From 44e215352cf17333992d56941b5bf4af60a67609 Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Mon, 29 Jun 2020 15:48:46 +0100 Subject: x86/dumpstack: Add log_lvl to __show_regs() show_trace_log_lvl() provides x86 platform-specific way to unwind backtrace with a given log level. Unfortunately, registers dump(s) are not printed with the same log level - instead, KERN_DEFAULT is always used. Arista's switches uses quite common setup with rsyslog, where only urgent messages goes to console (console_log_level=KERN_ERR), everything else goes into /var/log/ as the console baud-rate often is indecently slow (9600 bps). Backtrace dumps without registers printed have proven to be as useful as morning standups. Furthermore, in order to introduce KERN_UNSUPPRESSED (which I believe is still the most elegant way to fix raciness of sysrq[1]) the log level should be passed down the stack to register dumping functions. Besides, there is a potential use-case for printing traces with KERN_DEBUG level [2] (where registers dump shouldn't appear with higher log level). Add log_lvl parameter to __show_regs(). Keep the used log level intact to separate visible change. [1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/ [2]: https://lore.kernel.org/linux-doc/20190724170249.9644-1-dima@arista.com/ Signed-off-by: Dmitry Safonov Signed-off-by: Thomas Gleixner Acked-by: Petr Mladek Link: https://lkml.kernel.org/r/20200629144847.492794-3-dima@arista.com --- arch/x86/kernel/dumpstack.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'arch/x86/kernel/dumpstack.c') diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index c36d629a25a8..4954d6678cef 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -146,7 +146,7 @@ static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs, * they can be printed in the right context. */ if (!partial && on_stack(info, regs, sizeof(*regs))) { - __show_regs(regs, SHOW_REGS_SHORT); + __show_regs(regs, SHOW_REGS_SHORT, KERN_DEFAULT); } else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET, IRET_FRAME_SIZE)) { @@ -345,7 +345,7 @@ void oops_end(unsigned long flags, struct pt_regs *regs, int signr) oops_exit(); /* Executive summary in case the oops scrolled away */ - __show_regs(&exec_summary_regs, SHOW_REGS_ALL); + __show_regs(&exec_summary_regs, SHOW_REGS_ALL, KERN_DEFAULT); if (!signr) return; @@ -437,9 +437,12 @@ void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr) void show_regs(struct pt_regs *regs) { + enum show_regs_mode print_kernel_regs; + show_regs_print_info(KERN_DEFAULT); - __show_regs(regs, user_mode(regs) ? SHOW_REGS_USER : SHOW_REGS_ALL); + print_kernel_regs = user_mode(regs) ? SHOW_REGS_USER : SHOW_REGS_ALL; + __show_regs(regs, print_kernel_regs, KERN_DEFAULT); /* * When in-kernel, we also print out the stack at the time of the fault.. -- cgit v1.2.3