From 7b2e932f633bcb7b190fc7031ce6dac75f8c3472 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Thu, 21 Feb 2019 13:44:49 -0800 Subject: ARCv2: don't assume core 0x54 has dual issue The first release of core4 (0x54) was dual issue only (HS4x). Newer releases allow hardware to be configured as single issue (HS3x) or dual issue. Prevent accessing a HS4x only aux register in HS3x, which otherwise leads to illegal instruction exceptions Signed-off-by: Vineet Gupta --- arch/arc/include/asm/arcregs.h | 8 ++++++++ arch/arc/kernel/setup.c | 26 +++++++++++++++++++++----- 2 files changed, 29 insertions(+), 5 deletions(-) (limited to 'arch/arc') diff --git a/arch/arc/include/asm/arcregs.h b/arch/arc/include/asm/arcregs.h index f1b86cef09057..a27eafdc82602 100644 --- a/arch/arc/include/asm/arcregs.h +++ b/arch/arc/include/asm/arcregs.h @@ -151,6 +151,14 @@ struct bcr_isa_arcv2 { #endif }; +struct bcr_uarch_build_arcv2 { +#ifdef CONFIG_CPU_BIG_ENDIAN + unsigned int pad:8, prod:8, maj:8, min:8; +#else + unsigned int min:8, maj:8, prod:8, pad:8; +#endif +}; + struct bcr_mpy { #ifdef CONFIG_CPU_BIG_ENDIAN unsigned int pad:8, x1616:8, dsp:4, cycles:2, type:2, ver:8; diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c index 93d4d66398737..7b2340996cf80 100644 --- a/arch/arc/kernel/setup.c +++ b/arch/arc/kernel/setup.c @@ -199,13 +199,29 @@ static void read_arc_build_cfg_regs(void) cpu->bpu.ret_stk = 4 << bpu.rse; if (cpu->core.family >= 0x54) { - unsigned int exec_ctrl; - READ_BCR(AUX_EXEC_CTRL, exec_ctrl); - cpu->extn.dual_enb = !(exec_ctrl & 1); + struct bcr_uarch_build_arcv2 uarch; - /* dual issue always present for this core */ - cpu->extn.dual = 1; + /* + * The first 0x54 core (uarch maj:min 0:1 or 0:2) was + * dual issue only (HS4x). But next uarch rev (1:0) + * allows it be configured for single issue (HS3x) + * Ensure we fiddle with dual issue only on HS4x + */ + READ_BCR(ARC_REG_MICRO_ARCH_BCR, uarch); + + if (uarch.prod == 4) { + unsigned int exec_ctrl; + + /* dual issue hardware always present */ + cpu->extn.dual = 1; + + READ_BCR(AUX_EXEC_CTRL, exec_ctrl); + + /* dual issue hardware enabled ? */ + cpu->extn.dual_enb = !(exec_ctrl & 1); + + } } } -- cgit v1.2.3