arm64: hwpoison: add VM_FAULT_HWPOISON[_LARGE] handling

Add VM_FAULT_HWPOISON[_LARGE] handling to the arm64 page fault
handler. Handling of VM_FAULT_HWPOISON[_LARGE] is very similar
to VM_FAULT_OOM, the only difference is that a different si_code
(BUS_MCEERR_AR) is passed to user space and si_addr_lsb field is
initialized.

Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org>
Signed-off-by: Tyler Baicar <tbaicar@codeaurora.org>
(fix new __do_user_fault call-site)
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Steve Capper <steve.capper@arm.com>
Tested-by: Manoj Iyer <manoj.iyer@canonical.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 19 insertions, 3 deletions

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 222427ae23d6..d73e7f1fe184 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -31,6 +31,7 @@
 #include <linux/highmem.h>
 #include <linux/perf_event.h>
 #include <linux/preempt.h>
+#include <linux/hugetlb.h>
 
 #include <asm/bug.h>
 #include <asm/cpufeature.h>
@@ -256,10 +257,11 @@ static void __do_kernel_fault(unsigned long addr, unsigned int esr,
  */
 static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
                             unsigned int esr, unsigned int sig, int code,
-                            struct pt_regs *regs)
+                            struct pt_regs *regs, int fault)
 {
         struct siginfo si;
         const struct fault_info *inf;
+        unsigned int lsb = 0;
 
         if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) {
                 inf = esr_to_fault_info(esr);
@@ -277,6 +279,17 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
         si.si_errno = 0;
         si.si_code = code;
         si.si_addr = (void __user *)addr;
+        /*
+         * Either small page or large page may be poisoned.
+         * In other words, VM_FAULT_HWPOISON_LARGE and
+         * VM_FAULT_HWPOISON are mutually exclusive.
+         */
+        if (fault & VM_FAULT_HWPOISON_LARGE)
+                lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
+        else if (fault & VM_FAULT_HWPOISON)
+                lsb = PAGE_SHIFT;
+        si.si_addr_lsb = lsb;
+
         force_sig_info(sig, &si, tsk);
 }
 
@@ -291,7 +304,7 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re
          */
         if (user_mode(regs)) {
                 inf = esr_to_fault_info(esr);
-                __do_user_fault(tsk, addr, esr, inf->sig, inf->code, regs);
+                __do_user_fault(tsk, addr, esr, inf->sig, inf->code, regs, 0);
         } else
                 __do_kernel_fault(addr, esr, regs);
 }
@@ -478,6 +491,9 @@ retry:
                  */
                 sig = SIGBUS;
                 code = BUS_ADRERR;
+        } else if (fault & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) {
+                sig = SIGBUS;
+                code = BUS_MCEERR_AR;
         } else {
                 /*
                  * Something tried to access memory that isn't in our memory
@@ -488,7 +504,7 @@ retry:
                         SEGV_ACCERR : SEGV_MAPERR;
         }
 
-        __do_user_fault(tsk, addr, esr, sig, code, regs);
+        __do_user_fault(tsk, addr, esr, sig, code, regs, fault);
         return 0;
 
 no_context: