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* [PATCH] powerpc/xmon: Change printk() to pr_cont()
@ 2020-12-04 10:35 Christophe Leroy
  2020-12-04 10:56 ` Michael Ellerman
  2020-12-10 11:29 ` Michael Ellerman
  0 siblings, 2 replies; 4+ messages in thread
From: Christophe Leroy @ 2020-12-04 10:35 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman
  Cc: linux-kernel, linuxppc-dev

Since some time now, printk() adds carriage return, leading to
unusable xmon output:

[   54.288722] sysrq: Entering xmon
[   54.292209] Vector: 0  at [cace3d2c]
[   54.292274]     pc:
[   54.292331] c0023650
[   54.292468] : xmon+0x28/0x58
[   54.292519]
[   54.292574]     lr:
[   54.292630] c0023724
[   54.292749] : sysrq_handle_xmon+0xa4/0xfc
[   54.292801]
[   54.292867]     sp: cace3de8
[   54.292931]    msr: 9032
[   54.292999]   current = 0xc28d0000
[   54.293072]     pid   = 377, comm = sh
[   54.293157] Linux version 5.10.0-rc6-s3k-dev-01364-gedf13f0ccd76-dirty (root@po17688vm.idsi0.si.c-s.fr) (powerpc64-linux-gcc (GCC) 10.1.0, GNU ld (GNU Binutils) 2.34) #4211 PREEMPT Fri Dec 4 09:32:11 UTC 2020
[   54.293287] enter ? for help
[   54.293470] [cace3de8]
[   54.293532] c0023724
[   54.293654]  sysrq_handle_xmon+0xa4/0xfc
[   54.293711]  (unreliable)
[   54.293859] [cace3e18]
[   54.293918] c03885a8
[   54.294056]  __handle_sysrq+0xe4/0x1d4
[   54.294108]
[   54.294255] [cace3e48]
[   54.294314] c0388704
[   54.294441]  write_sysrq_trigger+0x34/0x74
[   54.294493]
[   54.294641] [cace3e68]
[   54.294700] c01f65d0
[   54.294822]  proc_reg_write+0xac/0x11c
[   54.294875]
[   54.295023] [cace3e88]
[   54.295082] c0179910
[   54.295198]  vfs_write+0x134/0x46c
[   54.295250]
[   54.295396] [cace3f08]
[   54.295455] c0179de8
[   54.295567]  ksys_write+0x78/0x11c
[   54.295619]
[   54.295766] [cace3f38]
[   54.295825] c00110d0
[   54.295951]  ret_from_syscall+0x0/0x34
[   54.296002]
[   54.296159] --- Exception: c01 (System Call) at
[   54.296217] 0fd4e784
[   54.296303]
[   54.296375] SP (7fca6ff0) is in userspace
[   54.296431] mon>
[   54.296484]  <no input ...>

Use pr_cont() instead.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Fixes: 4bcc595ccd80 ("printk: reinstate KERN_CONT for printing continuation lines")
Cc: stable@vger.kernel.org
---
 arch/powerpc/xmon/nonstdio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/xmon/nonstdio.c b/arch/powerpc/xmon/nonstdio.c
index 5c1a50912229..9b0d85bff021 100644
--- a/arch/powerpc/xmon/nonstdio.c
+++ b/arch/powerpc/xmon/nonstdio.c
@@ -178,7 +178,7 @@ void xmon_printf(const char *format, ...)
 
 	if (n && rc == 0) {
 		/* No udbg hooks, fallback to printk() - dangerous */
-		printk("%s", xmon_outbuf);
+		pr_cont("%s", xmon_outbuf);
 	}
 }
 
-- 
2.25.0


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/xmon: Change printk() to pr_cont()
  2020-12-04 10:35 [PATCH] powerpc/xmon: Change printk() to pr_cont() Christophe Leroy
@ 2020-12-04 10:56 ` Michael Ellerman
  2020-12-04 15:55   ` Joe Perches
  2020-12-10 11:29 ` Michael Ellerman
  1 sibling, 1 reply; 4+ messages in thread
From: Michael Ellerman @ 2020-12-04 10:56 UTC (permalink / raw)
  To: Christophe Leroy, Benjamin Herrenschmidt, Paul Mackerras
  Cc: linux-kernel, linuxppc-dev

Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> Since some time now, printk() adds carriage return, leading to
> unusable xmon output:
>
> [   54.288722] sysrq: Entering xmon
> [   54.292209] Vector: 0  at [cace3d2c]
> [   54.292274]     pc:
> [   54.292331] c0023650

...

> diff --git a/arch/powerpc/xmon/nonstdio.c b/arch/powerpc/xmon/nonstdio.c
> index 5c1a50912229..9b0d85bff021 100644
> --- a/arch/powerpc/xmon/nonstdio.c
> +++ b/arch/powerpc/xmon/nonstdio.c
> @@ -178,7 +178,7 @@ void xmon_printf(const char *format, ...)
>  
>  	if (n && rc == 0) {
>  		/* No udbg hooks, fallback to printk() - dangerous */
> -		printk("%s", xmon_outbuf);
> +		pr_cont("%s", xmon_outbuf);
>  	}

Ah OK, in the case where there's no udbg backend. We basically always
have a udbg backend on 64-bit, via hvc console. Which explains why we
haven't noticed it.

