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[Bug 1844597] Re: fc1120a7f5f2d4b601003205c598077d3eb11ad2 causes a kern
From: |
Peter Maydell |
Subject: |
[Bug 1844597] Re: fc1120a7f5f2d4b601003205c598077d3eb11ad2 causes a kernel panic in vfp_init on a clang built kernel |
Date: |
Fri, 20 Sep 2019 17:49:38 -0000 |
Should be fixed by:
https://patchew.org/QEMU/address@hidden/
(which allows me to boot the kernel you attached at least as far as "didn't
find a root filesystem").
** Changed in: qemu
Status: New => In Progress
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https://bugs.launchpad.net/bugs/1844597
Title:
fc1120a7f5f2d4b601003205c598077d3eb11ad2 causes a kernel panic in
vfp_init on a clang built kernel
Status in QEMU:
In Progress
Bug description:
Commit 4cdabee7d6d2 ("ARM: configs: aspeed_g5: Enable AST2600") [1] in
the Linux kernel enabled CONFIG_VFP. When building this config with
Clang, the resulting kernel does not boot after commit fc1120a7f5
("target/arm: Implement NSACR gating of floating point") [2] (present
since the 4.1.0 release).
The QEMU command:
qemu-system-arm -m 512m \
-machine romulus-bmc \
-no-reboot \
-dtb out/arch/arm/boot/dts/aspeed-bmc-opp-romulus.dtb \
-initrd rootfs.cpio \
-display none \
-serial mon:stdio \
-kernel ${KBF}/arch/arm/boot/zImage
If it is needed, the rootfs we are using is provided at a link below
[3].
Debugging with QEMU reveals that the kernel panics in vfp_init,
specifically at the line:
vfpsid = fmrx(FPSID);
in arch/arm/vfp/vfpmodule.c because of an illegal instruction:
[ 0.058685] VFP support v0.3:
[ 0.059159] Internal error: Oops - undefined instruction: 0 [#1] SMP ARM
[ 0.059525] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
5.3.0-next-20190918-dirty #1
[ 0.059547] Hardware name: Generic DT based system
[ 0.059702] PC is at vfp_init+0x50/0x1f4
[ 0.059721] LR is at vfp_init+0x4c/0x1f4
[ 0.059738] pc : [<80b0383c>] lr : [<80b03838>] psr: 60000153
[ 0.059756] sp : 9e497ec0 ip : 00000020 fp : 9e497ed8
[ 0.059773] r10: 00000000 r9 : ffffe000 r8 : 80c06048
[ 0.059792] r7 : 00000000 r6 : 80c0caac r5 : 80c6c418 r4 : 80b037ec
[ 0.059811] r3 : 00000000 r2 : 339aa372 r1 : 00000000 r0 : 00000012
[ 0.059859] Flags: nZCv IRQs on FIQs off Mode SVC_32 ISA ARM Segment
none
[ 0.059883] Control: 00c5387d Table: 80004008 DAC: 00000051
[ 0.059997] Process swapper/0 (pid: 1, stack limit = 0x(ptrval))
[ 0.060048] Stack: (0x9e497ec0 to 0x9e498000)
[ 0.060205] 7ec0: 80b037ec 80b6bf0c 80b037ec ffffffff 00000000 00000000
9e497f48 80b01100
[ 0.060310] 7ee0: 00000000 9eeff9e0 80a85734 809eb9be 00000000 8014b7f4
9eeff9e0 80a85734
[ 0.060408] 7f00: 9e497f48 8014b7f4 000000a4 00000001 00000001 00000000
80b0133c 9e497f38
[ 0.060509] 7f20: 00000000 9eeff9d5 339aa372 80b6be80 80b6bf0c 00000000
00000000 00000000
[ 0.060606] 7f40: 00000000 00000000 9e497f70 80b01864 00000001 00000001
00000000 80b0133c
[ 0.060703] 7f60: 00000001 8085d268 00000000 00000000 9e497f80 80b01758
00000000 00000000
[ 0.060800] 7f80: 9e497f90 80b015e4 00000000 8085d268 9e497fa8 8085d27c
00000000 8085d268
[ 0.060897] 7fa0: 00000000 00000000 00000000 801010e8 00000000 00000000
00000000 00000000
[ 0.060993] 7fc0: 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000
