On Fri, Sep 5, 2025, at 10:16, Anders Roxell wrote:
On Fri, 5 Sept 2025 at 07:28, Kees Cook kees@kernel.org wrote:
@@ -5949,7 +5950,10 @@ int pcie_set_readrq(struct pci_dev *dev, int rq) rq = mps; }
v = FIELD_PREP(PCI_EXP_DEVCTL_READRQ, ffs(rq) - 8);
firstbit = ffs(rq);if (firstbit < 8)return -EINVAL;v = FIELD_PREP(PCI_EXP_DEVCTL_READRQ, firstbit - 8);Hi Kees,
Thank you for looking into this.
These warnings are not a one time thing. the later versions of gcc can figure it out that firstbit is at least 8 based on the "rq < 128" (i guess), so we're adding bogus code. maybe we should just disable the check for gcc-8.
Out of the three failures I saw, two also happened with gcc-9, but gcc-10 looks clean so far.
\
(0 + (_val)) : 0, \ _pfx "value too large for the field"); \ BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \ __bf_cast_unsigned(_reg, ~0ull), \I found similar patterns with ffs and FIELD_PREP here drivers/dma/uniphier-xdmac.c row 156 and 165 drivers/gpu/drm/i915/display/intel_cursor_regs.h row 17
I did not come across build failures for these.
Arnd