* [PATCH v3] init: Do not select DEBUG_KERNEL by default
@ 2019-04-11 0:56 Sinan Kaya
2019-04-11 2:39 ` Kees Cook
2019-04-11 5:31 ` Masahiro Yamada
0 siblings, 2 replies; 9+ messages in thread
From: Sinan Kaya @ 2019-04-11 0:56 UTC (permalink / raw)
To: linux-kernel
Cc: josh, Sinan Kaya, Kees Cook, Masahiro Yamada, Andrew Morton,
Peter Zijlstra (Intel),
Johannes Weiner, Nicholas Piggin, Mathieu Desnoyers,
Vasily Gorbik, Adrian Reber, Richard Guy Briggs, Andy Shevchenko,
Petr Mladek, Joe Lawrence, Matthew Wilcox, Randy Dunlap,
Mikulas Patocka, Robin Murphy, Tetsuo Handa, Changbin Du
We can't seem to have a kernel with CONFIG_EXPERT set but
CONFIG_DEBUG_KERNEL unset these days.
While some of the features under the CONFIG_EXPERT require
CONFIG_DEBUG_KERNEL, it doesn't apply for all features.
It looks like CONFIG_KALLSYMS_ALL is the only feature that
requires CONFIG_DEBUG_KERNEL.
Select CONFIG_EXPERT when CONFIG_DEBUG_KERNEL is chosen but
you can still choose CONFIG_EXPERT without CONFIG_DEBUG_KERNEL.
Signed-off-by: Sinan Kaya <okaya@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
init/Kconfig | 2 --
lib/Kconfig.debug | 1 +
2 files changed, 1 insertion(+), 2 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index 4592bf7997c0..37e10a8391a3 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1206,8 +1206,6 @@ config BPF
menuconfig EXPERT
bool "Configure standard kernel features (expert users)"
- # Unhide debug options, to make the on-by-default options visible
- select DEBUG_KERNEL
help
This option allows certain base kernel options and settings
to be disabled or tweaked. This is for specialized
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 0d9e81779e37..9fbf3499ec8d 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -434,6 +434,7 @@ config MAGIC_SYSRQ_SERIAL
config DEBUG_KERNEL
bool "Kernel debugging"
+ default EXPERT
help
Say Y here if you are developing drivers or trying to debug and
identify kernel problems.
--
2.21.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH v3] init: Do not select DEBUG_KERNEL by default
2019-04-11 0:56 [PATCH v3] init: Do not select DEBUG_KERNEL by default Sinan Kaya
@ 2019-04-11 2:39 ` Kees Cook
2019-04-11 5:33 ` Masahiro Yamada
2019-04-11 5:31 ` Masahiro Yamada
1 sibling, 1 reply; 9+ messages in thread
From: Kees Cook @ 2019-04-11 2:39 UTC (permalink / raw)
To: Sinan Kaya, Masahiro Yamada
Cc: LKML, Josh Triplett, Kees Cook, Andrew Morton,
Peter Zijlstra (Intel),
Johannes Weiner, Nicholas Piggin, Mathieu Desnoyers,
Vasily Gorbik, Adrian Reber, Richard Guy Briggs, Andy Shevchenko,
Petr Mladek, Joe Lawrence, Matthew Wilcox, Randy Dunlap,
Mikulas Patocka, Robin Murphy, Tetsuo Handa, Changbin Du
On Wed, Apr 10, 2019 at 5:56 PM Sinan Kaya <okaya@kernel.org> wrote:
>
> We can't seem to have a kernel with CONFIG_EXPERT set but
> CONFIG_DEBUG_KERNEL unset these days.
>
> While some of the features under the CONFIG_EXPERT require
> CONFIG_DEBUG_KERNEL, it doesn't apply for all features.
>
> It looks like CONFIG_KALLSYMS_ALL is the only feature that
> requires CONFIG_DEBUG_KERNEL.
>
> Select CONFIG_EXPERT when CONFIG_DEBUG_KERNEL is chosen but
> you can still choose CONFIG_EXPERT without CONFIG_DEBUG_KERNEL.
