From fd07f802a70935fbbfb9cc2d11e1d8ac95f28e44 Mon Sep 17 00:00:00 2001 From: Dmitry Safonov <dima@arista.com> Date: Mon, 29 Jun 2020 15:48:45 +0100 Subject: [PATCH] x86/dumpstack: Add log_lvl to show_iret_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_iret_regs() as a preparation to add it to __show_regs() and show_regs_if_on_stack(). [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 <dima@arista.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Petr Mladek <pmladek@suse.com> Link: https://lkml.kernel.org/r/20200629144847.492794-2-dima@arista.com --- arch/x86/include/asm/kdebug.h | 2 +- arch/x86/kernel/dumpstack.c | 8 ++++---- arch/x86/kernel/process_64.c | 2 +- 3 files changed, 6 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/kdebug.h b/arch/x86/include/asm/kdebug.h index 247ab14c6309..da024bbda6f4 100644 --- a/arch/x86/include/asm/kdebug.h +++ b/arch/x86/include/asm/kdebug.h @@ -37,7 +37,7 @@ void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr); extern int __must_check __die(const char *, struct pt_regs *, long); extern void show_stack_regs(struct pt_regs *regs); extern void __show_regs(struct pt_regs *regs, enum show_regs_mode); -extern void show_iret_regs(struct pt_regs *regs); +extern void show_iret_regs(struct pt_regs *regs, const char *log_lvl); extern unsigned long oops_begin(void); extern void oops_end(unsigned long, struct pt_regs *, int signr); diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index b037cfa7c0c5..c36d629a25a8 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -126,10 +126,10 @@ void show_ip(struct pt_regs *regs, const char *loglvl) show_opcodes(regs, loglvl); } -void show_iret_regs(struct pt_regs *regs) +void show_iret_regs(struct pt_regs *regs, const char *log_lvl) { - show_ip(regs, KERN_DEFAULT); - printk(KERN_DEFAULT "RSP: %04x:%016lx EFLAGS: %08lx", (int)regs->ss, + show_ip(regs, log_lvl); + printk("%sRSP: %04x:%016lx EFLAGS: %08lx", log_lvl, (int)regs->ss, regs->sp, regs->flags); } @@ -155,7 +155,7 @@ static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs, * full pt_regs might not have been saved yet. In that case * just print the iret frame. */ - show_iret_regs(regs); + show_iret_regs(regs, KERN_DEFAULT); } } diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 9a97415b2139..09bcb296cda6 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -69,7 +69,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) unsigned int fsindex, gsindex; unsigned int ds, es; - show_iret_regs(regs); + show_iret_regs(regs, KERN_DEFAULT); if (regs->orig_ax != -1) pr_cont(" ORIG_RAX: %016lx\n", regs->orig_ax);