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From:   Anders Roxell <anders.roxell@linaro.org>
Date:   Mon, 6 Jul 2020 14:00:23 +0200
Message-ID: <CADYN=9KfRXVK_1Msi6dzKUzvGNbxVPV2DxvEE7_Z2Mg7piht=w@mail.gmail.com>
Subject: Re: [PATCH] kbuild: introduce ccflags-remove-y and asflags-remove-y
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     Michael Ellerman <mpe@ellerman.id.au>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Ingo Molnar <mingo@redhat.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Paul Mackerras <paulus@samba.org>,
        Rich Felker <dalias@libc.org>,
        Russell King <linux@armlinux.org.uk>,
        Steven Rostedt <rostedt@goodmis.org>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        Linux-sh list <linux-sh@vger.kernel.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
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On Mon, 6 Jul 2020 at 13:24, Anders Roxell <anders.roxell@linaro.org> wrote:
>
> Hi,
>
> When I built an allmodconfig kernel for arm64, and boot that in qemu
> guest I see the following issues:
>
> [...]
> [   10.451561][    T1] Testing tracer function: PASSED
> [   33.087895][    T1] Testing dynamic ftrace: .. filter did not
> filter .. FAILED!
> [   51.127094][    T1] ------------[ cut here ]------------
> [   51.132387][    T1] WARNING: CPU: 0 PID: 1 at
> kernel/trace/trace.c:1814 run_tracer_selftest+0x314/0x40c
> [   51.140805][    T1] Modules linked in:
> [   51.145398][    T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
> 5.8.0-rc3-next-20200703-00004-g8cd4bc531754 #1
> [   51.154146][    T1] Hardware name: linux,dummy-virt (DT)
> [   51.159536][    T1] pstate: 80400005 (Nzcv daif +PAN -UAO BTYPE=--)
> [   51.165711][    T1] pc : run_tracer_selftest+0x314/0x40c
> [   51.171167][    T1] lr : run_tracer_selftest+0x308/0x40c
> [   51.176475][    T1] sp : ffff000069c07c40
> [   51.180855][    T1] x29: ffff000069c07c40 x28: ffffa00015e80320
> [   51.187187][    T1] x27: ffffa00013e074a0 x26: ffffa000150f22ee
> [   51.193520][    T1] x25: ffffa000125b35a0 x24: ffffa00013f6a000
> [   51.199868][    T1] x23: ffffa00013f6adc0 x22: 00000000ffffffff
> [   51.206225][    T1] x21: ffffa000150f2250 x20: ffffa00015e801c0
> [   51.212582][    T1] x19: ffffa00015e7fa80 x18: 0000000000002750
> [   51.218887][    T1] x17: 00000000000014c0 x16: 00000000000016f0
> [   51.225229][    T1] x15: 00000000000014f8 x14: ffffa0001000a3c8
> [   51.231584][    T1] x13: ffffa000124a5fb8 x12: ffff80000d494822
> [   51.237935][    T1] x11: 1fffe0000d494821 x10: ffff80000d494821
> [   51.244293][    T1] x9 : ffffa000101763b0 x8 : ffff000069c077d7
> [   51.250704][    T1] x7 : 0000000000000001 x6 : ffff000069c077d0
> [   51.257060][    T1] x5 : ffff00006a7fc040 x4 : 0000000000000000
> [   51.263423][    T1] x3 : ffffa00010211118 x2 : 8af0509000018b00
> [   51.269757][    T1] x1 : 0000000000000000 x0 : 0000000000000001
> [   51.276084][    T1] Call trace:
> [   51.279934][    T1]  run_tracer_selftest+0x314/0x40c
> [   51.285174][    T1]  init_trace_selftests+0x110/0x31c
> [   51.290391][    T1]  do_one_initcall+0x410/0x960
> [   51.295315][    T1]  kernel_init_freeable+0x430/0x4f0
> [   51.300595][    T1]  kernel_init+0x20/0x1d8
> [   51.305180][    T1]  ret_from_fork+0x10/0x18
> [   51.309741][    T1] irq event stamp: 1401832
> [   51.314399][    T1] hardirqs last  enabled at (1401831):
> [<ffffa0001020d10c>] console_unlock+0xc04/0xd10
> [   51.322973][    T1] hardirqs last disabled at (1401832):
> [<ffffa00010050fe4>] debug_exception_enter+0xbc/0x200
> [   51.331993][    T1] softirqs last  enabled at (1401828):
> [<ffffa000100023a4>] __do_softirq+0x95c/0x9f8
> [   51.340490][    T1] softirqs last disabled at (1401821):
> [<ffffa0001010f7d0>] irq_exit+0x118/0x198
> [   51.348717][    T1] _warn_unseeded_randomness: 5 callbacks suppressed
> [   51.349263][    T1] random: get_random_bytes called from
> print_oops_end_marker+0x48/0x80 with crng_init=0
> [   51.350502][    T1] ---[ end trace c566e8a71c933d3c ]---
> [...]
> [40709.672335][    C0] pool 2: cpus=0 flags=0x5 nice=0 hung=3s
> workers=3 manager: 1455
> [40739.960593][   T26] INFO: lockdep is turned off.
> [40775.312499][   T26] Kernel panic - not syncing: hung_task: blocked tasks
> [40775.341521][   T26] CPU: 0 PID: 26 Comm: khungtaskd Tainted: G
>   W         5.8.0-rc3-next-20200703-00004-g8cd4bc531754 #1
> [40775.352848][   T26] Hardware name: linux,dummy-virt (DT)
> [40775.359304][   T26] Call trace:
> [40775.364148][   T26]  dump_backtrace+0x0/0x418
> [40775.369918][   T26]  show_stack+0x34/0x48
> [40775.375468][   T26]  dump_stack+0x1f4/0x2b0
> [40775.381136][   T26]  panic+0x2dc/0x6ec
> [40775.386430][   T26]  watchdog+0x1400/0x1460
> [40775.392103][   T26]  kthread+0x23c/0x250
> [40775.397548][   T26]  ret_from_fork+0x10/0x18
> [40775.407039][   T26] Kernel Offset: disabled
> [40775.412634][   T26] CPU features: 0x240002,20002004
> [40775.418751][   T26] Memory Limit: none
> [40775.425823][   T26] ---[ end Kernel panic - not syncing: hung_task:
> blocked tasks ]---
>
> The full log can be found here [1].
>
> Without this patch for  'trace_selftest_dynamic' for instance, CC_FLAGS_FTRACE
> was removed from kernel/trace/*, and then added back to
> kernel/trace/trace_selftest_dynamic.
> While with this patch it looks like we add the flag (even though it is
> already there), and then
> removes the flag for all files in kernel/trace/* .

Hi again,

I think the patch below solved the issue for trace_selftest_dynamic. However,
I think there is still differences in lib/* .

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index cc5e3c6aaa20..5632a711921f 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -111,12 +111,12 @@ basename_flags = -DKBUILD_BASENAME=$(call
name-fix,$(basetarget))
 modname_flags  = -DKBUILD_MODNAME=$(call name-fix,$(modname))
 modfile_flags  = -DKBUILD_MODFILE=$(call stringify,$(modfile))

-orig_c_flags   = $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) \
-                 $(ccflags-y) $(CFLAGS_$(target-stem).o)
+orig_c_flags   = $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(ccflags-y)
 _c_flags       = $(filter-out $(ccflags-remove-y)
$(CFLAGS_REMOVE_$(target-stem).o), $(orig_c_flags))
-orig_a_flags   = $(KBUILD_CPPFLAGS) $(KBUILD_AFLAGS) \
-                 $(asflags-y) $(AFLAGS_$(target-stem).o)
+_c_flags      += $(CFLAGS_$(target-stem).o)
+orig_a_flags   = $(KBUILD_CPPFLAGS) $(KBUILD_AFLAGS) $(asflags-y)
 _a_flags       = $(filter-out $(asflags-remove-y)
$(AFLAGS_REMOVE_$(target-stem).o), $(orig_a_flags))
+_a_flags      += $(AFLAGS_$(target-stem).o)
 _cpp_flags     = $(KBUILD_CPPFLAGS) $(cppflags-y)
$(CPPFLAGS_$(target-stem).lds)

 #


>
> Cheers,
> Anders
> [1] https://people.linaro.org/~anders.roxell/output-next-20200703.log
>
> On Tue, 30 Jun 2020 at 04:09, Masahiro Yamada <masahiroy@kernel.org> wrote:
> >
> > On Mon, Jun 29, 2020 at 2:55 PM Michael Ellerman <mpe@ellerman.id.au> wrote:
> > >
> > > Masahiro Yamada <masahiroy@kernel.org> writes:
> > > > CFLAGS_REMOVE_<file>.o works per object, that is, there is no
> > > > convenient way to filter out flags for every object in a directory.
> > > >
> > > > Add ccflags-remove-y and asflags-remove-y to make it easily.
> > > >
> > > > Use ccflags-remove-y to clean up some Makefiles.
> > > >
> > > > Suggested-by: Sami Tolvanen <samitolvanen@google.com>
> > > > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> > > > ---
> > > >
> > > >  arch/arm/boot/compressed/Makefile | 6 +-----
> > > >  arch/powerpc/xmon/Makefile        | 3 +--
> > > >  arch/sh/boot/compressed/Makefile  | 5 +----
> > > >  kernel/trace/Makefile             | 4 ++--
> > > >  lib/Makefile                      | 5 +----
> > > >  scripts/Makefile.lib              | 4 ++--
> > > >  6 files changed, 8 insertions(+), 19 deletions(-)
> > > >
> > > > diff --git a/arch/powerpc/xmon/Makefile b/arch/powerpc/xmon/Makefile
> > > > index 89c76ca35640..55cbcdd88ac0 100644
> > > > --- a/arch/powerpc/xmon/Makefile
> > > > +++ b/arch/powerpc/xmon/Makefile
> > > > @@ -7,8 +7,7 @@ UBSAN_SANITIZE := n
> > > >  KASAN_SANITIZE := n
> > > >
> > > >  # Disable ftrace for the entire directory
> > > > -ORIG_CFLAGS := $(KBUILD_CFLAGS)
> > > > -KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS))
> > > > +ccflags-remove-y += $(CC_FLAGS_FTRACE)
> > >
> > > This could be:
> > >
> > > ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
> > >
> > > Similar to kernel/trace/Makefile below.
> >
> >
> > I fixed it up, and applied to linux-kbuild.
> > Thanks.
> >
> >
> > > I don't mind though.
> > >
> > > Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
> > >
> > > cheers
> > >
> > > > diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
> > > > index 6575bb0a0434..7492844a8b1b 100644
> > > > --- a/kernel/trace/Makefile
> > > > +++ b/kernel/trace/Makefile
> > > > @@ -2,9 +2,9 @@
> > > >
> > > >  # Do not instrument the tracer itself:
> > > >
> > > > +ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
> > > > +
> > > >  ifdef CONFIG_FUNCTION_TRACER
> > > > -ORIG_CFLAGS := $(KBUILD_CFLAGS)
> > > > -KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS))
> > > >
> > > >  # Avoid recursion due to instrumentation.
> > > >  KCSAN_SANITIZE := n
> >
> >
> >
> > --
> > Best Regards
> > Masahiro Yamada