>
> Signed-off-by: Sinan Kaya <okaya@kernel.org>
> Reviewed-by: Kees Cook <keescook@chromium.org>
Masahiro, should this go via your tree, or somewhere else?
Thanks!
-Kees
> ---
> init/Kconfig | 2 --
> lib/Kconfig.debug | 1 +
> 2 files changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/init/Kconfig b/init/Kconfig
> index 4592bf7997c0..37e10a8391a3 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1206,8 +1206,6 @@ config BPF
>
> menuconfig EXPERT
> bool "Configure standard kernel features (expert users)"
> - # Unhide debug options, to make the on-by-default options visible
> - select DEBUG_KERNEL
> help
> This option allows certain base kernel options and settings
> to be disabled or tweaked. This is for specialized
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 0d9e81779e37..9fbf3499ec8d 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -434,6 +434,7 @@ config MAGIC_SYSRQ_SERIAL
>
> config DEBUG_KERNEL
> bool "Kernel debugging"
> + default EXPERT
> help
> Say Y here if you are developing drivers or trying to debug and
> identify kernel problems.
> --
> 2.21.0
>
--
Kees Cook
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3] init: Do not select DEBUG_KERNEL by default
2019-04-11 0:56 [PATCH v3] init: Do not select DEBUG_KERNEL by default Sinan Kaya
2019-04-11 2:39 ` Kees Cook
@ 2019-04-11 5:31 ` Masahiro Yamada
2019-04-11 5:42 ` Sinan Kaya
1 sibling, 1 reply; 9+ messages in thread
From: Masahiro Yamada @ 2019-04-11 5:31 UTC (permalink / raw)
To: Sinan Kaya
Cc: Linux Kernel Mailing List, Josh Triplett, Kees Cook,
Masahiro Yamada, Andrew Morton, Peter Zijlstra (Intel),
Johannes Weiner, Nicholas Piggin, Mathieu Desnoyers,
Vasily Gorbik, Adrian Reber, Richard Guy Briggs, Andy Shevchenko,
Petr Mladek, Joe Lawrence, Matthew Wilcox, Randy Dunlap,
Mikulas Patocka, Robin Murphy, Tetsuo Handa, Changbin Du
On Thu, Apr 11, 2019 at 9:59 AM Sinan Kaya <okaya@kernel.org> wrote:
>
> We can't seem to have a kernel with CONFIG_EXPERT set but
> CONFIG_DEBUG_KERNEL unset these days.
>
> While some of the features under the CONFIG_EXPERT require
> CONFIG_DEBUG_KERNEL, it doesn't apply for all features.
>
> It looks like CONFIG_KALLSYMS_ALL is the only feature that
> requires CONFIG_DEBUG_KERNEL.
Which part of KALLSYMS_ALL code requires CONFIG_DEBUG_KERNEL?
> Select CONFIG_EXPERT when CONFIG_DEBUG_KERNEL is chosen but
> you can still choose CONFIG_EXPERT without CONFIG_DEBUG_KERNEL.
>
> Signed-off-by: Sinan Kaya <okaya@kernel.org>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> ---
> init/Kconfig | 2 --
> lib/Kconfig.debug | 1 +
> 2 files changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/init/Kconfig b/init/Kconfig
> index 4592bf7997c0..37e10a8391a3 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1206,8 +1206,6 @@ config BPF
>
> menuconfig EXPERT
> bool "Configure standard kernel features (expert users)"
> - # Unhide debug options, to make the on-by-default options visible
> - select DEBUG_KERNEL
> help
> This option allows certain base kernel options and settings
> to be disabled or tweaked. This is for specialized
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 0d9e81779e37..9fbf3499ec8d 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -434,6 +434,7 @@ config MAGIC_SYSRQ_SERIAL
>
> config DEBUG_KERNEL
> bool "Kernel debugging"
> + default EXPERT
> help
> Say Y here if you are developing drivers or trying to debug and
> identify kernel problems.
