From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Dmitry Safonov <dima@arista.com>
Cc: linux-kernel@vger.kernel.org,
Dmitry Safonov <0x7f454c46@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Ingo Molnar <mingo@kernel.org>, Jiri Slaby <jslaby@suse.com>,
Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
clang-built-linux@googlegroups.com
Subject: Re: [PATCH 05/50] arm: Add loglvl to unwind_backtrace()
Date: Wed, 6 Nov 2019 09:12:59 +0000 [thread overview]
Message-ID: <20191106091258.GS25745@shell.armlinux.org.uk> (raw)
In-Reply-To: <20191106030542.868541-6-dima@arista.com>
On Wed, Nov 06, 2019 at 03:04:56AM +0000, Dmitry Safonov wrote:
> Currently, the log-level of show_stack() depends on a platform
> realization. It creates situations where the headers are printed with
> lower log level or higher than the stacktrace (depending on
> a platform or user).
>
> Furthermore, it forces the logic decision from user to an architecture
> side. In result, some users as sysrq/kdb/etc are doing tricks with
> temporary rising console_loglevel while printing their messages.
> And in result it not only may print unwanted messages from other CPUs,
> but also omit printing at all in the unlucky case where the printk()
> was deferred.
>
> Introducing log-level parameter and KERN_UNSUPPRESSED [1] seems
> an easier approach than introducing more printk buffers.
> Also, it will consolidate printings with headers.
>
> Add log level argument to unwind_backtrace() as a preparation for
> introducing show_stack_loglvl().
>
> As a good side-effect arm_syscall() is now printing errors with the same
> log level as the backtrace.
>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Will Deacon <will@kernel.org>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: clang-built-linux@googlegroups.com
> [1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u
> Signed-off-by: Dmitry Safonov <dima@arista.com>
> ---
> arch/arm/include/asm/unwind.h | 3 ++-
> arch/arm/kernel/traps.c | 6 +++---
> arch/arm/kernel/unwind.c | 7 ++++---
> 3 files changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm/include/asm/unwind.h b/arch/arm/include/asm/unwind.h
> index 6e282c33126b..0f8a3439902d 100644
> --- a/arch/arm/include/asm/unwind.h
> +++ b/arch/arm/include/asm/unwind.h
> @@ -36,7 +36,8 @@ extern struct unwind_table *unwind_table_add(unsigned long start,
> unsigned long text_addr,
> unsigned long text_size);
> extern void unwind_table_del(struct unwind_table *tab);
> -extern void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk);
> +extern void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk,
> + const char *loglvl);
>
> #endif /* !__ASSEMBLY__ */
>
> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
> index 7c3f32b26585..69e35462c9e9 100644
> --- a/arch/arm/kernel/traps.c
> +++ b/arch/arm/kernel/traps.c
> @@ -202,7 +202,7 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
> #ifdef CONFIG_ARM_UNWIND
> static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
> {
> - unwind_backtrace(regs, tsk);
> + unwind_backtrace(regs, tsk, KERN_DEBUG);
Why demote this to debug level? This is used as part of the kernel
panic message, surely we don't want this at debug level? What about
the non-unwind version?
> }
> #else
> static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
> @@ -660,10 +660,10 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
> if (user_debug & UDBG_SYSCALL) {
> pr_err("[%d] %s: arm syscall %d\n",
> task_pid_nr(current), current->comm, no);
> - dump_instr("", regs);
> + dump_instr(KERN_ERR, regs);
> if (user_mode(regs)) {
> __show_regs(regs);
> - c_backtrace(frame_pointer(regs), processor_mode(regs), NULL);
> + c_backtrace(frame_pointer(regs), processor_mode(regs), KERN_ERR);
> }
> }
> #endif
> diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
> index 0a65005e10f0..caaae1b6f721 100644
> --- a/arch/arm/kernel/unwind.c
> +++ b/arch/arm/kernel/unwind.c
> @@ -455,11 +455,12 @@ int unwind_frame(struct stackframe *frame)
> return URC_OK;
> }
>
> -void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk)
> +void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk,
> + const char *loglvl)
> {
> struct stackframe frame;
>
> - pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
> + printk("%s%s(regs = %p tsk = %p)\n", loglvl, __func__, regs, tsk);
Clearly, this isn't supposed to be part of the normal backtrace output...