Will pick up the patch.

cheers

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/xmon: Change printk() to pr_cont()
  2020-12-04 10:56 ` Michael Ellerman
@ 2020-12-04 15:55   ` Joe Perches
  0 siblings, 0 replies; 4+ messages in thread
From: Joe Perches @ 2020-12-04 15:55 UTC (permalink / raw)
  To: Michael Ellerman, Christophe Leroy, Benjamin Herrenschmidt,
	Paul Mackerras
  Cc: linux-kernel, linuxppc-dev

On Fri, 2020-12-04 at 21:56 +1100, Michael Ellerman wrote:
> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> > Since some time now, printk() adds carriage return, leading to
> > unusable xmon output:
> > 
> > [   54.288722] sysrq: Entering xmon
> > [   54.292209] Vector: 0  at [cace3d2c]
> > [   54.292274]     pc:
> > [   54.292331] c0023650
> 
> ...
> 
> > diff --git a/arch/powerpc/xmon/nonstdio.c b/arch/powerpc/xmon/nonstdio.c
> > index 5c1a50912229..9b0d85bff021 100644
> > --- a/arch/powerpc/xmon/nonstdio.c
> > +++ b/arch/powerpc/xmon/nonstdio.c
> > @@ -178,7 +178,7 @@ void xmon_printf(const char *format, ...)
> >  
> > 
> >  	if (n && rc == 0) {
> >  		/* No udbg hooks, fallback to printk() - dangerous */
> > -		printk("%s", xmon_outbuf);
> > +		pr_cont("%s", xmon_outbuf);
> >  	}
> 
> Ah OK, in the case where there's no udbg backend. We basically always
> have a udbg backend on 64-bit, via hvc console. Which explains why we
> haven't noticed it.
> 
> Will pick up the patch.
> 
> cheers

Perhaps all of these bare printks should be inspected for defects:

$ git grep -P -n '\bprintk\s*\(\s*(?!KERN_\w+)"[^\\n]*"' arch/powerpc
arch/powerpc/kernel/process.c:1475:     printk("NIP:  "REG" LR: "REG" CTR: "REG"\n",
arch/powerpc/kernel/process.c:1479:     printk("MSR:  "REG" ", regs->msr);
arch/powerpc/kernel/process.c:1513:             printk("NIP ["REG"] %pS\n", regs->nip, (void *)regs->nip);
arch/powerpc/kernel/process.c:1514:             printk("LR ["REG"] %pS\n", regs->link, (void *)regs->link);
arch/powerpc/kernel/process.c:2157:                     printk("%s["REG"] ["REG"] %pS",
arch/powerpc/kernel/traps.c:621:        printk("Caused by (from MCSR=%lx): ", reason);
arch/powerpc/kernel/traps.c:726:        printk("Caused by (from MCSR=%lx): ", reason);
arch/powerpc/kernel/traps.c:766:        printk("Caused by (from MCSR=%lx): ", reason);
arch/powerpc/kernel/traps.c:791:        printk("Caused by (from SRR1=%lx): ", reason);
arch/powerpc/kernel/udbg.c:95:          printk("%s", s);
arch/powerpc/math-emu/fabs.c:13:        printk("%s: D %p, B %p: ", __func__, frD, frB);
arch/powerpc/math-emu/fctiw.c:22:       printk("%s: D %p, B %p: ", __func__, frD, frB);
arch/powerpc/math-emu/fctiwz.c:29:      printk("%s: D %p, B %p: ", __func__, frD, frB);
arch/powerpc/math-emu/fmr.c:13: printk("%s: D %p, B %p: ", __func__, frD, frB);
arch/powerpc/math-emu/fnabs.c:13:       printk("%s: D %p, B %p: ", __func__, frD, frB);
arch/powerpc/math-emu/fneg.c:13:        printk("%s: D %p, B %p: ", __func__, frD, frB);
arch/powerpc/math-emu/lfd.c:15: printk("%s: D %p, ea %p: ", __func__, frD, ea);
arch/powerpc/math-emu/stfd.c:11:        printk("%s: S %p, ea %p: ", __func__, frS, ea);
arch/powerpc/mm/nohash/44x.c:192:                                       printk("%d ", i);
arch/powerpc/platforms/4xx/machine_check.c:19:          printk("Data");
arch/powerpc/platforms/chrp/pci.c:256:                  printk(" at %llx", (unsigned long long)r.start);
arch/powerpc/platforms/embedded6xx/ls_uart.c:47:                                        printk("%c", in_8(avr_addr + UART_RX));
arch/powerpc/platforms/powermac/pfunc_core.c:83:        printk("%s", title);
arch/powerpc/platforms/powermac/pfunc_core.c:85:                printk("%02x ", *((u8 *)blob));
arch/powerpc/platforms/powernv/pci-ioda.c:81:   printk("%spci %s: [PE# %.2x] %pV",
arch/powerpc/sysdev/tsi108_pci.c:63:    printk("PCI CFG write : ");
arch/powerpc/sysdev/tsi108_pci.c:64:    printk("%d:0x%x:0x%x ", bus->number, devfunc, offset);
arch/powerpc/sysdev/tsi108_pci.c:65:    printk("%d ADDR=0x%08x ", len, (uint) cfg_addr);
arch/powerpc/sysdev/tsi108_pci.c:164:           printk("PCI CFG read : ");
arch/powerpc/sysdev/tsi108_pci.c:165:           printk("%d:0x%x:0x%x ", bus->number, devfn, offset);
arch/powerpc/sysdev/tsi108_pci.c:166:           printk("%d ADDR=0x%08x ", len, (uint) cfg_addr);
arch/powerpc/sysdev/tsi108_pci.c:315:           printk("cfg_ctl=0x%08x ", temp);
arch/powerpc/xmon/nonstdio.c:181:               printk("%s", xmon_outbuf);