> --
> 2.21.0
>
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3] init: Do not select DEBUG_KERNEL by default
2019-04-11 2:39 ` Kees Cook
@ 2019-04-11 5:33 ` Masahiro Yamada
2019-04-11 17:00 ` Kees Cook
0 siblings, 1 reply; 9+ messages in thread
From: Masahiro Yamada @ 2019-04-11 5:33 UTC (permalink / raw)
To: Kees Cook
Cc: Sinan Kaya, LKML, Josh Triplett, Andrew Morton,
Peter Zijlstra (Intel),
Johannes Weiner, Nicholas Piggin, Mathieu Desnoyers,
Vasily Gorbik, Adrian Reber, Richard Guy Briggs, Andy Shevchenko,
Petr Mladek, Joe Lawrence, Matthew Wilcox, Randy Dunlap,
Mikulas Patocka, Robin Murphy, Tetsuo Handa, Changbin Du
On Thu, Apr 11, 2019 at 11:47 AM Kees Cook <keescook@chromium.org> wrote:
>
> On Wed, Apr 10, 2019 at 5:56 PM Sinan Kaya <okaya@kernel.org> wrote:
> >
> > We can't seem to have a kernel with CONFIG_EXPERT set but
> > CONFIG_DEBUG_KERNEL unset these days.
> >
> > While some of the features under the CONFIG_EXPERT require
> > CONFIG_DEBUG_KERNEL, it doesn't apply for all features.
> >
> > It looks like CONFIG_KALLSYMS_ALL is the only feature that
> > requires CONFIG_DEBUG_KERNEL.
> >
> > Select CONFIG_EXPERT when CONFIG_DEBUG_KERNEL is chosen but
> > you can still choose CONFIG_EXPERT without CONFIG_DEBUG_KERNEL.
> >
> > Signed-off-by: Sinan Kaya <okaya@kernel.org>
> > Reviewed-by: Kees Cook <keescook@chromium.org>
>
> Masahiro, should this go via your tree, or somewhere else?
I think somewhere else.
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3] init: Do not select DEBUG_KERNEL by default
2019-04-11 5:31 ` Masahiro Yamada
@ 2019-04-11 5:42 ` Sinan Kaya
2019-04-11 5:48 ` Masahiro Yamada
0 siblings, 1 reply; 9+ messages in thread
From: Sinan Kaya @ 2019-04-11 5:42 UTC (permalink / raw)
To: Masahiro Yamada
Cc: Linux Kernel Mailing List, Josh Triplett, Kees Cook,
Andrew Morton, Peter Zijlstra (Intel),
Johannes Weiner, Nicholas Piggin, Mathieu Desnoyers,
Vasily Gorbik, Adrian Reber, Richard Guy Briggs, Andy Shevchenko,
Petr Mladek, Joe Lawrence, Matthew Wilcox, Randy Dunlap,
Mikulas Patocka, Robin Murphy, Tetsuo Handa, Changbin Du
On 4/11/2019 1:31 AM, Masahiro Yamada wrote:
>> t looks like CONFIG_KALLSYMS_ALL is the only feature that
>> requires CONFIG_DEBUG_KERNEL.
> Which part of KALLSYMS_ALL code requires CONFIG_DEBUG_KERNEL?
>
I was going by what Kconfig tells me
Symbol: KALLSYMS_ALL [=n]
Depends on: DEBUG_KERNEL [=n] && KALLSYMS [=y]
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3] init: Do not select DEBUG_KERNEL by default
2019-04-11 5:42 ` Sinan Kaya
@ 2019-04-11 5:48 ` Masahiro Yamada
2019-04-11 18:15 ` Sinan Kaya
0 siblings, 1 reply; 9+ messages in thread
From: Masahiro Yamada @ 2019-04-11 5:48 UTC (permalink / raw)
To: Sinan Kaya
Cc: Linux Kernel Mailing List, Josh Triplett, Kees Cook,
Andrew Morton, Peter Zijlstra (Intel),
Johannes Weiner, Nicholas Piggin, Mathieu Desnoyers,
Vasily Gorbik, Adrian Reber, Richard Guy Briggs, Andy Shevchenko,
Petr Mladek, Joe Lawrence, Matthew Wilcox, Randy Dunlap,
Mikulas Patocka, Robin Murphy, Tetsuo Handa, Changbin Du
On Thu, Apr 11, 2019 at 2:44 PM Sinan Kaya <Okaya@kernel.org> wrote:
>
> On 4/11/2019 1:31 AM, Masahiro Yamada wrote:
> >> t looks like CONFIG_KALLSYMS_ALL is the only feature that
> >> requires CONFIG_DEBUG_KERNEL.
