sparc64: Handle PIO & MEM non-resumable errors.

User processes trying to access an invalid memory address via PIO will
receive a SIGBUS signal instead of causing a panic.  Memory errors will
receive a SIGKILL since a SIGBUS may result in a coredump which may
attempt to repeat the faulting access.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
index 496fa926e1e003ef85fc6ec7303b1db1ea1b8763..d44fb806bbd791e88599fec5c3a1bb161aa4d1e6 100644 (file)
--- a/arch/sparc/kernel/traps_64.c
+++ b/arch/sparc/kernel/traps_64.c
@@ -2051,6 +2051,73 @@ void sun4v_resum_overflow(struct pt_regs *regs)
        atomic_inc(&sun4v_resum_oflow_cnt);
 }
 
+/* Given a set of registers, get the virtual addressi that was being accessed
+ * by the faulting instructions at tpc.
+ */
+static unsigned long sun4v_get_vaddr(struct pt_regs *regs)
+{
+       unsigned int insn;
+
+       if (!copy_from_user(&insn, (void __user *)regs->tpc, 4)) {
+               return compute_effective_address(regs, insn,
+                                                (insn >> 25) & 0x1f);
+       }
+       return 0;
+}
+
+/* Attempt to handle non-resumable errors generated from userspace.
+ * Returns true if the signal was handled, false otherwise.
+ */
+bool sun4v_nonresum_error_user_handled(struct pt_regs *regs,
+                                 struct sun4v_error_entry *ent) {
+
+       unsigned int attrs = ent->err_attrs;
+
+       if (attrs & SUN4V_ERR_ATTRS_MEMORY) {
+               unsigned long addr = ent->err_raddr;
+               siginfo_t info;
+
+               if (addr == ~(u64)0) {
+                       /* This seems highly unlikely to ever occur */
+                       pr_emerg("SUN4V NON-RECOVERABLE ERROR: Memory error detected in unknown location!\n");
+               } else {
+                       unsigned long page_cnt = DIV_ROUND_UP(ent->err_size,
+                                                             PAGE_SIZE);
+
+                       /* Break the unfortunate news. */
+                       pr_emerg("SUN4V NON-RECOVERABLE ERROR: Memory failed at %016lX\n",
+                                addr);
+                       pr_emerg("SUN4V NON-RECOVERABLE ERROR:   Claiming %lu ages.\n",
+                                page_cnt);
+
+                       while (page_cnt-- > 0) {
+                               if (pfn_valid(addr >> PAGE_SHIFT))
+                                       get_page(pfn_to_page(addr >> PAGE_SHIFT));
+                               addr += PAGE_SIZE;
+                       }
+               }
+               info.si_signo = SIGKILL;
+               info.si_errno = 0;
+               info.si_trapno = 0;
+               force_sig_info(info.si_signo, &info, current);
+
+               return true;
+       }
+       if (attrs & SUN4V_ERR_ATTRS_PIO) {
+               siginfo_t info;
+
+               info.si_signo = SIGBUS;
+               info.si_code = BUS_ADRERR;
+               info.si_addr = (void __user *)sun4v_get_vaddr(regs);
+               force_sig_info(info.si_signo, &info, current);
+
+               return true;
+       }
+
+       /* Default to doing nothing */
+       return false;
+}
+
 /* We run with %pil set to PIL_NORMAL_MAX and PSTATE_IE enabled in %pstate.
  * Log the event, clear the first word of the entry, and die.
  */
@@ -2075,6 +2142,12 @@ void sun4v_nonresum_error(struct pt_regs *regs, unsigned long offset)
 
        put_cpu();
 
+       if (!(regs->tstate & TSTATE_PRIV) &&
+           sun4v_nonresum_error_user_handled(regs, &local_copy)) {
+               /* DON'T PANIC: This userspace error was handled. */
+               return;
+       }
+
 #ifdef CONFIG_PCI
        /* Check for the special PCI poke sequence. */
        if (pci_poke_in_progress && pci_poke_cpu == cpu) {