^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/xmon: Change printk() to pr_cont()
  2020-12-04 10:35 [PATCH] powerpc/xmon: Change printk() to pr_cont() Christophe Leroy
  2020-12-04 10:56 ` Michael Ellerman
@ 2020-12-10 11:29 ` Michael Ellerman
  1 sibling, 0 replies; 4+ messages in thread
From: Michael Ellerman @ 2020-12-10 11:29 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Christophe Leroy, Paul Mackerras,
	Michael Ellerman
  Cc: linux-kernel, linuxppc-dev

On Fri, 4 Dec 2020 10:35:38 +0000 (UTC), Christophe Leroy wrote:
> Since some time now, printk() adds carriage return, leading to
> unusable xmon output:
> 
> [   54.288722] sysrq: Entering xmon
> [   54.292209] Vector: 0  at [cace3d2c]
> [   54.292274]     pc:
> [   54.292331] c0023650
> [   54.292468] : xmon+0x28/0x58
> [   54.292519]
> [   54.292574]     lr:
> [   54.292630] c0023724
> [   54.292749] : sysrq_handle_xmon+0xa4/0xfc
> [   54.292801]
> [   54.292867]     sp: cace3de8
> [   54.292931]    msr: 9032
> [   54.292999]   current = 0xc28d0000
> [   54.293072]     pid   = 377, comm = sh
> [   54.293157] Linux version 5.10.0-rc6-s3k-dev-01364-gedf13f0ccd76-dirty (root@po17688vm.idsi0.si.c-s.fr) (powerpc64-linux-gcc (GCC) 10.1.0, GNU ld (GNU Binutils) 2.34) #4211 PREEMPT Fri Dec 4 09:32:11 UTC 2020
> [   54.293287] enter ? for help
> [   54.293470] [cace3de8]
> [   54.293532] c0023724
> [   54.293654]  sysrq_handle_xmon+0xa4/0xfc
> [   54.293711]  (unreliable)
> [   54.293859] [cace3e18]
> [   54.293918] c03885a8
> [   54.294056]  __handle_sysrq+0xe4/0x1d4
> [   54.294108]
> [   54.294255] [cace3e48]
> [   54.294314] c0388704
> [   54.294441]  write_sysrq_trigger+0x34/0x74
> [   54.294493]
> [   54.294641] [cace3e68]
> [   54.294700] c01f65d0
> [   54.294822]  proc_reg_write+0xac/0x11c
> [   54.294875]
> [   54.295023] [cace3e88]
> [   54.295082] c0179910
> [   54.295198]  vfs_write+0x134/0x46c
> [   54.295250]
> [   54.295396] [cace3f08]
> [   54.295455] c0179de8
> [   54.295567]  ksys_write+0x78/0x11c
> [   54.295619]
> [   54.295766] [cace3f38]
> [   54.295825] c00110d0
> [   54.295951]  ret_from_syscall+0x0/0x34
> [   54.296002]
> [   54.296159] --- Exception: c01 (System Call) at
> [   54.296217] 0fd4e784
> [   54.296303]
> [   54.296375] SP (7fca6ff0) is in userspace
> [   54.296431] mon>
> [   54.296484]  <no input ...>
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc/xmon: Change printk() to pr_cont()
      https://git.kernel.org/powerpc/c/7c6c86b36a36dd4a13d30bba07718e767aa2e7a1

cheers

^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-12-10 11:30 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2020-12-04 10:35 [PATCH] powerpc/xmon: Change printk() to pr_cont() Christophe Leroy
2020-12-04 10:56 ` Michael Ellerman
2020-12-04 15:55   ` Joe Perches
2020-12-10 11:29 ` Michael Ellerman

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