> > Which part of KALLSYMS_ALL code requires CONFIG_DEBUG_KERNEL?
> >
>
> I was going by what Kconfig tells me
>
> Symbol: KALLSYMS_ALL [=n]
> Depends on: DEBUG_KERNEL [=n] && KALLSYMS [=y]
Lots of features have 'depends on DEBUG_KERNEL'.
What is special about KALLSYMS_ALL here?
./drivers/gpio/Kconfig:52: depends on DEBUG_KERNEL
./drivers/pci/Kconfig:69: depends on DEBUG_KERNEL
./drivers/usb/gadget/Kconfig:51: depends on DEBUG_KERNEL
./drivers/base/Kconfig:119: depends on DEBUG_KERNEL
./drivers/base/Kconfig:130: depends on DEBUG_KERNEL
./drivers/base/Kconfig:142: depends on DEBUG_KERNEL
./drivers/spi/Kconfig:29: depends on DEBUG_KERNEL
./drivers/pinctrl/Kconfig:29: depends on DEBUG_KERNEL
./drivers/gpu/drm/Kconfig:55: depends on DEBUG_KERNEL
./kernel/rcu/Kconfig.debug:16: depends on DEBUG_KERNEL
./kernel/rcu/Kconfig.debug:33: depends on DEBUG_KERNEL
./kernel/rcu/Kconfig.debug:61: depends on DEBUG_KERNEL
./kernel/rcu/Kconfig.debug:73: depends on DEBUG_KERNEL
./net/dccp/Kconfig:30: depends on DEBUG_KERNEL=y
./crypto/Kconfig:173: depends on DEBUG_KERNEL && !CRYPTO_MANAGER_DISABLE_TESTS
./init/Kconfig:951: depends on DEBUG_KERNEL
./init/Kconfig:1476: depends on DEBUG_KERNEL && KALLSYMS
./mm/Kconfig.debug:12: depends on DEBUG_KERNEL
./mm/Kconfig.debug:44: depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
./mm/Kconfig.debug:99: depends on DEBUG_KERNEL
./mm/Kconfig:494: depends on DEBUG_KERNEL && CMA
./lib/Kconfig.kgdb:8: depends on DEBUG_KERNEL
./lib/Kconfig.debug:80: depends on DEBUG_KERNEL && PRINTK &&
GENERIC_CALIBRATE_DELAY
./lib/Kconfig.debug:172: depends on DEBUG_KERNEL && !COMPILE_TEST
./lib/Kconfig.debug:264: depends on DEBUG_KERNEL
./lib/Kconfig.debug:363: depends on DEBUG_KERNEL && (M68K || UML ||
SUPERH) || ARCH_WANT_FRAME_POINTERS
./lib/Kconfig.debug:387: depends on DEBUG_KERNEL
./lib/Kconfig.debug:447: depends on DEBUG_KERNEL
./lib/Kconfig.debug:508: depends on DEBUG_KERNEL && SLAB
./lib/Kconfig.debug:549: depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
./lib/Kconfig.debug:614: depends on DEBUG_KERNEL && !IA64
./lib/Kconfig.debug:623: depends on DEBUG_KERNEL
./lib/Kconfig.debug:661: depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
./lib/Kconfig.debug:670: depends on DEBUG_KERNEL && !MMU
./lib/Kconfig.debug:712: depends on DEBUG_KERNEL
./lib/Kconfig.debug:723: depends on DEBUG_KERNEL && HIGHMEM
./lib/Kconfig.debug:733: depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
./lib/Kconfig.debug:802: depends on DEBUG_KERNEL
./lib/Kconfig.debug:816: depends on DEBUG_KERNEL && !S390
./lib/Kconfig.debug:868: depends on DEBUG_KERNEL && !S390
./lib/Kconfig.debug:902: depends on DEBUG_KERNEL
./lib/Kconfig.debug:956: depends on DEBUG_KERNEL
./lib/Kconfig.debug:997: depends on DEBUG_KERNEL && PROC_FS
./lib/Kconfig.debug:1010: depends on DEBUG_KERNEL && PROC_FS
./lib/Kconfig.debug:1023: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1048: depends on DEBUG_KERNEL && PREEMPT &&
TRACE_IRQFLAGS_SUPPORT
./lib/Kconfig.debug:1065: depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
./lib/Kconfig.debug:1111: depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
