* [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace
@ 2020-06-23 16:29 Dmitry Safonov
2020-06-23 16:29 ` [PATCH 1/3] x86/dumpstack: Add log_lvl to show_iret_regs() Dmitry Safonov
` (3 more replies)
0 siblings, 4 replies; 8+ messages in thread
From: Dmitry Safonov @ 2020-06-23 16:29 UTC (permalink / raw)
To: linux-kernel
Cc: Dmitry Safonov, Dmitry Safonov, Andy Lutomirski, Borislav Petkov,
H. Peter Anvin, Ingo Molnar, Jann Horn, Petr Mladek,
Sergey Senozhatsky, Steven Rostedt, Tetsuo Handa,
Thomas Gleixner, x86
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 than the backtrace).
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
[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/
Dmitry Safonov (3):
x86/dumpstack: Add log_lvl to show_iret_regs()
x86/dumpstack: Add log_lvl to __show_regs()
x86/dumpstack: Show registers dump with trace's log level
arch/x86/include/asm/kdebug.h | 5 ++--
arch/x86/kernel/dumpstack.c | 23 +++++++++-------
arch/x86/kernel/process_32.c | 29 ++++++++++----------
arch/x86/kernel/process_64.c | 51 ++++++++++++++++++-----------------
4 files changed, 57 insertions(+), 51 deletions(-)
--
2.27.0
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH 1/3] x86/dumpstack: Add log_lvl to show_iret_regs()
2020-06-23 16:29 [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace Dmitry Safonov
@ 2020-06-23 16:29 ` Dmitry Safonov
2020-06-23 16:29 ` [PATCH 2/3] x86/dumpstack: Add log_lvl to __show_regs() Dmitry Safonov
` (2 subsequent siblings)
3 siblings, 0 replies; 8+ messages in thread
From: Dmitry Safonov @ 2020-06-23 16:29 UTC (permalink / raw)
To: linux-kernel
Cc: Dmitry Safonov, Dmitry Safonov, Andy Lutomirski, Borislav Petkov,
H. Peter Anvin, Ingo Molnar, Jann Horn, Petr Mladek,
Sergey Senozhatsky, Steven Rostedt, Tetsuo Handa,
Thomas Gleixner, x86
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_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>
---
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);
--
2.27.0
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH 2/3] x86/dumpstack: Add log_lvl to __show_regs()
2020-06-23 16:29 [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace Dmitry Safonov
2020-06-23 16:29 ` [PATCH 1/3] x86/dumpstack: Add log_lvl to show_iret_regs() Dmitry Safonov
@ 2020-06-23 16:29 ` Dmitry Safonov
2020-06-23 16:45 ` Jann Horn
2020-06-23 16:29 ` [PATCH 3/3] x86/dumpstack: Show registers dump with trace's log level Dmitry Safonov
2020-06-24 6:50 ` [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace Petr Mladek
3 siblings, 1 reply; 8+ messages in thread
From: Dmitry Safonov @ 2020-06-23 16:29 UTC (permalink / raw)
To: linux-kernel
Cc: Dmitry Safonov, Dmitry Safonov, Andy Lutomirski, Borislav Petkov,
H. Peter Anvin, Ingo Molnar, Jann Horn, Petr Mladek,
Sergey Senozhatsky, Steven Rostedt, Tetsuo Handa,
Thomas Gleixner, x86
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-dima@arista.com/
[2]: https://lore.kernel.org/linux-doc/20190724170249.9644-1-dima@arista.com/
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
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(&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)
{
+ 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: %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)
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)
--
2.27.0
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH 3/3] x86/dumpstack: Show registers dump with trace's log level
2020-06-23 16:29 [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace Dmitry Safonov
2020-06-23 16:29 ` [PATCH 1/3] x86/dumpstack: Add log_lvl to show_iret_regs() Dmitry Safonov
2020-06-23 16:29 ` [PATCH 2/3] x86/dumpstack: Add log_lvl to __show_regs() Dmitry Safonov
@ 2020-06-23 16:29 ` Dmitry Safonov
2020-06-24 6:50 ` [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace Petr Mladek
3 siblings, 0 replies; 8+ messages in thread
From: Dmitry Safonov @ 2020-06-23 16:29 UTC (permalink / raw)
To: linux-kernel
Cc: Dmitry Safonov, Dmitry Safonov, Andy Lutomirski, Borislav Petkov,
H. Peter Anvin, Ingo Molnar, Jann Horn, Petr Mladek,
Sergey Senozhatsky, Steven Rostedt, Tetsuo Handa,
Thomas Gleixner, x86
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).
