ARCv2: entry: save Accumulator register pair (r58:59) if present

Accumulator is present in configs with FPU and/or DSP MPY (mpy > 6)

Instead of doing this in pt_regs (and thus every kernel entry/exit),
this could have been done in context switch (and for user task only) as
currently kernel doesn't clobber these registers for its own accord.
However we will soon start using 64-bit multiply instructions for kernel
which can clobber these. Also gcc folks also plan to start using these
as GPRs, hence better to always save/restore them

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h
index 47111d565a95..5297faa8a378 100644
--- a/arch/arc/include/asm/ptrace.h
+++ b/arch/arc/include/asm/ptrace.h
@@ -86,6 +86,10 @@ struct pt_regs {
 
 	unsigned long r12, r30;
 
+#ifdef CONFIG_ARC_HAS_ACCL_REGS
+	unsigned long r58, r59;	/* ACCL/ACCH used by FPU / DSP MPY */
+#endif
+
 	/*------- Below list auto saved by h/w -----------*/
 	unsigned long r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11;