./lib/Kconfig.debug:1133: depends on DEBUG_KERNEL && RT_MUTEXES
./lib/Kconfig.debug:1140: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1150: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1157: depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
./lib/Kconfig.debug:1174: depends on DEBUG_KERNEL && RWSEM_SPIN_ON_OWNER
./lib/Kconfig.debug:1181: depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
./lib/Kconfig.debug:1196: depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
./lib/Kconfig.debug:1207: depends on DEBUG_KERNEL && LOCKDEP
./lib/Kconfig.debug:1216: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1226: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1237: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1308: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1346: depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
./lib/Kconfig.debug:1355: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1365: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1375: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1385: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1402: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1417: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1444: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1457: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1536: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1615: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1680: depends on DEBUG_KERNEL || m
./lib/Kconfig.debug:1690: depends on DEBUG_KERNEL || m
./lib/Kconfig.debug:1699: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1710: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1724: depends on DEBUG_KERNEL
./lib/Kconfig.debug:1731: depends on DEBUG_KERNEL
./arch/xtensa/Kconfig.debug:5: depends on DEBUG_KERNEL && MMU
./arch/x86/Kconfig.debug:70: depends on DEBUG_KERNEL
./arch/x86/Kconfig.debug:129: depends on DEBUG_KERNEL
./arch/x86/Kconfig.debug:174: depends on DEBUG_KERNEL && KPROBES
./arch/x86/Kconfig.debug:258: depends on DEBUG_KERNEL
./arch/x86/Kconfig.debug:265: depends on DEBUG_KERNEL
./arch/x86/Kconfig.debug:285: depends on DEBUG_KERNEL
./arch/x86/Kconfig.debug:295: depends on DEBUG_KERNEL && X86_LOCAL_APIC
./arch/x86/Kconfig.debug:319: depends on DEBUG_KERNEL
./arch/ia64/Kconfig.debug:23: depends on DEBUG_KERNEL
./arch/ia64/Kconfig.debug:33: depends on DEBUG_KERNEL
./arch/ia64/Kconfig.debug:42: depends on DEBUG_KERNEL
./arch/ia64/Kconfig.debug:51: depends on DEBUG_KERNEL
./arch/s390/Kconfig.debug:8: depends on DEBUG_KERNEL
./arch/powerpc/Kconfig.debug:57: depends on DEBUG_KERNEL
./arch/powerpc/Kconfig.debug:70: depends on DEBUG_KERNEL &&
JUMP_LABEL_FEATURE_CHECKS
./arch/powerpc/Kconfig.debug:79: depends on DEBUG_KERNEL
./arch/powerpc/Kconfig.debug:83: depends on DEBUG_KERNEL
./arch/powerpc/Kconfig.debug:90: depends on DEBUG_KERNEL
./arch/powerpc/Kconfig.debug:127: depends on DEBUG_KERNEL && PPC32
./arch/powerpc/Kconfig.debug:355: depends on DEBUG_KERNEL && DEBUG_FS
./arch/powerpc/Kconfig.debug:366: depends on DEBUG_KERNEL &&
PPC_BOOK3S_64
./arch/arm/Kconfig.debug:8: depends on DEBUG_KERNEL
./arch/arm/Kconfig.debug:105: depends on DEBUG_KERNEL
