Hi Ard, Please see the bisection report below about a boot failure on ox820-cloudengines-pogoplug-series-3. There was also a bisection yesterday with next-20201216 which landed on the same commit, on the same platform and also with oxnas_v6_defconfig. I'm not aware of any other platform on kernelci.org showing the same regression.
Hope this helps! Best wishes, Guillaume On 18/12/2020 10:51, KernelCI bot wrote: > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * > * This automated bisection report was sent to you on the basis * > * that you may be involved with the breaking commit it has * > * found. No manual investigation has been done to verify it, * > * and the root cause of the problem may be somewhere else. * > * * > * If you do send a fix, please include this trailer: * > * Reported-by: "kernelci.org bot" <b...@kernelci.org> * > * * > * Hope this helps! * > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * > > next/master bisection: baseline.login on ox820-cloudengines-pogoplug-series-3 > > Summary: > Start: 90cc8cf2d1ab Add linux-next specific files for 20201217 > Plain log: > https://storage.kernelci.org/next/master/next-20201217/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/baseline-ox820-cloudengines-pogoplug-series-3.txt > HTML log: > https://storage.kernelci.org/next/master/next-20201217/arm/oxnas_v6_defconfig/gcc-8/lab-baylibre/baseline-ox820-cloudengines-pogoplug-series-3.html > Result: f77ac2e378be ARM: 9030/1: entry: omit FP emulation for UND > exceptions taken in kernel mode > > Checks: > revert: PASS > verify: PASS > > Parameters: > Tree: next > URL: > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git > Branch: master > Target: ox820-cloudengines-pogoplug-series-3 > CPU arch: arm > Lab: lab-baylibre > Compiler: gcc-8 > Config: oxnas_v6_defconfig > Test case: baseline.login > > Breaking commit found: > > ------------------------------------------------------------------------------- > commit f77ac2e378be9dd61eb88728f0840642f045d9d1 > Author: Ard Biesheuvel <a...@kernel.org> > Date: Thu Nov 19 18:09:16 2020 +0100 > > ARM: 9030/1: entry: omit FP emulation for UND exceptions taken in kernel > mode > > There are a couple of problems with the exception entry code that deals > with FP exceptions (which are reported as UND exceptions) when building > the kernel in Thumb2 mode: > - the conditional branch to vfp_kmode_exception in vfp_support_entry() > may be out of range for its target, depending on how the linker decides > to arrange the sections; > - when the UND exception is taken in kernel mode, the emulation handling > logic is entered via the 'call_fpe' label, which means we end up using > the wrong value/mask pairs to match and detect the NEON opcodes. > > Since UND exceptions in kernel mode are unlikely to occur on a hot path > (as opposed to the user mode version which is invoked for VFP support > code and lazy restore), we can use the existing undef hook machinery for > any kernel mode instruction emulation that is needed, including calling > the existing vfp_kmode_exception() routine for unexpected cases. So drop > the call to call_fpe, and instead, install an undef hook that will get > called for NEON and VFP instructions that trigger an UND exception in > kernel mode. > > While at it, make sure that the PC correction is accurate for the > execution mode where the exception was taken, by checking the PSR > Thumb bit. > > Cc: Dmitry Osipenko <dig...