Messages in this thread | | | Date | Thu, 24 Jun 2021 16:29:30 +0530 | From | "Naveen N. Rao" <> | Subject | Re: [PATCH v2] powerpc/kprobes: Fix Oops by passing ppc_inst as a pointer to emulate_step() on ppc32 |
| |
Christophe Leroy wrote: > From: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> > > Trying to use a kprobe on ppc32 results in the below splat: > BUG: Unable to handle kernel data access on read at 0x7c0802a6 > Faulting instruction address: 0xc002e9f0 > Oops: Kernel access of bad area, sig: 11 [#1] > BE PAGE_SIZE=4K PowerPC 44x Platform > Modules linked in: > CPU: 0 PID: 89 Comm: sh Not tainted 5.13.0-rc1-01824-g3a81c0495fdb #7 > NIP: c002e9f0 LR: c0011858 CTR: 00008a47 > REGS: c292fd50 TRAP: 0300 Not tainted (5.13.0-rc1-01824-g3a81c0495fdb) > MSR: 00009000 <EE,ME> CR: 24002002 XER: 20000000 > DEAR: 7c0802a6 ESR: 00000000 > <snip> > NIP [c002e9f0] emulate_step+0x28/0x324 > LR [c0011858] optinsn_slot+0x128/0x10000 > Call Trace: > opt_pre_handler+0x7c/0xb4 (unreliable) > optinsn_slot+0x128/0x10000 > ret_from_syscall+0x0/0x28 > > The offending instruction is: > 81 24 00 00 lwz r9,0(r4) > > Here, we are trying to load the second argument to emulate_step(): > struct ppc_inst, which is the instruction to be emulated. On ppc64, > structures are passed in registers when passed by value. However, per > the ppc32 ABI, structures are always passed to functions as pointers. > This isn't being adhered to when setting up the call to emulate_step() > in the optprobe trampoline. Fix the same. > > Fixes: eacf4c0202654a ("powerpc: Enable OPTPROBES on PPC32") > Cc: stable@vger.kernel.org > Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> > --- > v2: Rebased on powerpc/merge 7f030e9d57b8 > Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Thanks for rebasing this!
I think git am drops everything after three dashes, so applying this patch will drop your SOB. The recommended style (*) for adding a changelog is to include it within [] before the second SOB.
- Naveen
(*) https://www.kernel.org/doc/html/latest/maintainer/modifying-patches.html
| |