On 1/13/21 5:16 PM, Catalin Marinas wrote: > On Thu, Jan 07, 2021 at 05:29:05PM +0000, Vincenzo Frascino wrote: >> Architectures supported by KASAN HW can provide a light mode of >> execution. On an MTE enabled arm64 hw for example this can be identified >> with the asynch mode of execution. If an async exception occurs, the >> arm64 core updates a register which is asynchronously detected the next >> time in which the kernel is accessed. > > What do you mean by "the kernel is accessed"? Also, there is no > "exception" as such, only a bit in a register updated asynchronously. So > the last sentence could be something like: > > In this mode, if a tag check fault occurs, the TFSR_EL1 register is > updated asynchronously. The kernel checks the corresponding bits > periodically. > > (or you can be more precise on when the kernel checks for such faults) >
Yes, I agree, I will change it accordingly. What I wrote has a similar meaning but your exposition is more clear. >> KASAN requires a specific mode of execution to make use of this hw feature. >> >> Add KASAN HW light execution mode. > > Shall we call it "fast"? ;) > >> --- /dev/null >> +++ b/include/linux/kasan_def.h >> @@ -0,0 +1,25 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +#ifndef _LINUX_KASAN_DEF_H >> +#define _LINUX_KASAN_DEF_H >> + >> +enum kasan_arg_mode { >> + KASAN_ARG_MODE_DEFAULT, >> + KASAN_ARG_MODE_OFF, >> + KASAN_ARG_MODE_LIGHT, >> + KASAN_ARG_MODE_PROD, >> + KASAN_ARG_MODE_FULL, >> +}; >> + >> +enum kasan_arg_stacktrace { >> + KASAN_ARG_STACKTRACE_DEFAULT, >> + KASAN_ARG_STACKTRACE_OFF, >> + KASAN_ARG_STACKTRACE_ON, >> +}; >> + >> +enum kasan_arg_fault { >> + KASAN_ARG_FAULT_DEFAULT, >> + KASAN_ARG_FAULT_REPORT, >> + KASAN_ARG_FAULT_PANIC, >> +}; >> + >> +#endif /* _LINUX_KASAN_DEF_H */ > > I thought we agreed not to expose the KASAN internal but come up with > another abstraction. Maybe this was after you posted these patches. > Yes, indeed we agreed and I am going to change it in v3. The agreement temporally came after I posted v2 hence it is not reflected here. -- Regards, Vincenzo