@gmail.com> > Cc: Kees Cook <keesc...@chromium.org> > Fixes: eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input sections") > Signed-off-by: Ard Biesheuvel <a...@kernel.org> > Reviewed-by: Linus Walleij <linus.wall...@linaro.org> > Reviewed-by: Nick Desaulniers <ndesaulni...@google.com> > Signed-off-by: Russell King <rmk+ker...@armlinux.org.uk> > > diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S > index c4220f51fcf3..0ea8529a4872 100644 > --- a/arch/arm/kernel/entry-armv.S > +++ b/arch/arm/kernel/entry-armv.S > @@ -252,31 +252,10 @@ __und_svc: > #else > svc_entry > #endif > - @ > - @ call emulation code, which returns using r9 if it has emulated > - @ the instruction, or the more conventional lr if we are to treat > - @ this as a real undefined instruction > - @ > - @ r0 - instruction > - @ > -#ifndef CONFIG_THUMB2_KERNEL > - ldr r0, [r4, #-4] > -#else > - mov r1, #2 > - ldrh r0, [r4, #-2] @ Thumb instruction at LR - 2 > - cmp r0, #0xe800 @ 32-bit instruction if xx >= 0 > - blo __und_svc_fault > - ldrh r9, [r4] @ bottom 16 bits > - add r4, r4, #2 > - str r4, [sp, #S_PC] > - orr r0, r9, r0, lsl #16 > -#endif > - badr r9, __und_svc_finish > - mov r2, r4 > - bl call_fpe > > mov r1, #4 @ PC correction to apply > -__und_svc_fault: > + THUMB( tst r5, #PSR_T_BIT ) @ exception taken in > Thumb mode? > + THUMB( movne r1, #2 ) @ if so, fix up PC > correction > mov r0, sp @ struct pt_regs *regs > bl __und_fault > > diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S > index 4fcff9f59947..d5837bf05a9a 100644 > --- a/arch/arm/vfp/vfphw.S > +++ b/arch/arm/vfp/vfphw.S > @@ -79,11 +79,6 @@ ENTRY(vfp_support_entry) > DBGSTR3 "instr %08x pc %08x state %p", r0, r2, r10 > > .fpu vfpv2 > - ldr r3, [sp, #S_PSR] @ Neither lazy restore nor FP exceptions > - and r3, r3, #MODE_MASK @ are supported in kernel mode > - teq r3, #USR_MODE > - bne vfp_kmode_exception @ Returns through lr > - > VFPFMRX r1, FPEXC @ Is the VFP enabled? > DBGSTR1 "fpexc %08x", r1 > tst r1, #FPEXC_EN > diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c > index 8c9e7f9f0277..c3b6451c18bd 100644 > --- a/arch/arm/vfp/vfpmodule.c > +++ b/arch/arm/vfp/vfpmodule.c > @@ -23,6 +23,7 @@ > #include <asm/cputype.h> > #include <asm/system_info.h> > #include <asm/thread_notify.h> > +#include <asm/traps.h> > #include <asm/vfp.h> > > #include "vfpinstr.h" > @@ -642,7 +643,9 @@ static int vfp_starting_cpu(unsigned int unused) > return 0; > } > > -void vfp_kmode_exception(void) > +#ifdef CONFIG_KERNEL_MODE_NEON > + > +static int vfp_kmode_exception(struct pt_regs *regs, unsigned int instr) > { > /* > * If we reach this point, a floating point exception has been raised > @@ -660,9 +663,51 @@ void vfp_kmode_exception(void) > pr_crit("BUG: unsupported FP instruction in kernel mode\n"); > else > pr_crit("BUG: FP instruction issued in kernel mode with FP unit > disabled\n"); > + pr_crit("FPEXC == 0x%08x\n", fmrx(FPEXC)); > + return 1; > } > > -#ifdef