diff options
| author | Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> | 2020-03-05 23:02:50 +0300 |
|---|---|---|
| committer | Vineet Gupta <vgupta@synopsys.com> | 2020-03-16 10:23:44 -0700 |
| commit | 4827d0cf744e7e9cc73f10e1f4eaca904a3868c1 (patch) | |
| tree | 2b7f88fe8cb98dcba5aaffebf23bd07570ce6e27 /arch/arc/kernel | |
| parent | 240c84b1c22c9912ed1c8a96251b44e85d2ca2ed (diff) | |
ARC: handle DSP presence in HW
When DSP extensions are present, some of the regular integer instructions
such as DIV, MACD etc are executed in the DSP unit with semantics alterable
by flags in DSP_CTRL aux register. This register is writable by userspace
and thus can potentially affect corresponding instructions in kernel code,
intentionally or otherwise. So safegaurd kernel by effectively disabling
DSP_CTRL upon bootup and every entry to kernel.
Do note that for this config we simply zero out the DSP_CTRL reg assuming
userspace doesn't really care about DSP. The next patch caters to the DSP
aware userspace where this reg is saved/restored upon kernel entry/exit.
Reviewed-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'arch/arc/kernel')
| -rw-r--r-- | arch/arc/kernel/head.S | 4 | ||||
| -rw-r--r-- | arch/arc/kernel/setup.c | 3 |
2 files changed, 7 insertions, 0 deletions
diff --git a/arch/arc/kernel/head.S b/arch/arc/kernel/head.S index 6f41265f6250..6eb23f1545ee 100644 --- a/arch/arc/kernel/head.S +++ b/arch/arc/kernel/head.S @@ -14,6 +14,7 @@ #include <asm/entry.h> #include <asm/arcregs.h> #include <asm/cache.h> +#include <asm/dsp-impl.h> #include <asm/irqflags.h> .macro CPU_EARLY_SETUP @@ -59,6 +60,9 @@ #endif kflag r5 #endif + ; Config DSP_CTRL properly, so kernel may use integer multiply, + ; multiply-accumulate, and divide operations + DSP_EARLY_INIT .endm .section .init.text, "ax",@progbits diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c index 820c0cfb0702..1ed1528d9045 100644 --- a/arch/arc/kernel/setup.c +++ b/arch/arc/kernel/setup.c @@ -27,6 +27,7 @@ #include <asm/unwind.h> #include <asm/mach_desc.h> #include <asm/smp.h> +#include <asm/dsp-impl.h> #define FIX_PTR(x) __asm__ __volatile__(";" : "+r"(x)) @@ -440,6 +441,8 @@ static void arc_chk_core_config(void) /* Accumulator Low:High pair (r58:59) present if DSP MPY or FPU */ present = cpu->extn_mpy.dsp | cpu->extn.fpu_sp | cpu->extn.fpu_dp; CHK_OPT_STRICT(CONFIG_ARC_HAS_ACCL_REGS, present); + + dsp_config_check(); } } |