Messages in this thread | | | From | Jann Horn <> | Date | Thu, 11 Jul 2019 23:04:35 +0200 | Subject | Re: objtool crashes on clang output (drivers/hwmon/pmbus/adm1275.o) |
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On Thu, Jul 11, 2019 at 11:00 PM Arnd Bergmann <arnd@arndb.de> wrote: > > On Thu, Jul 11, 2019 at 7:26 PM Josh Poimboeuf <jpoimboe@redhat.com> wrote: > > > > On Thu, Jul 11, 2019 at 02:40:06PM +0200, Arnd Bergmann wrote: > > > During randconfig testing with clang-9, I came across an object file > > > that makes objtool segfault, see attachment. Let me know if you need > > > more information to > > > debug this. > > > > > > I also get a ton of objtool warnings building random configurations, but Nick > > > mentioned that there is still a bug related to asm-goto in the build I'm using > > > that may be the root cause. Once I have a fixed clang-9 build, I can have a look > > > at those as well. > > > > Seg fault fix: > > Thanks for the fix! testing it over night now, will let you know tomorrow > if problems remain. > > I wonder if this is also related to several warnings I get about switch > tables like: > > drivers/usb/misc/sisusbvga/sisusb.o: warning: objtool: > sisusb_write_mem_bulk()+0x588: can't find switch jump table > > drivers/gpu/drm/amd/amdgpu/../display/dc/dce110/dce110_mem_input_v.o: > warning: objtool: dce_mem_input_v_program_pte_vm()+0x46e: can't find > switch jump table > drivers/gpu/drm/amd/amdgpu/../display/dc/dce110/dce110_opp_csc_v.o: > warning: objtool: dce110_opp_v_set_csc_default()+0x714: can't find > switch jump table > drivers/gpu/drm/nouveau/nvkm/subdev/clk/nv50.o: warning: objtool: > nv50_clk_read()+0x15c: can't find switch jump table > drivers/media/dvb-frontends/cxd2880/cxd2880_tnrdmd_dvbt2.o: warning: > objtool: x_tune_dvbt2_demod_setting()+0x992: can't find switch jump > table > drivers/media/tuners/mt2063.o: warning: objtool: > MT2063_SetReceiverMode()+0x24d: can't find switch jump table > drivers/mmc/host/tifm_sd.o: warning: objtool: tifm_sd_exec()+0x7e: > can't find switch jump table > drivers/mtd/nand/raw/fsl_ifc_nand.o: warning: objtool: > fsl_ifc_nand_probe()+0x4c7: can't find switch jump table > drivers/net/can/at91_can.o: warning: objtool: at91_irq()+0x347: can't > find switch jump table > drivers/net/phy/phylink.o: warning: objtool: > phylink_mac_config()+0x2b5: can't find switch jump table > drivers/regulator/max8973-regulator.o: warning: objtool: > max8973_probe()+0x736: can't find switch jump table > drivers/regulator/tps80031-regulator.o: warning: objtool: > tps80031_regulator_probe()+0x143: can't find switch jump table > drivers/tty/cyclades.o: warning: objtool: cy_set_line_char()+0x86c: > can't find switch jump table > drivers/tty/serial/jsm/jsm_cls.o: warning: objtool: cls_param()+0x10b: > can't find switch jump table > drivers/tty/serial/jsm/jsm_neo.o: warning: objtool: neo_param()+0x151: > can't find switch jump table > drivers/usb/core/hub.o: warning: objtool: hub_probe()+0x920: can't > find switch jump table > drivers/usb/misc/sisusbvga/sisusb.o: warning: objtool: > sisusb_write_mem_bulk()+0x4db: can't find switch jump table > kernel/rcu/tree.o: warning: objtool: rcu_note_context_switch()+0x6b8: > can't find switch jump table > lib/zstd/decompress.o: warning: objtool: > ZSTD_decodeLiteralsBlock()+0x5e: can't find switch jump table > > If you want to have a look, I can provide object files and/or reduced test > cases for this. My guess is that it is unrelated to the warnings that Nick > saw for asm-goto.
I was playing around with building the kernel with LLVM a few months ago and used this local patch, but didn't get around to submitting upstream because I couldn't reproduce the problem for some reason. I think the warnings you're getting sound like what I saw back then: https://gist.github.com/thejh/0434662728afb95d72455bf30ece5817
Quoting the commit message from that patch:
==== With clang from git master, code can be generated where a function contains two indirect jump instructions that use the same switch table. To deal with this case and similar ones properly, convert the switch table parsing to use two passes: ====
Does that sound like what you're seeing?
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