Message ID | 5bdc8cbc9a95d0779e27c9ddbf42b40f51f883c0.1624425798.git.christophe.leroy@csgroup.eu (mailing list archive) |
---|---|
State | Accepted |
Headers | show |
Series | [v2] powerpc/kprobes: Fix Oops by passing ppc_inst as a pointer to emulate_step() on ppc32 | expand |
Context | Check | Description |
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snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (7f030e9d57b8ff6025bde4162f42378e6081126a) |
snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 14 lines checked |
snowpatch_ozlabs/needsstable | success | Patch is tagged for stable |
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
Le 24/06/2021 à 12:59, Naveen N. Rao a écrit : > 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. > Yes, I saw that after sending the mail. Usually I add a signed-off-by with 'git --amend -s' when I add the history, so it goes before the '---' I'm adding. This time I must have forgotten the '-s' so it was added by the 'git format-patch -s' which is in my submit script, and so it was added at the end. It's not really a big deal, up to Michael to either move it at the right place or discard it, I don't really mind. Do the easiest for you. Thanks Christophe
Christophe Leroy <christophe.leroy@csgroup.eu> writes: > Le 24/06/2021 à 12:59, Naveen N. Rao a écrit : >> 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. > > Yes, I saw that after sending the mail. Usually I add a signed-off-by with 'git --amend -s' when I > add the history, so it goes before the '---' I'm adding. > > This time I must have forgotten the '-s' so it was added by the 'git format-patch -s' which is in my > submit script, and so it was added at the end. > > It's not really a big deal, up to Michael to either move it at the right place or discard it, I > don't really mind. Do the easiest for you. I just added Christophe's SoB. cheers
On Wed, 23 Jun 2021 05:23:30 +0000 (UTC), Christophe Leroy wrote: > 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 > > [...] Applied to powerpc/next. [1/1] powerpc/kprobes: Fix Oops by passing ppc_inst as a pointer to emulate_step() on ppc32 https://git.kernel.org/powerpc/c/511eea5e2ccdfdbf3d626bde0314e551f247dd18 cheers
diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c index 2b8fe40069ad..53facb4b377f 100644 --- a/arch/powerpc/kernel/optprobes.c +++ b/arch/powerpc/kernel/optprobes.c @@ -228,8 +228,12 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p) /* * 3. load instruction to be emulated into relevant register, and */ - temp = ppc_inst_read(p->ainsn.insn); - patch_imm_load_insns(ppc_inst_as_ulong(temp), 4, buff + TMPL_INSN_IDX); + if (IS_ENABLED(CONFIG_PPC64)) { + temp = ppc_inst_read(p->ainsn.insn); + patch_imm_load_insns(ppc_inst_as_ulong(temp), 4, buff + TMPL_INSN_IDX); + } else { + patch_imm_load_insns((unsigned long)p->ainsn.insn, 4, buff + TMPL_INSN_IDX); + } /* * 4. branch back from trampoline