Commit 44e21535 authored by Dmitry Safonov's avatar Dmitry Safonov Committed by Thomas Gleixner
Browse files

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: default avatarDmitry Safonov <dima@arista.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPetr Mladek <pmladek@suse.com>
Link: https://lkml.kernel.org/r/20200629144847.492794-3-dima@arista.com
parent fd07f802

arch/x86/include/asm/kdebug.h

+2 −1
Original line number Diff line number Diff line
@@ -36,7 +36,8 @@ extern void die(const char *, struct pt_regs *,long); 
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_regs(struct pt_regs *regs, enum show_regs_mode,

			const char *log_lvl);

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);

arch/x86/kernel/dumpstack.c

+6 −3
Original line number Diff line number Diff line
@@ -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..

arch/x86/kernel/process_32.c

+15 −14
Original line number Diff line number Diff line
@@ -56,7 +56,8 @@ 


#include "process.h"



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;

	unsigned long d0, d1, d2, d3, d6, d7;
@@ -67,14 +68,14 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) 
	else

		savesegment(gs, gs);



	show_ip(regs, KERN_DEFAULT);

	show_ip(regs, log_lvl);



	printk(KERN_DEFAULT "EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",

		regs->ax, regs->bx, regs->cx, regs->dx);

	printk(KERN_DEFAULT "ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",

		regs->si, regs->di, regs->bp, regs->sp);

	printk(KERN_DEFAULT "DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x EFLAGS: %08lx\n",

	       (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, regs->ss, regs->flags);

	printk("%sEAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",

		log_lvl, regs->ax, regs->bx, regs->cx, regs->dx);

	printk("%sESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",

		log_lvl, regs->si, regs->di, regs->bp, regs->sp);

	printk("%sDS: %04x ES: %04x FS: %04x GS: %04x SS: %04x EFLAGS: %08lx\n",

	       log_lvl, (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, regs->ss, regs->flags);



	if (mode != SHOW_REGS_ALL)

		return;
@@ -83,8 +84,8 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) 
	cr2 = read_cr2();

	cr3 = __read_cr3();

	cr4 = __read_cr4();

	printk(KERN_DEFAULT "CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",

			cr0, cr2, cr3, cr4);

	printk("%sCR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",

		log_lvl, cr0, cr2, cr3, cr4);



	get_debugreg(d0, 0);

	get_debugreg(d1, 1);
@@ -98,10 +99,10 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) 
	    (d6 == DR6_RESERVED) && (d7 == 0x400))

		return;



	printk(KERN_DEFAULT "DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",

			d0, d1, d2, d3);

	printk(KERN_DEFAULT "DR6: %08lx DR7: %08lx\n",

			d6, d7);

	printk("%sDR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",

		log_lvl, d0, d1, d2, d3);

	printk("%sDR6: %08lx DR7: %08lx\n",

		log_lvl, d6, d7);

}



void release_thread(struct task_struct *dead_task)

arch/x86/kernel/process_64.c

+26 −25
Original line number Diff line number Diff line
@@ -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)

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