On Mon, Aug 03, 2009 at 12:33:25PM -0700, David Daney wrote: > Ralf Baechle wrote: >> On Thu, Jul 30, 2009 at 11:49:23AM -0700, David VomLehn wrote: >> >>> To: GCC Help Mailing List <gcc-help@xxxxxxxxxxx>, >>> Linux MIPS Mailing List <linux-mips@xxxxxxxxxxxxxx> >>> Subject: Relocation problem with MIPS kernel modules >>> Content-Type: text/plain; charset=us-ascii >>> >>> I have a MIPS loadable kernel module that, when I try to insmod it, causes the >>> kernel to emit the message: >>> >>> module xyz: dangerous relocation ... >> >> The GNU tools as an extension over the MIPS ABI allows an arbitrary number of >> R_MIPS_HI16 relocations to be followed by a R_MIPS_LO16 symbol. All >> relocations of this sequence must use the same symbol, of course. This is >> a very old extension; I think it predates the Linux/MIPS port. >> > > Actually I think it is the opposite: > > RELOCATION RECORDS FOR [.text]: > OFFSET TYPE VALUE > 00000000 R_MIPS_HI16 .bss+0x00000004 > 00000008 R_MIPS_LO16 .bss+0x00000004 > 00000014 R_MIPS_LO16 .bss+0x00000004 > > We load the hi16 value into a register and then use multiple lo16 > offsets for the follow loads and stores to the same location. On a > read-modify-write we only want to load the base address one time. This particular case is covered by the old MIPS Processor psABI: R_MIPS_LO16 entries without an R_MIPS_HI16 entry immediately preceding are orphaned and the previously defined R_MIPS_HI16 is used for computing the addend. The code in module.c looks like it implements the extension to which Ralf refers. > David Daney David VomLehn