Overall impression at this point is really not good.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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next prev parent reply other threads:[~2019-11-06 9:13 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20191106030542.868541-1-dima@arista.com>
2019-11-06 3:04 ` [PATCH 01/50] kallsyms/printk: Add loglvl to print_ip_sym() Dmitry Safonov
2019-11-06 4:38 ` Sergey Senozhatsky
2019-11-06 16:39 ` Dmitry Safonov
2019-11-13 15:49 ` Steven Rostedt
2019-11-06 3:04 ` [PATCH 02/50] alpha: Add show_stack_loglvl() Dmitry Safonov
2019-11-06 3:04 ` [PATCH 03/50] arc: " Dmitry Safonov
2019-11-06 3:04 ` [PATCH 04/50] arm/asm: Add loglvl to c_backtrace() Dmitry Safonov
2019-11-06 3:04 ` [PATCH 05/50] arm: Add loglvl to unwind_backtrace() Dmitry Safonov
2019-11-06 9:12 ` Russell King - ARM Linux admin [this message]
2019-11-06 16:32 ` Dmitry Safonov
2019-11-06 3:04 ` [PATCH 06/50] arm: Add loglvl to dump_backtrace() Dmitry Safonov
2019-11-06 3:04 ` [PATCH 07/50] arm: Wire up dump_backtrace_{entry,stm} Dmitry Safonov
2019-11-06 3:04 ` [PATCH 08/50] arm: Add show_stack_loglvl() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 09/50] arm64: Add loglvl to dump_backtrace() Dmitry Safonov
2019-11-06 13:25 ` Will Deacon
2019-11-06 16:00 ` Dmitry Safonov
2019-11-06 3:05 ` [PATCH 10/50] arm64: Add show_stack_loglvl() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 11/50] c6x: " Dmitry Safonov
2019-11-06 3:05 ` [PATCH 12/50] csky: " Dmitry Safonov
2019-11-06 3:05 ` [PATCH 13/50] h8300: " Dmitry Safonov
2019-11-06 3:05 ` [PATCH 14/50] hexagon: " Dmitry Safonov
2019-11-06 3:05 ` [PATCH 15/50] ia64: Pass log level as arg into ia64_do_show_stack() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 16/50] ia64: Add show_stack_loglvl() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 17/50] m68k: " Dmitry Safonov
2019-11-06 3:05 ` [PATCH 18/50] microblaze: Add loglvl to microblaze_unwind_inner() Dmitry Safonov
2019-11-07 8:59 ` Michal Simek
2019-11-08 7:52 ` kbuild test robot
2019-11-06 3:05 ` [PATCH 19/50] microblaze: Add loglvl to microblaze_unwind() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 20/50] microblaze: Add show_stack_loglvl() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 21/50] mips: " Dmitry Safonov
2019-11-06 3:05 ` [PATCH 22/50] nds32: " Dmitry Safonov
2019-11-06 3:05 ` [PATCH 23/50] nios2: " Dmitry Safonov
2019-11-06 3:05 ` [PATCH 24/50] openrisc: " Dmitry Safonov
2019-11-06 3:05 ` [PATCH 25/50] parisc: " Dmitry Safonov
2019-11-06 3:05 ` [PATCH 26/50] powerpc: " Dmitry Safonov
2019-11-06 9:52 ` Michael Ellerman
2019-11-06 16:01 ` Dmitry Safonov
2019-11-06 3:05 ` [PATCH 27/50] riscv: " Dmitry Safonov
2019-11-06 3:05 ` [PATCH 28/50] s390: " Dmitry Safonov
2019-11-06 3:05 ` [PATCH 29/50] sh: Add loglvl to dump_mem() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 30/50] sh: Remove needless printk() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 31/50] sh: Add loglvl to printk_address() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 32/50] sh: Add loglvl to show_trace() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 33/50] sh: Add show_stack_loglvl() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 34/50] sparc: " Dmitry Safonov
2019-11-06 3:33 ` David Miller
2019-11-06 16:02 ` Dmitry Safonov
2019-11-08 7:08 ` kbuild test robot
2019-11-06 3:05 ` [PATCH 35/50] um/sysrq: Remove needless variable sp Dmitry Safonov
2019-11-06 3:05 ` [PATCH 36/50] um: Add show_stack_loglvl() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 37/50] unicore32: Remove unused pmode argument in c_backtrace() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 38/50] unicore32: Add loglvl to c_backtrace() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 39/50] unicore32: Add show_stack_loglvl() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 40/50] x86: Add missing const qualifiers for log_lvl Dmitry Safonov
2019-11-06 3:05 ` [PATCH 41/50] x86: Add show_stack_loglvl() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 42/50] xtensa: Add loglvl to show_trace() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 43/50] xtensa: Add show_stack_loglvl() Dmitry Safonov
2019-11-06 4:13 ` Max Filippov
2019-11-06 8:15 ` Petr Mladek
2019-11-06 16:06 ` Dmitry Safonov
2019-11-06 16:44 ` Max Filippov
2019-11-06 3:05 ` [PATCH 44/50] sysrq: Use show_stack_loglvl() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 45/50] x86/amd_gart: Print stacktrace for a leak with KERN_ERR Dmitry Safonov
2019-11-06 3:05 ` [PATCH 46/50] power: Use show_stack_loglvl() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 47/50] kdb: Don't play with console_loglevel Dmitry Safonov
2019-11-06 3:05 ` [PATCH 48/50] sched: Print stack trace with KERN_INFO Dmitry Safonov
2019-11-06 3:05 ` [PATCH 49/50] kernel: Use show_stack_loglvl() Dmitry Safonov
2019-11-06 3:05 ` [PATCH 50/50] kernel: Rename show_stack_loglvl() => show_stack() Dmitry Safonov
2019-11-08 10:08 ` kbuild test robot
[not found] ` <20191106092039.GT4131@hirez.programming.kicks-ass.net>
[not found] ` <10db6fa1-5b17-ebe6-09e0-6335e09e4db8@arista.com>
[not found] ` <20191106203440.GH3079@worktop.programming.kicks-ass.net>
[not found] ` <20191106232512.GU25745@shell.armlinux.org.uk>
2019-11-07 7:27 ` [PATCH 00/50] Add log level to show_stack() Geert Uytterhoeven
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