CONFIG_KERNEL_MODE_NEON > +static struct undef_hook vfp_kmode_exception_hook[] = {{ > + .instr_mask = 0xfe000000, > + .instr_val = 0xf2000000, > + .cpsr_mask = MODE_MASK | PSR_T_BIT, > + .cpsr_val = SVC_MODE, > + .fn = vfp_kmode_exception, > +}, { > + .instr_mask = 0xff100000, > + .instr_val = 0xf4000000, > + .cpsr_mask = MODE_MASK | PSR_T_BIT, > + .cpsr_val = SVC_MODE, > + .fn = vfp_kmode_exception, > +}, { > + .instr_mask = 0xef000000, > + .instr_val = 0xef000000, > + .cpsr_mask = MODE_MASK | PSR_T_BIT, > + .cpsr_val = SVC_MODE | PSR_T_BIT, > + .fn = vfp_kmode_exception, > +}, { > + .instr_mask = 0xff100000, > + .instr_val = 0xf9000000, > + .cpsr_mask = MODE_MASK | PSR_T_BIT, > + .cpsr_val = SVC_MODE | PSR_T_BIT, > + .fn = vfp_kmode_exception, > +}, { > + .instr_mask = 0x0c000e00, > + .instr_val = 0x0c000a00, > + .cpsr_mask = MODE_MASK, > + .cpsr_val = SVC_MODE, > + .fn = vfp_kmode_exception, > +}}; > + > +static int __init vfp_kmode_exception_hook_init(void) > +{ > + int i; > + > + for (i = 0; i < ARRAY_SIZE(vfp_kmode_exception_hook); i++) > + register_undef_hook(&vfp_kmode_exception_hook[i]); > + return 0; > +} > +core_initcall(vfp_kmode_exception_hook_init); > > /* > * Kernel-side NEON support functions > ------------------------------------------------------------------------------- > > > Git bisection log: > > ------------------------------------------------------------------------------- > git bisect start > # good: [31f6551ad75608d9c71fd4d3548c33f1abc52093] cifs: handle "guest" mount > parameter > git bisect good 31f6551ad75608d9c71fd4d3548c33f1abc52093 > # bad: [90cc8cf2d1ab87d708ebc311ac104ccbbefad9fc] Add linux-next specific > files for 20201217 > git bisect bad 90cc8cf2d1ab87d708ebc311ac104ccbbefad9fc > # good: [3db1a3fa98808aa90f95ec3e0fa2fc7abf28f5c9] Merge tag > 'staging-5.11-rc1' of > git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging > git bisect good 3db1a3fa98808aa90f95ec3e0fa2fc7abf28f5c9 > # bad: [4538b80cd2885c885e3bf06e5103bc0f214c11ee] Merge remote-tracking > branch 'arm-soc/for-next' > git bisect bad 4538b80cd2885c885e3bf06e5103bc0f214c11ee > # good: [5ee863bec794f30bdf7fdf57ce0d9f579b0d1aa3] Merge branch > 'parisc-5.11-1' of > git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux > git bisect good 5ee863bec794f30bdf7fdf57ce0d9f579b0d1aa3 > # good: [fb10b701887b9fce88aacc06ca4b6c9160ca7a66] Merge branch 'arm/dt' into > for-next > git bisect good fb10b701887b9fce88aacc06ca4b6c9160ca7a66 > # good: [821a8a63a6b55ee5325e07bf5ab7d7a1752009d1] Merge remote-tracking > branch 'asm-generic/master' > git bisect good 821a8a63a6b55ee5325e07bf5ab7d7a1752009d1 > # good: [7debceff46eef5350bf2b62494c7772f78b22257] Merge branch 'arm/dt' into > for-next > git bisect good 7debceff46eef5350bf2b62494c7772f78b22257 > # bad: [b383a1412e0df59c556abb93c1fa2399e91b6102] Merge remote-tracking > branch 'arm64/for-next/core' > git bisect bad b383a1412e0df59c556abb93c1fa2399e91b6102 > # good: [113eb4ce4fc33ef3deda1431497811d43342c0cc] Merge branch > 'for-next/iommu/vt-d' into for-next/iommu/core > git bisect good 113eb4ce4fc33ef3deda1431497811d43342c0cc > # skip: [eb86b15a2c53e2263b7cbad00a0100c8451989dc] Merge branches 'fixes' and > 