NPTL, round one.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 43 insertions, 3 deletions

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 94d9141c04c1..15fed0202154 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -360,6 +360,10 @@ static inline int get_insn_opcode(struct pt_regs *regs, unsigned int *opcode)
 #define OFFSET 0x0000ffff
 #define LL     0xc0000000
 #define SC     0xe0000000
+#define SPEC3  0x7c000000
+#define RD     0x0000f800
+#define FUNC   0x0000003f
+#define RDHWR  0x0000003b
 
 /*
  * The ll_bit is cleared by r*_switch.S
@@ -495,6 +499,37 @@ static inline int simulate_llsc(struct pt_regs *regs)
         return -EFAULT;                 /* Strange things going on ... */
 }
 
+/*
+ * Simulate trapping 'rdhwr' instructions to provide user accessible
+ * registers not implemented in hardware.  The only current use of this
+ * is the thread area pointer.
+ */
+static inline int simulate_rdhwr(struct pt_regs *regs)
+{
+        struct thread_info *ti = current->thread_info;
+        unsigned int opcode;
+
+        if (unlikely(get_insn_opcode(regs, &opcode)))
+                return -EFAULT;
+
+        if (unlikely(compute_return_epc(regs)))
+                return -EFAULT;
+
+        if ((opcode & OPCODE) == SPEC3 && (opcode & FUNC) == RDHWR) {
+                int rd = (opcode & RD) >> 11;
+                int rt = (opcode & RT) >> 16;
+                switch (rd) {
+                        case 29:
+                                regs->regs[rt] = ti->tp_value;
+                                break;
+                        default:
+                                return -EFAULT;
+                }
+        }
+
+        return 0;
+}
+
 asmlinkage void do_ov(struct pt_regs *regs)
 {
         siginfo_t info;
@@ -641,6 +676,9 @@ asmlinkage void do_ri(struct pt_regs *regs)
                 if (!simulate_llsc(regs))
                         return;
 
+        if (!simulate_rdhwr(regs))
+                return;
+
         force_sig(SIGILL, current);
 }
 
@@ -654,11 +692,13 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 
         switch (cpid) {
         case 0:
-                if (cpu_has_llsc)
-                        break;
+                if (!cpu_has_llsc)
+                        if (!simulate_llsc(regs))
+                                return;
 
-                if (!simulate_llsc(regs))
+                if (!simulate_rdhwr(regs))
                         return;
+
                 break;
 
         case 1: