From: Palmer Dabbelt <palmerdabbelt@google.com>
To: guoren@kernel.org
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
anup@brainfault.org, greentime.hu@sifive.com, zong.li@sifive.com,
me@packi.ch, Bjorn Topel <bjorn.topel@gmail.com>,
Atish Patra <Atish.Patra@wdc.com>,
penberg@kernel.org, mhiramat@kernel.org,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
linux-csky@vger.kernel.org, guoren@kernel.org,
guoren@linux.alibaba.com, vincent.chen@sifive.com,
alankao@andestech.com, green.hu@gmail.com
Subject: Re: [PATCH v2 1/6] riscv: Fixup __vdso_gettimeofday broke dynamic ftrace
Date: Mon, 20 Jul 2020 18:10:56 -0700 (PDT) [thread overview]
Message-ID: <mhng-43aa4e60-5754-4bfd-9502-7b0efe369c79@palmerdabbelt-glaptop1> (raw)
In-Reply-To: <1594261154-69745-2-git-send-email-guoren@kernel.org>
On Wed, 08 Jul 2020 19:19:09 PDT (-0700), guoren@kernel.org wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
>
> For linux-5.8-rc1, enable ftrace of riscv will cause boot panic:
>
> [ 2.388980] Run /sbin/init as init process
> [ 2.529938] init[39]: unhandled signal 4 code 0x1 at 0x0000003ff449e000
> [ 2.531078] CPU: 0 PID: 39 Comm: init Not tainted 5.8.0-rc1-dirty #13
> [ 2.532719] epc: 0000003ff449e000 ra : 0000003ff449e954 sp : 0000003fffedb900
> [ 2.534005] gp : 00000000000e8528 tp : 0000003ff449d800 t0 : 000000000000001e
> [ 2.534965] t1 : 000000000000000a t2 : 0000003fffedb89e s0 : 0000003fffedb920
> [ 2.536279] s1 : 0000003fffedb940 a0 : 0000003ff43d4b2c a1 : 0000000000000000
> [ 2.537334] a2 : 0000000000000001 a3 : 0000000000000000 a4 : fffffffffbad8000
> [ 2.538466] a5 : 0000003ff449e93a a6 : 0000000000000000 a7 : 0000000000000000
> [ 2.539511] s2 : 0000000000000000 s3 : 0000003ff448412c s4 : 0000000000000010
> [ 2.541260] s5 : 0000000000000016 s6 : 00000000000d0a30 s7 : 0000003fffedba70
> [ 2.542152] s8 : 0000000000000000 s9 : 0000000000000000 s10: 0000003fffedb960
> [ 2.543335] s11: 0000000000000000 t3 : 0000000000000000 t4 : 0000003fffedb8a0
> [ 2.544471] t5 : 0000000000000000 t6 : 0000000000000000
> [ 2.545730] status: 0000000000004020 badaddr: 00000000464c457f cause: 0000000000000002
> [ 2.549867] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004
> [ 2.551267] CPU: 0 PID: 1 Comm: init Not tainted 5.8.0-rc1-dirty #13
> [ 2.552061] Call Trace:
> [ 2.552626] [<ffffffe00020374a>] walk_stackframe+0x0/0xc4
> [ 2.553486] [<ffffffe0002039f4>] show_stack+0x40/0x4c
> [ 2.553995] [<ffffffe00054a6ae>] dump_stack+0x7a/0x98
> [ 2.554615] [<ffffffe00020b9b8>] panic+0x114/0x2f4
> [ 2.555395] [<ffffffe00020ebd6>] do_exit+0x89c/0x8c2
> [ 2.555949] [<ffffffe00020f930>] do_group_exit+0x3a/0x90
> [ 2.556715] [<ffffffe000219e08>] get_signal+0xe2/0x6e6
> [ 2.557388] [<ffffffe000202d72>] do_notify_resume+0x6a/0x37a
> [ 2.558089] [<ffffffe000201c16>] ret_from_exception+0x0/0xc
>
> "ra:0x3ff449e954" is the return address of "call _mcount" in the
> prologue of __vdso_gettimeofday(). Without proper relocate, pc jmp
> to 0x0000003ff449e000 (vdso map base) with a illegal instruction
> trap.
>
> The solution comes from arch/arm64/kernel/vdso/Makefile:
>
> CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS)
>
> - CC_FLAGS_SCS is ShadowCallStack feature in Clang and only
> implemented for arm64, no use for riscv.
>
> The bug comes from the following commit:
>
> ad5d1122b82f ("riscv: use vDSO common flow to reduce the latency of the time-related functions")
>
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Reviewed-by: Pekka Enberg <penberg@kernel.org>
> Cc: Vincent Chen <vincent.chen@sifive.com>
> Cc: Atish Patra <atish.patra@wdc.com>
> Cc: Palmer Dabbelt <palmerdabbelt@google.com>
> Cc: Alan Kao <alankao@andestech.com>
> Cc: Greentime Hu <green.hu@gmail.com>
> ---
> arch/riscv/kernel/vdso/Makefile | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile
> index 38ba55b..3079935 100644
> --- a/arch/riscv/kernel/vdso/Makefile
> +++ b/arch/riscv/kernel/vdso/Makefile
> @@ -27,6 +27,9 @@ obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
> obj-y += vdso.o vdso-syms.o
> CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
>
> +# Disable -pg to prevent insert call site
> +CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os
> +
> # Disable gcov profiling for VDSO code
> GCOV_PROFILE := n
As far as I can tell this is already in Linus' tree. LMK if I'm missing
something.
next prev parent reply other threads:[~2020-07-21 1:10 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-09 2:19 [PATCH v2 0/6] riscv: Add k/uprobe supported guoren
2020-07-09 2:19 ` [PATCH v2 1/6] riscv: Fixup __vdso_gettimeofday broke dynamic ftrace guoren
2020-07-21 1:10 ` Palmer Dabbelt [this message]
2020-07-09 2:19 ` [PATCH v2 2/6] RISC-V: Implement ptrace regs and stack API guoren
2020-07-09 2:19 ` [PATCH v2 3/6] riscv: Fixup compile error BUILD_BUG_ON failed guoren
2020-07-09 2:19 ` [PATCH v2 4/6] riscv: Add kprobes supported guoren
2020-07-09 2:19 ` [PATCH v2 5/6] riscv: Add uprobes supported guoren
2020-07-09 2:19 ` [PATCH v2 6/6] riscv: Add KPROBES_ON_FTRACE supported guoren
2020-07-10 13:50 ` Masami Hiramatsu
2020-07-11 1:32 ` Guo Ren
2020-07-12 13:37 ` Masami Hiramatsu
2020-07-13 23:47 ` Guo Ren
2020-07-14 11:32 ` Masami Hiramatsu
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