After all preparations are done, provide log_lvl parameter for
show_regs_if_on_stack() and wire up to actual log level used as
an argument for show_trace_log_lvl().
[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>
---
arch/x86/kernel/dumpstack.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index ec90d71979f4..6b00964d5873 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -134,7 +134,7 @@ void show_iret_regs(struct pt_regs *regs, const char *log_lvl)
}
static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs,
- bool partial)
+ bool partial, const char *log_lvl)
{
/*
* These on_stack() checks aren't strictly necessary: the unwind code
@@ -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, KERN_DEFAULT);
+ __show_regs(regs, SHOW_REGS_SHORT, log_lvl);
} else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET,
IRET_FRAME_SIZE)) {
@@ -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, KERN_DEFAULT);
+ show_iret_regs(regs, log_lvl);
}
}
@@ -210,7 +210,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
printk("%s <%s>\n", log_lvl, stack_name);
if (regs)
- show_regs_if_on_stack(&stack_info, regs, partial);
+ show_regs_if_on_stack(&stack_info, regs, partial, log_lvl);
/*
* Scan the stack, printing any text addresses we find. At the
@@ -271,7 +271,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
/* if the frame has entry regs, print them */
regs = unwind_get_entry_regs(&state, &partial);
if (regs)
- show_regs_if_on_stack(&stack_info, regs, partial);
+ show_regs_if_on_stack(&stack_info, regs, partial, log_lvl);
}
if (stack_name)
--
2.27.0
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 2/3] x86/dumpstack: Add log_lvl to __show_regs()
2020-06-23 16:29 ` [PATCH 2/3] x86/dumpstack: Add log_lvl to __show_regs() Dmitry Safonov
@ 2020-06-23 16:45 ` Jann Horn
2020-06-25 16:42 ` Dmitry Safonov
0 siblings, 1 reply; 8+ messages in thread
From: Jann Horn @ 2020-06-23 16:45 UTC (permalink / raw)
To: Dmitry Safonov
Cc: kernel list, Dmitry Safonov, Andy Lutomirski, Borislav Petkov,
H. Peter Anvin, Ingo Molnar, Petr Mladek, Sergey Senozhatsky,
Steven Rostedt, Tetsuo Handa, Thomas Gleixner,
the arch/x86 maintainers
On Tue, Jun 23, 2020 at 6:30 PM Dmitry Safonov <dima@arista.com> wrote:
> 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.
This change seems like a good idea to me; just one small nit:
[...]
> 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);
print_kernel_regs should probably have type "enum show_regs_mode"?
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace
2020-06-23 16:29 [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace Dmitry Safonov
` (2 preceding siblings ...)
2020-06-23 16:29 ` [PATCH 3/3] x86/dumpstack: Show registers dump with trace's log level Dmitry Safonov
@ 2020-06-24 6:50 ` Petr Mladek
2020-06-25 16:41 ` Dmitry Safonov
3 siblings, 1 reply; 8+ messages in thread
From: Petr Mladek @ 2020-06-24 6:50 UTC (permalink / raw)
To: Dmitry Safonov
Cc: linux-kernel, Dmitry Safonov, Andy Lutomirski, Borislav Petkov,
H. Peter Anvin, Ingo Molnar, Jann Horn, Sergey Senozhatsky,
Steven Rostedt, Tetsuo Handa, Thomas Gleixner, x86
On Tue 2020-06-23 17:29:55, Dmitry Safonov wrote:
> 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 than the backtrace).