[ 0.061090] 7fe0: 00000000 00000000 00000000 00000000 00000013 00000000
00000000 00000000
[ 0.061625] [<80b0383c>] (vfp_init) from [<80b01100>]
(do_one_initcall+0xa8/0x1e0)
[ 0.061722] [<80b01100>] (do_one_initcall) from [<80b01864>]
(do_initcall_level+0xfc/0x12c)
[ 0.061742] [<80b01864>] (do_initcall_level) from [<80b01758>]
(do_basic_setup+0x2c/0x3c)
[ 0.061759] [<80b01758>] (do_basic_setup) from [<80b015e4>]
(kernel_init_freeable+0x68/0x104)
[ 0.061777] [<80b015e4>] (kernel_init_freeable) from [<8085d27c>]
(kernel_init+0x14/0x26c)
[ 0.061798] [<8085d27c>] (kernel_init) from [<801010e8>]
(ret_from_fork+0x14/0x2c)
[ 0.061835] Exception stack(0x9e497fb0 to 0x9e497ff8)
[ 0.061896] 7fa0: 00000000 00000000
00000000 00000000
[ 0.061998] 7fc0: 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000
[ 0.062080] 7fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[ 0.062263] Code: e5860000 e59f0174 ebd9d8fc e59f5170 (eef04a10)
[ 0.062679] ---[ end trace 2d338c91e4e74562 ]---
Before fc1120a7f5:
[ 0.069418] VFP support v0.3: implementor 41 architecture 1 part 20
variant b rev 5
Should you need to reproduce this locally:
* clang 9.0.0 or later is needed to build this config. If you do not
have easy access to such a build, we have a clang build script
available [4] that can help with this:
% ./build-llvm.py --branch llvmorg-9.0.0-rc6 \
--build-stage1-only \
--projects clang \
--targets ARM
* Because of an unrelated build issue, linux-next needs to be used (or
the singular patch that resolves it needs to be cherry-picked on top
of 4cdabee7d6d2 [5]). The kernel make command used:
% make -j$(nproc) -s \
ARCH=arm \
CC=clang \
CROSS_COMPILE=arm-linux-gnueabi- \
O=out \
distclean aspeed_g5_defconfig all
[1]: https://git.kernel.org/linus/4cdabee7d6d2e439fea726a101e448c4ca6837f4
[2]:
https://git.qemu.org/?p=qemu.git;a=commit;h=fc1120a7f5f2d4b601003205c598077d3eb11ad2
[3]:
https://github.com/ClangBuiltLinux/continuous-integration/blob/800d84bf8c55ee04c50ed4c78144a96d889a91c5/images/arm/rootfs.cpio
[4]: https://github.com/ClangBuiltLinux/tc-build
[5]:
http://git.armlinux.org.uk/cgit/linux-arm.git/commit/?id=7b3948597372e5a6b314208ac320362c204b7f0f
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- [Qemu-devel] [Bug 1844597] [NEW] fc1120a7f5f2d4b601003205c598077d3eb11ad2 causes a kernel panic in vfp_init on a clang built kernel, Nathan Chancellor, 2019/09/18
- [Bug 1844597] Re: fc1120a7f5f2d4b601003205c598077d3eb11ad2 causes a kernel panic in vfp_init on a clang built kernel, Peter Maydell, 2019/09/20
- [Bug 1844597] Re: fc1120a7f5f2d4b601003205c598077d3eb11ad2 causes a kernel panic in vfp_init on a clang built kernel, Nathan Chancellor, 2019/09/20
- [Bug 1844597] Re: fc1120a7f5f2d4b601003205c598077d3eb11ad2 causes a kernel panic in vfp_init on a clang built kernel, Nathan Chancellor, 2019/09/20
- [Bug 1844597] Re: fc1120a7f5f2d4b601003205c598077d3eb11ad2 causes a kernel panic in vfp_init on a clang built kernel, Peter Maydell, 2019/09/20
- [Bug 1844597] Re: fc1120a7f5f2d4b601003205c598077d3eb11ad2 causes a kernel panic in vfp_init on a clang built kernel,
Peter Maydell <=
- [Bug 1844597] Re: fc1120a7f5f2d4b601003205c598077d3eb11ad2 causes a kernel panic in vfp_init on a clang built kernel, Nathan Chancellor, 2019/09/20