./arch/arm64/Kconfig.debug:7: depends on DEBUG_KERNEL
./arch/unicore32/Kconfig.debug:17: depends on DEBUG_KERNEL
./arch/mips/Kconfig.debug:90: depends on DEBUG_KERNEL && SYS_SUPPORTS_ZBOOT
./arch/sh/Kconfig.debug:22: depends on DEBUG_KERNEL && SUPERH32
./arch/sh/Kconfig.debug:31: depends on DEBUG_KERNEL && (MMU || BROKEN)
&& !PAGE_SIZE_64KB
./arch/sh/Kconfig.debug:41: depends on DEBUG_KERNEL && SUPERH32 && BROKEN
./arch/sh/Kconfig.debug:49: depends on DEBUG_KERNEL && SUPERH32
./arch/sh/Kconfig.debug:70: depends on DEBUG_KERNEL
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3] init: Do not select DEBUG_KERNEL by default
2019-04-11 5:33 ` Masahiro Yamada
@ 2019-04-11 17:00 ` Kees Cook
2019-04-11 22:18 ` Josh Triplett
0 siblings, 1 reply; 9+ messages in thread
From: Kees Cook @ 2019-04-11 17:00 UTC (permalink / raw)
To: Masahiro Yamada, Andrew Morton
Cc: Sinan Kaya, LKML, Josh Triplett, Peter Zijlstra (Intel),
Johannes Weiner, Nicholas Piggin, Mathieu Desnoyers,
Vasily Gorbik, Adrian Reber, Richard Guy Briggs, Andy Shevchenko,
Petr Mladek, Joe Lawrence, Matthew Wilcox, Randy Dunlap,
Mikulas Patocka, Robin Murphy, Tetsuo Handa
On Wed, Apr 10, 2019 at 10:34 PM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> On Thu, Apr 11, 2019 at 11:47 AM Kees Cook <keescook@chromium.org> wrote:
> >
> > On Wed, Apr 10, 2019 at 5:56 PM Sinan Kaya <okaya@kernel.org> wrote:
> > >
> > > We can't seem to have a kernel with CONFIG_EXPERT set but
> > > CONFIG_DEBUG_KERNEL unset these days.
> > >
> > > While some of the features under the CONFIG_EXPERT require
> > > CONFIG_DEBUG_KERNEL, it doesn't apply for all features.
> > >
> > > It looks like CONFIG_KALLSYMS_ALL is the only feature that
> > > requires CONFIG_DEBUG_KERNEL.
> > >
> > > Select CONFIG_EXPERT when CONFIG_DEBUG_KERNEL is chosen but
> > > you can still choose CONFIG_EXPERT without CONFIG_DEBUG_KERNEL.
> > >
> > > Signed-off-by: Sinan Kaya <okaya@kernel.org>
> > > Reviewed-by: Kees Cook <keescook@chromium.org>
> >
> > Masahiro, should this go via your tree, or somewhere else?
>
>
> I think somewhere else.
Okay. Andrew, can you take this?
--
Kees Cook
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3] init: Do not select DEBUG_KERNEL by default
2019-04-11 5:48 ` Masahiro Yamada
@ 2019-04-11 18:15 ` Sinan Kaya
0 siblings, 0 replies; 9+ messages in thread
From: Sinan Kaya @ 2019-04-11 18:15 UTC (permalink / raw)
To: Masahiro Yamada
Cc: Linux Kernel Mailing List, Josh Triplett, Kees Cook,
Andrew Morton, Peter Zijlstra (Intel),
Johannes Weiner, Nicholas Piggin, Mathieu Desnoyers,
Vasily Gorbik, Adrian Reber, Richard Guy Briggs, Andy Shevchenko,
Petr Mladek, Joe Lawrence, Matthew Wilcox, Randy Dunlap,
Mikulas Patocka, Robin Murphy, Tetsuo Handa, Changbin Du
On 4/11/2019 1:48 AM, Masahiro Yamada wrote:
>> I was going by what Kconfig tells me
>>
>> Symbol: KALLSYMS_ALL [=n]
>> Depends on: DEBUG_KERNEL [=n] && KALLSYMS [=y]
> Lots of features have 'depends on DEBUG_KERNEL'.
> What is special about KALLSYMS_ALL here?
I had to do some learning about KALLSYSM_ALL. Based on my limited
searching, KALLSYMS_ALL allows you to locate the symbol location
at runtime from the kernel.
