Messages in this thread | | | Subject | Re: [PATCH] y2038: Remove newstat family from default syscall set | From | Guenter Roeck <> | Date | Thu, 6 Sep 2018 06:24:20 -0700 |
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On 09/06/2018 02:45 AM, Palmer Dabbelt wrote: > On Sat, 01 Sep 2018 10:43:53 PDT (-0700), linux@roeck-us.net wrote: >> Hi Arnd, >> >> On Fri, Apr 13, 2018 at 11:50:12AM +0200, Arnd Bergmann wrote: >>> We have four generations of stat() syscalls: >>> - the oldstat syscalls that are only used on the older architectures >>> - the newstat family that is used on all 64-bit architectures but >>> lacked support for large files on 32-bit architectures. >>> - the stat64 family that is used mostly on 32-bit architectures to >>> replace newstat >>> - statx() to replace all of the above, adding 64-bit timestamps among >>> other things. >>> >>> We already compile stat64 only on those architectures that need it, >>> but newstat is always built, including on those that don't reference >>> it. This adds a new __ARCH_WANT_NEW_STAT symbol along the lines of >>> __ARCH_WANT_OLD_STAT and __ARCH_WANT_STAT64 to control compilation of >>> newstat. All architectures that need it use an explict define, the >>> others now get a little bit smaller, and future architecture (including >>> 64-bit targets) won't ever see it. >>> >> >> This patch causes my riscv boot tests to crash in -next > > Ah, thanks for running these! > >> sbin/init: error while loading shared libraries: libc.so.6: cannot stat shared object: Error 38 >> Kernel panic - not syncing: Attempted to kill init! exitcode=0x00007f00 >> >> The following change fixes the problem for me, but of course I have no idea >> if it is correct. Copying RISC-V maintainers for input. >> >> Guenter >> >> --- >> diff --git a/arch/riscv/include/asm/unistd.h b/arch/riscv/include/asm/unistd.h >> index 0caea01d5cca..eff7aa9aa163 100644 >> --- a/arch/riscv/include/asm/unistd.h >> +++ b/arch/riscv/include/asm/unistd.h >> @@ -16,6 +16,7 @@ >> * be included multiple times. See uapi/asm/syscalls.h for more info. >> */ >> >> +#define __ARCH_WANT_NEW_STAT >> #define __ARCH_WANT_SYS_CLONE >> #include <uapi/asm/unistd.h> >> #include <uapi/asm/syscalls.h> > > I'm afraid I'm not sure what the right thing to do here is either, but from the patch description it does seem like we should have this guarded by an "#ifdef CONFIG_32BIT" so we can keep it out of our 32-bit ABI (which isn't in glibc yet, so isn't stable) in favor of statx() (or maybe stat64()?). The one problem here is that I can't find "newstat" anywhere in glibc to verify it's actually supposed to be part of our 64-bit ABI, though I can find a bunch of references to "statx" that seem to indicate it's meant to be present. > > That said, assuming you don't have anything wacky going on in userspace if this breaks the ABI then it breaks the ABI, so however newstat got into a binary we still need to keep it around. Poking around my Fedora glibc image I see >
userspace is a root file system built with buildroot (modified to support riscv64), using glibc 2.26. Nothing wacky, sorry.
Guenter
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