Messages in this thread | | | From | Nick Desaulniers <> | Date | Fri, 10 Sep 2021 17:16:29 -0700 | Subject | Re: [PATCH 01/10] Documentation: raise minimum supported version of GCC to 5.1 |
| |
On Fri, Sep 10, 2021 at 4:56 PM Nathan Chancellor <nathan@kernel.org> wrote: > > On 9/10/2021 4:40 PM, Nick Desaulniers wrote: > > commit fad7cd3310db ("nbd: add the check to prevent overflow in > > __nbd_ioctl()") > > > > raised an issue from the fallback helpers added in > > > > commit f0907827a8a9 ("compiler.h: enable builtin overflow checkers and add fallback code") > > > > Specifically, the helpers for checking whether the results of a > > multiplication overflowed (__unsigned_mul_overflow, > > __signed_add_overflow) use the division operator when > > !COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW. This is problematic for 64b > > operands on 32b hosts. > > "hosts" -> "targets" or "architectures"?
Yes, will revise to "targets."
> > It might be worth putting the error that Stephen found here?
Doh! Yes, in v2, I'll include the following additional context: ``` The following error is observed when building for 32b powerpc: > ERROR: modpost: "__divdi3" [drivers/block/nbd.ko] undefined!
As Stephen Rothwell notes: > The added check_mul_overflow() call is being passed 64 bit values. > COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW is not set for this build (see > include/linux/overflow.h). ```
> > > Also, because the macro is type agnostic, it is very difficult to write > > a similarly type generic macro that dispatches to one of: > > * div64_s64 > > * div64_u64 > > * div_s64 > > * div_u64 > > > > Raising the minimum supported versions allows us to remove all of the > > fallback helpers for !COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW, instead > > dispatching the compiler builtins. > > > > arm64 has already raised the minimum supported GCC version to 5.1, do > > this for all targets now. See the link below for the previous > > discussion. > > > > Link: https://lore.kernel.org/all/20210909182525.372ee687@canb.auug.org.au/ > > Link: https://lore.kernel.org/lkml/CAK7LNASs6dvU6D3jL2GG3jW58fXfaj6VNOe55NJnTB8UPuk2pA@mail.gmail.com/ > > Link: https://github.com/ClangBuiltLinux/linux/issues/1438 > > Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> > > Reported-by: Nathan Chancellor <nathan@kernel.org> > > Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> > > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> > > Reviewed-by: Nathan Chancellor <nathan@kernel.org> > > > --- > > Documentation/process/changes.rst | 2 +- > > scripts/min-tool-version.sh | 8 +------- > > 2 files changed, 2 insertions(+), 8 deletions(-) > > > > diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst > > index d3a8557b66a1..e35ab74a0f80 100644 > > --- a/Documentation/process/changes.rst > > +++ b/Documentation/process/changes.rst > > @@ -29,7 +29,7 @@ you probably needn't concern yourself with pcmciautils. > > ====================== =============== ======================================== > > Program Minimal version Command to check the version > > ====================== =============== ======================================== > > -GNU C 4.9 gcc --version > > +GNU C 5.1 gcc --version > > Clang/LLVM (optional) 10.0.1 clang --version > > GNU make 3.81 make --version > > binutils 2.23 ld -v > > diff --git a/scripts/min-tool-version.sh b/scripts/min-tool-version.sh > > index 319f92104f56..4edc708baa63 100755 > > --- a/scripts/min-tool-version.sh > > +++ b/scripts/min-tool-version.sh > > @@ -17,13 +17,7 @@ binutils) > > echo 2.23.0 > > ;; > > gcc) > > - # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293 > > - # https://lore.kernel.org/r/20210107111841.GN1551@shell.armlinux.org.uk > > - if [ "$SRCARCH" = arm64 ]; then > > - echo 5.1.0 > > - else > > - echo 4.9.0 > > - fi > > + echo 5.1.0 > > ;; > > icc) > > # temporary > >
-- Thanks, ~Nick Desaulniers
| |