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| 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/Kconfig | |
| parent | 240c84b1c22c9912ed1c8a96251b44e85d2ca2ed (diff) | |
| download | linux-4827d0cf744e7e9cc73f10e1f4eaca904a3868c1.tar.bz2 | |
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/Kconfig')
| -rw-r--r-- | arch/arc/Kconfig | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig index 7124ab82dfa3..55432a8fc20d 100644 --- a/arch/arc/Kconfig +++ b/arch/arc/Kconfig @@ -401,13 +401,40 @@ config ARC_HAS_DIV_REM default y config ARC_HAS_ACCL_REGS - bool "Reg Pair ACCL:ACCH (FPU and/or MPY > 6)" + bool "Reg Pair ACCL:ACCH (FPU and/or MPY > 6 and/or DSP)" default y help Depending on the configuration, CPU can contain accumulator reg-pair (also referred to as r58:r59). These can also be used by gcc as GPR so kernel needs to save/restore per process +config ARC_DSP_HANDLED + def_bool n + +choice + prompt "DSP support" + default ARC_DSP_NONE + help + Depending on the configuration, CPU can contain DSP registers + (ACC0_GLO, ACC0_GHI, DSP_BFLY0, DSP_CTRL, DSP_FFT_CTRL). + Bellow is options describing how to handle these registers in + interrupt entry / exit and in context switch. + +config ARC_DSP_NONE + bool "No DSP extension presence in HW" + help + No DSP extension presence in HW + +config ARC_DSP_KERNEL + bool "DSP extension in HW, no support for userspace" + select ARC_HAS_ACCL_REGS + select ARC_DSP_HANDLED + help + DSP extension presence in HW, no support for DSP-enabled userspace + applications. We don't save / restore DSP registers and only do + some minimal preparations so userspace won't be able to break kernel +endchoice + config ARC_IRQ_NO_AUTOSAVE bool "Disable hardware autosave regfile on interrupts" default n |