sparc64: Implement perf_arch_fetch_caller_regs

We provide regs->tstate, regs->tpc, regs->tnpc and
regs->u_regs[UREG_FP].

regs->tstate is necessary for:

	user_mode()		(via perf_exclude_event())

	perf_misc_flags()	(via perf_prepare_sample())

regs->tpc is necessary for:

	perf_instruction_pointer() (via perf_prepare_sample())

and regs->u_regs[UREG_FP] is necessary for:

	perf_callchain()	(via perf_prepare_sample())

The regs->tnpc value is provided just to be tidy.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 75 insertions, 0 deletions

diff --git a/arch/sparc/kernel/helpers.S b/arch/sparc/kernel/helpers.S
index 314dd0c9fc5b..92090cc9e829 100644
--- a/arch/sparc/kernel/helpers.S
+++ b/arch/sparc/kernel/helpers.S
@@ -46,6 +46,81 @@ stack_trace_flush:
          nop
         .size           stack_trace_flush,.-stack_trace_flush
 
+#ifdef CONFIG_PERF_EVENTS
+        .globl          perf_arch_fetch_caller_regs
+        .type           perf_arch_fetch_caller_regs,#function
+perf_arch_fetch_caller_regs:
+        /* We always read the %pstate into %o5 since we will use
+         * that to construct a fake %tstate to store into the regs.
+         */
+        rdpr            %pstate, %o5
+        brz,pn          %o2, 50f
+         mov            %o2, %g7
+
+        /* Turn off interrupts while we walk around the register
+         * window by hand.
+         */
+        wrpr            %o5, PSTATE_IE, %pstate
+
+        /* The %canrestore tells us how many register windows are
+         * still live in the chip above us, past that we have to
+         * walk the frame as saved on the stack.   We stash away
+         * the %cwp in %g1 so we can return back to the original
+         * register window.
+         */
+        rdpr            %cwp, %g1
+        rdpr            %canrestore, %g2
+        sub             %g1, 1, %g3
+
+        /* We have the skip count in %g7, if it hits zero then
+         * %fp/%i7 are the registers we need.  Otherwise if our
+         * %canrestore count maintained in %g2 hits zero we have
+         * to start traversing the stack.
+         */
+10:     brz,pn          %g2, 4f
+         sub            %g2, 1, %g2
+        wrpr            %g3, %cwp
+        subcc           %g7, 1, %g7
+        bne,pt          %xcc, 10b
+         sub            %g3, 1, %g3
+
+        /* We found the values we need in the cpu's register
+         * windows.
+         */
+        mov             %fp, %g3
+        ba,pt           %xcc, 3f
+         mov            %i7, %g2
+
+50:     mov             %fp, %g3
+        ba,pt           %xcc, 2f
+         mov            %i7, %g2
+
+        /* We hit the end of the valid register windows in the
+         * cpu, start traversing the stack frame.
+         */
+4:      mov             %fp, %g3
+
+20:     ldx             [%g3 + STACK_BIAS + RW_V9_I7], %g2
+        subcc           %g7, 1, %g7
+        bne,pn          %xcc, 20b
+         ldx            [%g3 + STACK_BIAS + RW_V9_I6], %g3
+
+        /* Restore the current register window position and
+         * re-enable interrupts.
+         */
+3:      wrpr            %g1, %cwp
+        wrpr            %o5, %pstate
+
+2:      stx             %g3, [%o0 + PT_V9_FP]
+        sllx            %o5, 8, %o5
+        stx             %o5, [%o0 + PT_V9_TSTATE]
+        stx             %g2, [%o0 + PT_V9_TPC]
+        add             %g2, 4, %g2
+        retl
+         stx            %g2, [%o0 + PT_V9_TNPC]
+        .size           perf_arch_fetch_caller_regs,.-perf_arch_fetch_caller_regs
+#endif /* CONFIG_PERF_EVENTS */
+
 #ifdef CONFIG_SMP
         .globl          hard_smp_processor_id
         .type           hard_smp_processor_id,#function