Messages in this thread | | | Date | Wed, 12 Apr 2017 12:03:08 +0200 | From | Borislav Petkov <> | Subject | Re: [v6 PATCH 04/21] x86/mpx, x86/insn: Relocate insn util functions to a new insn-kernel |
| |
On Tue, Mar 07, 2017 at 04:32:37PM -0800, Ricardo Neri wrote: > Other kernel submodules can benefit from using the utility functions > defined in mpx.c to obtain the addresses and values of operands contained > in the general purpose registers. An instance of this is the emulation code > used for instructions protected by the Intel User-Mode Instruction > Prevention feature. > > Thus, these functions are relocated to a new insn-eval.c file. The reason > to not relocate these utilities into insn.c is that the latter solely > analyses instructions given by a struct insn without any knowledge of the > meaning of the values of instruction operands. This new utility insn- > eval.c aims to be used to resolve effective and userspace linear addresses > based on the contents of the instruction operands as well as the contents > of pt_regs structure. > > These utilities come with a separate header. This is to avoid taking insn.c > out of sync from the instructions decoders under tools/obj and tools/perf. > This also avoids adding cumbersome #ifdef's for the #include'd files > required to decode instructions in a kernel context. > > Functions are simply relocated. There are not functional or indentation > changes.
...
> + case REG_TYPE_BASE: > + regno = X86_SIB_BASE(insn->sib.value); > + /* > + * If mod is 0 and register R/EBP (regno=5) is indicated in the > + * base part of the SIB byte, the value of such register should > + * not be used in the address computation. Also, a 32-bit > + * displacement is expected in this case; the instruction > + * decoder takes care of it. This is true for both R13 and > + * R/EBP as REX.B will not be decoded. > + */ > + if (regno == 5 && X86_MODRM_MOD(insn->modrm.value) == 0) > + return -EDOM; > + > + if (X86_REX_B(insn->rex_prefix.value)) > + regno += 8; > + break; > + > + default: > + pr_err("invalid register type"); > + BUG();
WARNING: Avoid crashing the kernel - try using WARN_ON & recovery code rather than BUG() or BUG_ON() #211: FILE: arch/x86/lib/insn-eval.c:90: + BUG();
And checkpatch is kinda right. We need to warn here, not explode. Oh and that function returns negative values on error...
Please change that with a patch ontop of the move.
Thanks.
-- Regards/Gruss, Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --
| |