On Mon, Jan 31, 2022 at 02:30:32PM +0100, Arnd Bergmann wrote: > On Sun, Jan 30, 2022 at 6:53 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > > Thanks for doing the sweep, Mike. > > > > I think I found a deeper problem which is masked due to our maze of > > header files: > > > > include/asm-generic/io.h:#ifndef virt_to_phys > > include/asm-generic/io.h:#define virt_to_phys virt_to_phys > > > > so there's an assumption that <asm/io.h> defines virt_to_phys(). > > You can see that in a number of architectures, eg: > > > > arch/alpha/include/asm/io.h:static inline unsigned long virt_to_phys(volatile void *address) > > arch/ia64/include/asm/io.h:#define virt_to_phys virt_to_phys > > arch/mips/include/asm/io.h:#define virt_to_phys virt_to_phys > > arch/nios2/include/asm/io.h:#define virt_to_phys(vaddr) \ > > arch/parisc/include/asm/io.h:#define virt_to_phys(a) ((unsigned long)__pa(a)) > > arch/powerpc/include/asm/io.h:#define virt_to_phys virt_to_phys > > arch/sh/include/asm/io.h:#define virt_to_phys(address) ((unsigned long)(address)) > > arch/x86/include/asm/io.h:#define virt_to_phys virt_to_phys > > > > That's clearly not the right place to define it. Two architectures > > put it in asm/memory.h: > > > > arch/arm/include/asm/memory.h:#define virt_to_phys virt_to_phys > > arch/arm64/include/asm/memory.h:#define virt_to_phys virt_to_phys > > > > then: > > > > arch/m68k/include/asm/virtconvert.h:#define virt_to_phys virt_to_phys > > arch/sparc/include/asm/page_32.h:#define virt_to_phys __pa > > arch/sparc/include/asm/page_64.h:#define virt_to_phys __pa > > > > This needs to be properly sorted out, but I don't want to tell Karolina > > that's now her job as a prerequisite for merging this patchset; that > > would be unfair. > > > > Cc'ing Arnd. This is the kind of awful mess that he loves fixing ;-) > > Adding Ingo as well. I'm in the middle of getting his fast-headers tree > to work well on a couple of other architectures, and the memory.h/page.h/io.h > mess is one of the tricky bits in there, both in his series and in my > follow-ups. > > What makes this bit even worse is that the architectures also not just > inconsistent about where they put __va/__pa and > virt_to_phys/phys_to_virt, they are also inconsistent about which of the > two pairs is based on the other, so any way you touch it means you > will break something, and changing it now will likely require a tricky > rebase of Ingo's patches. Hmm, whatever we'll do with these conversions, it will be tricky for Ingo's tree... > Ingo, do you happen to have patches already that could be isolated > from your series to address this? Maybe we can add the > linux/mm_page_address.h header first and require that each > architecture puts these macros into asm/page_address.h. > We need to isolate these anyway, because the page addresses > are used in a lot of places that don't need to include any of the > remaining headers (page.h, mm.h, memory.h, io.h) that pull in > hundreds more. I peeked at Ingo's tree and there is this: commit 3426911a3f83 (headers/deps: io/arch: Move the address translation APIs from <asm/io.h> to <asm/io_extra.h>) (https://git.kernel.org/pub/scm/linux/kernel/git/mingo/tip.git/commit/?id=3426911a3f833930d92f3aebe349f09a513375d9) It moves virt_to_phys and phys_to_virt on x86 to a new header. I actually liked m68k's name for a header with virt_to_phys/phys_to_virt definitions - virtconvert.h. As an experiment I pulled out address translations from arch/arm/include/memory.h to arch/arm/include/virtconvert.h, it wasn't that bad: arch/arm/include/asm/dma-mapping.h | 2 + arch/arm/include/asm/io.h | 1 + arch/arm/include/asm/memory.h | 244 ---------------------------------- arch/arm/include/asm/pgtable.h | 1 + arch/arm/include/asm/virtconvert.h | 264 +++++++++++++++++++++++++++++++++++++ arch/arm/kernel/psci_smp.c | 1 + 6 files changed, 269 insertions(+), 244 deletions(-) (https://git.kernel.org/rppt/linux/c/4c34ec16319fc85280aad89d7a74df845c1614fc) > Arnd -- Sincerely yours, Mike.
