_insn() can't
actually fetch the instruction.  In particular, use the MMU announced
fault address when that happens, instead of calling
compute_effective_address() and computing garbage.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 504c062..6ac702f 100644 (file)
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -95,38 +95,51 @@ static unsigned int get_user_insn(unsigned long tpc)
        pte_t *ptep, pte;
        unsigned long pa;
        u32 insn = 0;
-       unsigned long pstate;
 
-       if (pgd_none(*pgdp))
-               goto outret;
+       if (pgd_none(*pgdp) || unlikely(pgd_bad(*pgdp)))
+               goto out;
        pudp = pud_offset(pgdp, tpc);
-       if (pud_none(*pudp))
-               goto outret;
-       pmdp = pmd_offset(pudp, tpc);
-       if (pmd_none(*pmdp))
-               goto outret;
-
-       /* This disables preemption for us as well. */
-       __asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate));
-       __asm__ __volatile__("wrpr %0, %1, %%pstate"
-                               : : "r" (pstate), "i" (PSTATE_IE));
-       ptep = pte_offset_map(pmdp, tpc);
-       pte = *ptep;
-       if (!pte_present(pte))
+       if (pud_none(*pudp) || unlikely(pud_bad(*pudp)))
                goto out;
 
-       pa  = (pte_pfn(pte) << PAGE_SHIFT);
-       pa += (tpc & ~PAGE_MASK);
-
-       /* Use phys bypass so we don't pollute dtlb/dcache. */
-       __asm__ __volatile__("lduwa [%1] %2, %0"
-                            : "=r" (insn)
-                            : "r" (pa), "i" (ASI_PHYS_USE_EC));
+       /* This disables preemption for us as well. */
+       local_irq_disable();
 
+       pmdp = pmd_offset(pudp, tpc);
+       if (pmd_none(*pmdp) || unlikely(pmd_bad(*pmdp)))
+               goto out_irq_enable;
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+       if (pmd_trans_huge(*pmdp)) {
+               if (pmd_trans_splitting(*pmdp))
+                       goto out_irq_enable;
+
+               pa  = pmd_pfn(*pmdp) << PAGE_SHIFT;
+               pa += tpc & ~HPAGE_MASK;
+
+               /* Use phys bypass so we don't pollute dtlb/dcache. */
+               __asm__ __volatile__("lduwa [%1] %2, %0"
+                                    : "=r" (insn)
+                                    : "r" (pa), "i" (ASI_PHYS_USE_EC));
+       } else
+#endif
+       {
+               ptep = pte_offset_map(pmdp, tpc);
+               pte = *ptep;
+               if (pte_present(pte)) {
+                       pa  = (pte_pfn(pte) << PAGE_SHIFT);
+                       pa += (tpc & ~PAGE_MASK);
+
+                       /* Use phys bypass so we don't pollute dtlb/dcache. */
+                       __asm__ __volatile__("lduwa [%1] %2, %0"
+                                            : "=r" (insn)
+                                            : "r" (pa), "i" (ASI_PHYS_USE_EC));
+               }
+               pte_unmap(ptep);
+       }
+out_irq_enable:
+       local_irq_enable();
 out:
-       pte_unmap(ptep);
-       __asm__ __volatile__("wrpr %0, 0x0, %%pstate" : : "r" (pstate));
-outret:
        return insn;
 }
 
@@ -154,7 +167,8 @@ show_signal_msg(struct pt_regs *regs, int sig, int code,
 extern unsigned long compute_effective_address(struct pt_regs *, unsigned int, unsigned int);
 
 static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
-                            unsigned int insn, int fault_code)
+                            unsigned long fault_addr, unsigned int insn,
+                            int fault_code)
 {
        unsigned long addr;
        siginfo_t info;
@@ -162,10 +176,18 @@ static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
        info.si_code = code;
        info.si_signo = sig;
        info.si_errno = 0;
-       if (fault_code & FAULT_CODE_ITLB)
+       if (fault_code & FAULT_CODE_ITLB) {
                addr = regs->tpc;
-       else
-               addr = compute_effective_address(regs, insn, 0);
+       } else {
+               /* If we were able to probe the faulting instruction, use it
+                * to compute a precise fault address.  Otherwise use the fault
+                * time provided address which may only have page granularity.
+                */
+               if (insn)
+                       addr = compute_effective_address(regs, insn, 0);
+               else
+                       addr = fault_addr;
+       }
        info.si_addr = (void __user *) addr;
        info.si_trapno = 0;
 
@@ -240,7 +262,7 @@ static void __kprobes do_kernel_fault(struct pt_regs *regs, int si_code,
                /* The si_code was set to make clear whether
                 * this was a SEGV_MAPERR or SEGV_ACCERR fault.
                 */
-               do_fault_siginfo(si_code, SIGSEGV, regs, insn, fault_code);
+               do_fault_siginfo(si_code, SIGSEGV, regs, address, insn, fault_code);
                return;
        }
 
@@ -492,7 +514,7 @@ do_sigbus:
         * Send a sigbus, regardless of whether we were in kernel
         * or user mode.
         */
-       do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, insn, fault_code);
+       do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, address, insn, fault_code);
 
        /* Kernel mode? Handle exceptions or die */
        if (regs->tstate & TSTATE_PRIV)