On Fri, 19 Nov 2021 14:07:09 +0000, Sai Prakash Ranjan <quic_saipraka@xxxxxxxxxxx> wrote: > > On 11/19/2021 7:13 PM, Marc Zyngier wrote: > > On Mon, 15 Nov 2021 11:33:29 +0000, > > Sai Prakash Ranjan <quic_saipraka@xxxxxxxxxxx> wrote: > >> From: Prasad Sodagudi <psodagud@xxxxxxxxxxxxxx> > >> [...] > >> Reason why we wouldn't need value along with mmio write log is > >> that value can be easily deduced from the caller_name+offset which is > >> printed already by the rwmmio trace events which gives the exact > >> location of mmio writes and the value is easily known from the driver. > > That's a very narrow view of what can be written in an MMIO > > registers. We write dynamic values at all times, and if we are able to > > trace MMIO writes, then the value written out must be part of the trace. > > > > I'd rather you try and get to the bottom of this issue rather than > > paper over it. > > > > Thanks, > > > > M. > > > > Sure, idea was to put it out in the open if anyone has any idea as > to what might be happening there since the version where directly > instrumenting the raw read/write accessors in arm64/asm/io.h was > working fine casting doubts if this has to do something with > inlining as Arnd mentioned before. Yup. I wouldn't be surprised if MMIO accessors were getting directly inlined at the wrong location and creating havoc. For example: writel(readl(addr1) | 1, addr2); If you're not careful about capturing the result of the read rather than the read itself, you can end-up with something really funky. No idea if that's what is happening, but a disassembly of the generated code could tell you. M. -- Without deviation from the norm, progress is not possible.
