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/process_64.c | 51 ++++++++++++++++++++++---------------------- 1 file changed, 26 insertions(+), 25 deletions(-) (limited to 'arch/x86/kernel/process_64.c') diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 09bcb296cda6..04d201ad3a1e 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -62,30 +62,31 @@ #include "process.h" /* Prints also some state that isn't saved in the pt_regs */ -void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) +void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, + const char *log_lvl) { unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs; unsigned long d0, d1, d2, d3, d6, d7; unsigned int fsindex, gsindex; unsigned int ds, es; - show_iret_regs(regs, KERN_DEFAULT); + show_iret_regs(regs, log_lvl); if (regs->orig_ax != -1) pr_cont(" ORIG_RAX: %016lx\n", regs->orig_ax); else pr_cont("\n"); - printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n", - regs->ax, regs->bx, regs->cx); - printk(KERN_DEFAULT "RDX: %016lx RSI: %016lx RDI: %016lx\n", - regs->dx, regs->si, regs->di); - printk(KERN_DEFAULT "RBP: %016lx R08: %016lx R09: %016lx\n", - regs->bp, regs->r8, regs->r9); - printk(KERN_DEFAULT "R10: %016lx R11: %016lx R12: %016lx\n", - regs->r10, regs->r11, regs->r12); - printk(KERN_DEFAULT "R13: %016lx R14: %016lx R15: %016lx\n", - regs->r13, regs->r14, regs->r15); + printk("%sRAX: %016lx RBX: %016lx RCX: %016lx\n", + log_lvl, regs->ax, regs->bx, regs->cx); + printk("%sRDX: %016lx RSI: %016lx RDI: %016lx\n", + log_lvl, regs->dx, regs->si, regs->di); + printk("%sRBP: %016lx R08: %016lx R09: %016lx\n", + log_lvl, regs->bp, regs->r8, regs->r9); + printk("%sR10: %016lx R11: %016lx R12: %016lx\n", + log_lvl, regs->r10, regs->r11, regs->r12); + printk("%sR13: %016lx R14: %016lx R15: %016lx\n", + log_lvl, regs->r13, regs->r14, regs->r15); if (mode == SHOW_REGS_SHORT) return; @@ -93,8 +94,8 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) if (mode == SHOW_REGS_USER) { rdmsrl(MSR_FS_BASE, fs); rdmsrl(MSR_KERNEL_GS_BASE, shadowgs); - printk(KERN_DEFAULT "FS: %016lx GS: %016lx\n", - fs, shadowgs); + printk("%sFS: %016lx GS: %016lx\n", + log_lvl, fs, shadowgs); return; } @@ -112,12 +113,12 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) cr3 = __read_cr3(); cr4 = __read_cr4(); - printk(KERN_DEFAULT "FS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n", - fs, fsindex, gs, gsindex, shadowgs); - printk(KERN_DEFAULT "CS: %04lx DS: %04x ES: %04x CR0: %016lx\n", regs->cs, ds, - es, cr0); - printk(KERN_DEFAULT "CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3, - cr4); + printk("%sFS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n", + log_lvl, fs, fsindex, gs, gsindex, shadowgs); + printk("%sCS: %04lx DS: %04x ES: %04x CR0: %016lx\n", + log_lvl, regs->cs, ds, es, cr0); + printk("%sCR2: %016lx CR3: %016lx CR4: %016lx\n", + log_lvl, cr2, cr3, cr4); get_debugreg(d0, 0); get_debugreg(d1, 1); @@ -129,14 +130,14 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) /* Only print out debug registers if they are in their non-default state. */ if (!((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && (d6 == DR6_RESERVED) && (d7 == 0x400))) { - printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n", - d0, d1, d2); - printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n", - d3, d6, d7); + printk("%sDR0: %016lx DR1: %016lx DR2: %016lx\n", + log_lvl, d0, d1, d2); + printk("%sDR3: %016lx DR6: %016lx DR7: %016lx\n", + log_lvl, d3, d6, d7); } if (boot_cpu_has(X86_FEATURE_OSPKE)) - printk(KERN_DEFAULT "PKRU: %08x\n", read_pkru()); + printk("%sPKRU: %08x\n", log_lvl, read_pkru()); } void release_thread(struct task_struct *dead_task) -- cgit v1.2.3