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ARCv2: don't assume core 0x54 has dual issue

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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>
This commit is contained in:
Vineet Gupta 2019-02-21 13:44:49 -08:00 committed by Greg Kroah-Hartman
parent 3220aa9b00
commit 8b9187e7df
2 changed files with 29 additions and 5 deletions
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8
arch/arc/include/asm/arcregs.h
View file

@ -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;

26
arch/arc/kernel/setup.c
View file

@ -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);
}
}
}