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, I have 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-d...@arista.com/
[2]: https://lore.kernel.org/linux-doc/20190724170249.9644-1-d...@arista.com/
Signed-off-by: Dmitry Safonov
---
arch/x86/include/asm/kdebug.h | 3 ++-
arch/x86/kernel/dumpstack.c | 9 ---
arch/x86/kernel/process_32.c | 29 ++--
arch/x86/kernel/process_64.c | 51 ++-
4 files changed, 49 insertions(+), 43 deletions(-)
diff --git a/arch/x86/include/asm/kdebug.h b/arch/x86/include/asm/kdebug.h
index da024bbda6f4..d1514e70477b 100644
--- a/arch/x86/include/asm/kdebug.h
+++ b/arch/x86/include/asm/kdebug.h
@@ -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);
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index c36d629a25a8..ec90d71979f4 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(_summary_regs, SHOW_REGS_ALL);
+ __show_regs(_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)
{
+ int 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..
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index acfd6d2a0cbf..4f2f54e1281c 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -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:
