On Jun 08 2018, Palmer Dabbelt <[email protected]> wrote: > On Thu, 07 Jun 2018 03:27:27 PDT (-0700), [email protected] wrote: >> With CONFIG_MODVERSIONS=y the R_RISCV_32 relocation is used by the >> __kcrctab section. >> >> Signed-off-by: Andreas Schwab <[email protected]> >> --- >> arch/riscv/kernel/module.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c >> index 5dddba301d..1d5e9b934b 100644 >> --- a/arch/riscv/kernel/module.c >> +++ b/arch/riscv/kernel/module.c >> @@ -17,6 +17,17 @@ >> #include <linux/errno.h> >> #include <linux/moduleloader.h> >> >> +static int apply_r_riscv_32_rela(struct module *me, u32 *location, Elf_Addr >> v) >> +{ >> + if (v != (u32)v) { > > My worry with this kind of check is that it relies on some sort of > undefined behavior in C and that at some point in the future GCC will just > go decide the check can never fail. I checked and GCC doesn't elide these > checks now, so I might be wrong. > > Is this defined to do what it looks like it's doing?
This is unsigned arithmetic, thus fully defined. Andreas. -- Andreas Schwab, SUSE Labs, [email protected] GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different."
