kernel/linux.git/arch/arc/include/asm/dsp-impl.h, branch v6.12.80

ARC: guard dsp early init against non ARCv2

2020-04-29T18:53:51+00:00

As of today we guard early DSP init code with ARC_AUX_DSP_BUILD (0x7A) BCR check to verify that we have CPU with DSP configured. However that's not enough as in ARCv1 CPU the same BCR (0x7A) is used for checking MUL/MAC instructions presence. So, let's guard DSP early init against non ARCv2. Fixes: 4827d0cf744e ("ARC: handle DSP presence in HW") Reported-by: Angelo Ribeiro Suggested-by: Jose Abreu Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta

ARC: allow userspace DSP applications to use AGU extensions

2020-03-16T17:30:49+00:00

To be able to run DSP-enabled userspace applications with AGU (address generation unit) extensions we additionally need to save and restore following registers at context switch: * AGU_AP* * AGU_OS* * AGU_MOD* Reviewed-by: Vineet Gupta Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta

ARC: add support for DSP-enabled userspace applications

2020-03-16T17:30:49+00:00

To be able to run DSP-enabled userspace applications we need to save and restore following DSP-related registers: At IRQ/exception entry/exit: * DSP_CTRL (save it and reset to value suitable for kernel) * ACC0_LO, ACC0_HI (we already save them as r58, r59 pair) At context switch: * ACC0_GLO, ACC0_GHI * DSP_BFLY0, DSP_FFT_CTRL Reviewed-by: Vineet Gupta Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta

ARC: handle DSP presence in HW

2020-03-16T17:23:44+00:00

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 Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta