On Tue, Mar 08, 2016 at 06:33:57PM +1100, Balbir Singh wrote: > Changelog v5: > 1. Removed the mini-stack frame created for klp_return_helper. > As a result of the mini-stack frame, function with > 8 > arguments could not be patched Did you get my previous mails? Those functions only require special care, the _can_ be patched. In general, writing replacement functions always requires attention! Have you *tested* this patch? Replacing a function in the kernel? Replacing a function in a module? For local calls? For global calls? I strongly doubt so because it does not work this way. To be fair, my last mail still was not 100% correct, but the conclusion that the mini frame is not needed at all is invalid. Please leave it as it was, I'm working on a test / demonstrator for how to handle these. > + * Why do we need this? > + * After patching we need to return to a trampoline return function > + * that guarantees that we restore the TOC and return to the correct > + * caller back > + */ > + std r2, 24(r1) /* save TOC now, unconditionally. */ > + subf r0, r2, r0 /* Calculate offset from current TOC */ > + stw r0, 12(r1) /* Of the final LR and save it in CR+4 */ > + bl 5f > +5: mflr r12 > + addi r12, r12, (klp_return_helper + 4 - .)@l > + std r12, LRSAVE(r1) [...] > + * maybe inserting a klp_return_helper frame or not. > +*/ > +klp_return_helper: > + ld r2, 24(r1) /* restore TOC (saved by ftrace_caller) */ > + lwa r0, 12(r1) /* Load from CR+4, offset of LR w.r.t TOC */ > + add r0, r0, r2 /* Add the offset to current TOC */ > + std r0, LRSAVE(r1) /* save the real return address */ > + mtlr r0 > + blr > +#endif NAKed-by: Torsten Duwe <duwe@xxxxxxx> Torsten -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
