[PATCH 4.9 051/172] sparc64: Handle PIO & MEM non-resumable errors.

Greg Kroah-Hartman
2017-07-03T13:42:20Z

From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

[ Upstream commit 047487241ff59374fded8c477f21453681f5995c ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/sparc/kernel/traps_64.c | 73 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 73 insertions(+)

--- 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
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

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) {