4.19-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 7b2e932f633bcb7b190fc7031ce6dac75f8c3472 ]
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 vgupta@synopsys.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arc/include/asm/arcregs.h | 8 ++++++++ arch/arc/kernel/setup.c | 26 +++++++++++++++++++++----- 2 files changed, 29 insertions(+), 5 deletions(-)
diff --git a/arch/arc/include/asm/arcregs.h b/arch/arc/include/asm/arcregs.h index 49bfbd879caa..bdbdaef902eb 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 62a30e58441c..3320ca2fe20f 100644 --- a/arch/arc/kernel/setup.c +++ b/arch/arc/kernel/setup.c @@ -196,13 +196,29 @@ static void read_arc_build_cfg_regs(void) cpu->bpu.num_pred = 2048 << bpu.pte;
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); + + } } }