'misc' into for-next > git bisect skip eb86b15a2c53e2263b7cbad00a0100c8451989dc > # skip: [2a50d6b9cfe96ef5d39b9c3497dcc83a907d00cd] ARM: 9033/1: arm/smp: Drop > the macro S(x,s) > git bisect skip 2a50d6b9cfe96ef5d39b9c3497dcc83a907d00cd > # good: [421015713b306e47af95d4d61cdfbd96d462e4cb] ARM: 9017/2: Enable KASan > for ARM > git bisect good 421015713b306e47af95d4d61cdfbd96d462e4cb > # good: [2c736bb4087f2cb949cbbaf4148733131b8466dc] Merge tag > 'arm-adrl-replacement-for-v5.11' of > git://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux into devel-stable > git bisect good 2c736bb4087f2cb949cbbaf4148733131b8466dc > # skip: [3597a10e4c444f3d4d6a64bdc98e4585a99301b9] ARM: 9036/1: uncompress: > Fix dbgadtb size parameter name > git bisect skip 3597a10e4c444f3d4d6a64bdc98e4585a99301b9 > # skip: [1205285c7a71c3b7a879e31ec477639f2dac22b1] ARM: 9027/1: head.S: > explicitly map DT even if it lives in the first physical section > git bisect skip 1205285c7a71c3b7a879e31ec477639f2dac22b1 > # good: [71fe89ceb55bc0a85121b757cc8d3fb6ff457263] dma-iommu: remove > __iommu_dma_mmap > git bisect good 71fe89ceb55bc0a85121b757cc8d3fb6ff457263 > # skip: [17fb1a208129e3472ec45be08cbe39601a407e2c] ARM: 9031/1: hyp-stub: > remove unused .L__boot_cpu_mode_offset symbol > git bisect skip 17fb1a208129e3472ec45be08cbe39601a407e2c > # good: [95d1718c961e49cfa02995ce1587a22cd7e2fbf5] Merge remote-tracking > branch 'arm64/for-next/iommu/core' into for-next/core > git bisect good 95d1718c961e49cfa02995ce1587a22cd7e2fbf5 > # skip: [0fe88ade3f937d6efc276901a56be6575a5a2171] ARM: 9032/1: arm/mm: > Convert PUD level pgtable helper macros into functions > git bisect skip 0fe88ade3f937d6efc276901a56be6575a5a2171 > # good: [730b5764ea8526e48bdb85a24ed96d62de435940] ARM: 9024/1: Drop useless > cast of "u64" to "long long" > git bisect good 730b5764ea8526e48bdb85a24ed96d62de435940 > # good: [4d576cab16f57e1f87978f6997a725179398341e] ARM: 9028/1: disable KASAN > in call stack capturing routines > git bisect good 4d576cab16f57e1f87978f6997a725179398341e > # skip: [3bdf1a7503d61d2241f93f36e9c0d8a0d444bc5c] ARM: 9037/1: uncompress: > Add OF_DT_MAGIC macro > git bisect skip 3bdf1a7503d61d2241f93f36e9c0d8a0d444bc5c > # bad: [f77ac2e378be9dd61eb88728f0840642f045d9d1] ARM: 9030/1: entry: omit FP > emulation for UND exceptions taken in kernel mode > git bisect bad f77ac2e378be9dd61eb88728f0840642f045d9d1 > # good: [3c9f5708b7aed6a963e2aefccbd1854802de163e] ARM: 9029/1: Make iwmmxt.S > support Clang's integrated assembler > git bisect good 3c9f5708b7aed6a963e2aefccbd1854802de163e > # first bad commit: [f77ac2e378be9dd61eb88728f0840642f045d9d1] ARM: 9030/1: > entry: omit FP emulation for UND exceptions taken in kernel mode > ------------------------------------------------------------------------------- > > > -=-=-=-=-=-=-=-=-=-=-=- > Groups.io Links: You receive all messages sent to this group. > View/Reply Online (#4773): https://groups.io/g/kernelci-results/message/4773 > Mute This Topic: https://groups.io/mt/79040317/924702 > Group Owner: kernelci-results+ow...@groups.io > Unsubscribe: https://groups.io/g/kernelci-results/unsub > [guillaume.tuc...@collabora.com] > -=-=-=-=-=-=-=-=-=-=-=- > >