>
> Dmitry Safonov (3):
> x86/dumpstack: Add log_lvl to show_iret_regs()
> x86/dumpstack: Add log_lvl to __show_regs()
> x86/dumpstack: Show registers dump with trace's log level
The change makes sense. It is natural next step after adding log_lvl
parameter for printing stack traces. For the entire patchset:
Acked-by: Petr Mladek <pmladek@suse.com>
Are there any plans to add this also for other architectures, please?
Best Regards,
Petr
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace
2020-06-24 6:50 ` [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace Petr Mladek
@ 2020-06-25 16:41 ` Dmitry Safonov
0 siblings, 0 replies; 8+ messages in thread
From: Dmitry Safonov @ 2020-06-25 16:41 UTC (permalink / raw)
To: Petr Mladek
Cc: linux-kernel, Dmitry Safonov, Andy Lutomirski, Borislav Petkov,
H. Peter Anvin, Ingo Molnar, Jann Horn, Sergey Senozhatsky,
Steven Rostedt, Tetsuo Handa, Thomas Gleixner, x86
On 6/24/20 7:50 AM, Petr Mladek wrote:
> On Tue 2020-06-23 17:29:55, Dmitry Safonov wrote:
>> 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 than the backtrace).
>>
>> Dmitry Safonov (3):
>> x86/dumpstack: Add log_lvl to show_iret_regs()
>> x86/dumpstack: Add log_lvl to __show_regs()
>> x86/dumpstack: Show registers dump with trace's log level
>
> The change makes sense. It is natural next step after adding log_lvl
> parameter for printing stack traces. For the entire patchset:
>
> Acked-by: Petr Mladek <pmladek@suse.com>
I'll address the nit by Jann and resend v2 with your Ack, thanks!
> Are there any plans to add this also for other architectures, please?
Yes, I'll look into that.
Thanks,
Dmitry
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/3] x86/dumpstack: Add log_lvl to __show_regs()
2020-06-23 16:45 ` Jann Horn
@ 2020-06-25 16:42 ` Dmitry Safonov
0 siblings, 0 replies; 8+ messages in thread
From: Dmitry Safonov @ 2020-06-25 16:42 UTC (permalink / raw)
To: Jann Horn
Cc: kernel list, Dmitry Safonov, Andy Lutomirski, Borislav Petkov,
H. Peter Anvin, Ingo Molnar, Petr Mladek, Sergey Senozhatsky,
Steven Rostedt, Tetsuo Handa, Thomas Gleixner,
the arch/x86 maintainers
On 6/23/20 5:45 PM, Jann Horn wrote:
> On Tue, Jun 23, 2020 at 6:30 PM Dmitry Safonov <dima@arista.com> wrote:
>> 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.
>
> This change seems like a good idea to me; just one small nit:
>
> [...]
>> 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);
>
> print_kernel_regs should probably have type "enum show_regs_mode"?
Makes sense, will fix in v2.
Thanks,
Dmitry
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2020-06-25 16:42 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-23 16:29 [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace Dmitry Safonov
2020-06-23 16:29 ` [PATCH 1/3] x86/dumpstack: Add log_lvl to show_iret_regs() Dmitry Safonov
2020-06-23 16:29 ` [PATCH 2/3] x86/dumpstack: Add log_lvl to __show_regs() Dmitry Safonov
2020-06-23 16:45 ` Jann Horn
2020-06-25 16:42 ` Dmitry Safonov
2020-06-23 16:29 ` [PATCH 3/3] x86/dumpstack: Show registers dump with trace's log level Dmitry Safonov
2020-06-24 6:50 ` [PATCH 0/3] x86/dumpstack: Print registers with the same log level as the backtrace Petr Mladek
2020-06-25 16:41 ` Dmitry Safonov
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