From 9e196938aa1c0517f81139bda0f2f26e0347c64e Mon Sep 17 00:00:00 2001 From: Aaron Larson Date: Fri, 24 Jun 2016 13:18:28 -0700 Subject: [PATCH] target-ppc: gen_pause for instructions: yield, mdoio, mdoom, miso Call gen_pause for all "or rx,rx,rx" encodings other nop. This provides a reasonable implementation for yield, and a better approximation for mdoio, mdoom, and miso. The choice to pause for all encodings !=0 leverages the PowerISA admonition that the reserved encodings might change program priority, providing a slight "future proofing". Signed-off-by: Aaron Larson Acked-by: Benjamin Herrenschmidt Signed-off-by: David Gibson --- target-ppc/translate.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/target-ppc/translate.c b/target-ppc/translate.c index 49fe761407..92030b66a5 100644 --- a/target-ppc/translate.c +++ b/target-ppc/translate.c @@ -1471,7 +1471,7 @@ static void gen_or(DisasContext *ctx) } else if (unlikely(Rc(ctx->opcode) != 0)) { gen_set_Rc0(ctx, cpu_gpr[rs]); #if defined(TARGET_PPC64) - } else { + } else if (rs != 0) { /* 0 is nop */ int prio = 0; switch (rs) { @@ -1514,7 +1514,6 @@ static void gen_or(DisasContext *ctx) break; #endif default: - /* nop */ break; } if (prio) { @@ -1524,13 +1523,15 @@ static void gen_or(DisasContext *ctx) tcg_gen_ori_tl(t0, t0, ((uint64_t)prio) << 50); gen_store_spr(SPR_PPR, t0); tcg_temp_free(t0); - /* Pause us out of TCG otherwise spin loops with smt_low - * eat too much CPU and the kernel hangs - */ -#if !defined(CONFIG_USER_ONLY) - gen_pause(ctx); -#endif } +#if !defined(CONFIG_USER_ONLY) + /* Pause out of TCG otherwise spin loops with smt_low eat too much + * CPU and the kernel hangs. This applies to all encodings other + * than no-op, e.g., miso(rs=26), yield(27), mdoio(29), mdoom(30), + * and all currently undefined. + */ + gen_pause(ctx); +#endif #endif } }