Without KALLSYM_ALL, you can only locate the kernel code only. With
KALLSYMS_ALL, you can locate the symbols for any data structure
including kernel modules.
I'm not a KALLSYMS person but based on my search, I'd consider
KALLSYMS_ALL a debug feature as it is today.
kernel/kallsyms.c: else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
kernel/livepatch/Kconfig: depends on KALLSYMS_ALL
kernel/module.c:#ifdef CONFIG_KALLSYMS_ALL
kernel/module.c:#ifndef CONFIG_KALLSYMS_ALL
lib/Kconfig.debug: select KALLSYMS_ALL
config LOCKDEP
bool
depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
select KALLSYMS
select KALLSYMS_ALL
lib/Kconfig.debug: select KALLSYMS_ALL
config LATENCYTOP
bool "Latency measuring infrastructure"
select KALLSYMS
select KALLSYMS_ALL
scripts/link-vmlinux.sh: if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3] init: Do not select DEBUG_KERNEL by default
2019-04-11 17:00 ` Kees Cook
@ 2019-04-11 22:18 ` Josh Triplett
0 siblings, 0 replies; 9+ messages in thread
From: Josh Triplett @ 2019-04-11 22:18 UTC (permalink / raw)
To: Kees Cook
Cc: Masahiro Yamada, Andrew Morton, Sinan Kaya, LKML,
Peter Zijlstra (Intel),
Johannes Weiner, Nicholas Piggin, Mathieu Desnoyers,
Vasily Gorbik, Adrian Reber, Richard Guy Briggs, Andy Shevchenko,
Petr Mladek, Joe Lawrence, Matthew Wilcox, Randy Dunlap,
Mikulas Patocka, Robin Murphy, Tetsuo Handa
On Thu, Apr 11, 2019 at 10:00:24AM -0700, Kees Cook wrote:
> On Wed, Apr 10, 2019 at 10:34 PM Masahiro Yamada
> <yamada.masahiro@socionext.com> wrote:
> >
> > On Thu, Apr 11, 2019 at 11:47 AM Kees Cook <keescook@chromium.org> wrote:
> > >
> > > On Wed, Apr 10, 2019 at 5:56 PM Sinan Kaya <okaya@kernel.org> wrote:
> > > >
> > > > We can't seem to have a kernel with CONFIG_EXPERT set but
> > > > CONFIG_DEBUG_KERNEL unset these days.
> > > >
> > > > While some of the features under the CONFIG_EXPERT require
> > > > CONFIG_DEBUG_KERNEL, it doesn't apply for all features.
> > > >
> > > > It looks like CONFIG_KALLSYMS_ALL is the only feature that
> > > > requires CONFIG_DEBUG_KERNEL.
> > > >
> > > > Select CONFIG_EXPERT when CONFIG_DEBUG_KERNEL is chosen but
> > > > you can still choose CONFIG_EXPERT without CONFIG_DEBUG_KERNEL.
> > > >
> > > > Signed-off-by: Sinan Kaya <okaya@kernel.org>
> > > > Reviewed-by: Kees Cook <keescook@chromium.org>
> > >
> > > Masahiro, should this go via your tree, or somewhere else?
> >
> >
> > I think somewhere else.
>
> Okay. Andrew, can you take this?
Echoing my comment from the previous thread: this does not seem like the
right solution to me and it introduces a new problem. Please see my
response to v2 for a quick alternative that would address the underlying
bug, which is that some code generation depends on DEBUG_KERNEL.
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2019-04-11 22:18 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-04-11 0:56 [PATCH v3] init: Do not select DEBUG_KERNEL by default Sinan Kaya
2019-04-11 2:39 ` Kees Cook
2019-04-11 5:33 ` Masahiro Yamada
2019-04-11 17:00 ` Kees Cook
2019-04-11 22:18 ` Josh Triplett
2019-04-11 5:31 ` Masahiro Yamada
2019-04-11 5:42 ` Sinan Kaya
2019-04-11 5:48 ` Masahiro Yamada
2019-04-11 18:15 ` Sinan Kaya
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