Messages in this thread | | | From | Anup Patel <> | Date | Mon, 19 Aug 2019 10:19:01 +0530 | Subject | Re: [PATCH] RISC-V: Fix FIXMAP area corruption on RV32 systems |
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On Sun, Aug 18, 2019 at 11:49 PM Christoph Hellwig <hch@infradead.org> wrote: > > > +#define FIXADDR_TOP (VMALLOC_START) > > Nit: no need for the braces, the definitions below don't use it > either.
Sure, I will update and send v2 soon.
> > > +#ifdef CONFIG_64BIT > > +#define FIXADDR_SIZE PMD_SIZE > > +#else > > +#define FIXADDR_SIZE PGDIR_SIZE > > +#endif > > +#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) > > + > > /* > > - * Task size is 0x4000000000 for RV64 or 0xb800000 for RV32. > > + * Task size is 0x4000000000 for RV64 or 0x9fc00000 for RV32. > > * Note that PGDIR_SIZE must evenly divide TASK_SIZE. > > */ > > #ifdef CONFIG_64BIT > > #define TASK_SIZE (PGDIR_SIZE * PTRS_PER_PGD / 2) > > #else > > -#define TASK_SIZE VMALLOC_START > > +#define TASK_SIZE FIXADDR_START > > #endif > > Mentioning the addresses is a little weird. IMHO this would be > a much nicer place to explain the high-level memory layout, including > maybe a little ASCII art. Also we could have one #ifdef CONFIG_64BIT > for both related values. Last but not least instead of saying that > something should be dividable it would be nice to have a BUILD_BUG_ON > to enforce it. > > Either way we are late in the cycle, so I guess this is ok for now: > > Reviewed-by: Christoph Hellwig <hch@lst.de> > > But I'd love to see this area improved a little further as it is full > of mine fields.
I agree with you. We also have Sparsemem and KASAN patches which touch virtual memory layout so it's important to have virtual memory layout documented clearly. I can add the required documentation as separate patch.
I think the best place to add ASCII art would be asm/pgtable.h where all virtual memory related defines are placed. Suggestions??
Regards, Anup
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