Messages in this thread | | | From | Christian Eggers <> | Subject | Re: CONFIG_THUMB2_KERNEL=y boot failure after Spectre BHB fixes | Date | Tue, 22 Mar 2022 18:49:17 +0100 |
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Hi Nathan, hi Russel,
I stumbled today over the same problem (no output on serial console with v5.15.28-rt36). During `git bisect`, I had also some commits where a few lines of output were visible.
At commit 8d9d651ff227 ("ARM: use LOADADDR() to get load address of sections"), the system boots up to here:
start_kernel() +--setup_arch() +--paging_init() +--devicemaps_init() +--eary_trap_init(vectors_base = 0xC7FFE000) +--copy_from_lma(vectors_base = 0xC7FFE000, __vectors_start=0x0, __vectors_end=0x20) +--__memcpy()
copy_template.S:113 ldr8w r1, r3, r4, r5, r6, r7, r8, ip, lr, abort=20f r1 = 0
With the final v5.15.28-rt36 I found out that the system boots fine after disabling CONFIG_HARDEN_BRANCH_HISTORY.
Is there anything else I could analyze? My SoC system is a NXP i.MX6LL with a ARMv7 core. I have access to a JTAG debugger.
regards Christian
On Thursday, 10 March 2022, 20:16:48 CET, Nathan Chancellor wrote: > Hi Russell, > > Apologies if this has already been reported, I did not see anything when > sifting through lore.kernel.org and I can still reproduce this with > current mainline (1db333d9a51f). > > I noticed a QEMU boot failure with multi_v7_defconfig with > CONFIG_THUMB2_KERNEL=y in our continuous integration [1]. It does not > appear to be compiler specific, as it reproduces with a bunch of > different clang versions and GCC 11.2.0 (I didn't try other GCC > versions). > > At commit 04e91b732476 ("ARM: early traps initialisation"), everything > boots fine. > > At commit 8d9d651ff227 ("ARM: use LOADADDR() to get load address of > sections"), there is no output from QEMU at all. > > At commit b9baf5c8c5c3 ("ARM: Spectre-BHB workaround"), there is some > output but the boot still hangs before init. I have included a log of > the output of QEMU at this revision along with the command line I am > using, which comes from [2]. If I disable CONFIG_HARDEN_BRANCH_HISTORY, > the kernel boots. > > If there is any further information I can provide or patches I can try, > I am happy to do so. > > [1]: https://github.com/ClangBuiltLinux/continuous-integration2/runs/5496036256?check_suite_focus=true > [2]: https://github.com/ClangBuiltLinux/boot-utils > > Cheers, > Nathan >
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