commit d7880812b359 ("idle: Add the stack canary init to
cpu_startup_entry()") added the call to boot_init_stack_canary()
in cpu_startup_entry() in an #ifdef CONFIG_X86 statement, with
the intention to remove that #ifdef later.
While implementing stack protector for powerpc, it has been
observed that calling boot_init_stack_canary() is also needed
for powerpc which uses per task (TLS) stack canary like the X86.
However, calling boot_init_stack_canary() would break arches
using global stack canary (ARM, SH, MIPS and XTENSA).
Instead of adding modifying the #ifdef in a
implemented the call to boot_init_stack_canary() in the function
calling cpu_startup_entry()
On x86, we have two functions calling cpu_startup_entry():
- start_secondary()
- cpu_bringup_and_idle()
start_secondary() already calls boot_init_stack_canary().
This patch adds the call to boot_init_stack_canary() in
cpu_bringup_and_idle() and removes it from cpu_startup_entry()
Signed-off-by: Christophe Leroy <[email protected]>
---
arch/x86/xen/smp_pv.c | 1 +
kernel/sched/idle.c | 15 ---------------
2 files changed, 1 insertion(+), 15 deletions(-)
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index e3b18ad49889..0e05e8e23998 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -88,6 +88,7 @@ static void cpu_bringup(void)
asmlinkage __visible void cpu_bringup_and_idle(void)
{
cpu_bringup();
+ boot_init_stack_canary();
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 16f84142f2f4..f5516bae0c1b 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -347,21 +347,6 @@ EXPORT_SYMBOL_GPL(play_idle);
void cpu_startup_entry(enum cpuhp_state state)
{
- /*
- * This #ifdef needs to die, but it's too late in the cycle to
- * make this generic (ARM and SH have never invoked the canary
- * init for the non boot CPUs!). Will be fixed in 3.11
- */
-#ifdef CONFIG_X86
- /*
- * If we're the non-boot CPU, nothing set the stack canary up
- * for us. The boot CPU already has it initialized but no harm
- * in doing it again. This is a good place for updating it, as
- * we wont ever return from this function (so the invalid
- * canaries already on the stack wont ever trigger).
- */
- boot_init_stack_canary();
-#endif
arch_cpu_idle_prepare();
cpuhp_online_idle(state);
while (1)
--
2.13.3
On 19/10/2018 11:29, Christophe Leroy wrote:
> commit d7880812b359 ("idle: Add the stack canary init to
> cpu_startup_entry()") added the call to boot_init_stack_canary()
> in cpu_startup_entry() in an #ifdef CONFIG_X86 statement, with
> the intention to remove that #ifdef later.
>
> While implementing stack protector for powerpc, it has been
> observed that calling boot_init_stack_canary() is also needed
> for powerpc which uses per task (TLS) stack canary like the X86.
>
> However, calling boot_init_stack_canary() would break arches
> using global stack canary (ARM, SH, MIPS and XTENSA).
>
> Instead of adding modifying the #ifdef in a
> implemented the call to boot_init_stack_canary() in the function
> calling cpu_startup_entry()
I can't parse this sentence.
>
> On x86, we have two functions calling cpu_startup_entry():
> - start_secondary()
> - cpu_bringup_and_idle()
>
> start_secondary() already calls boot_init_stack_canary().
>
> This patch adds the call to boot_init_stack_canary() in
> cpu_bringup_and_idle() and removes it from cpu_startup_entry()
>
> Signed-off-by: Christophe Leroy <[email protected]>
With the commit message made understandable you can add my
Reviewed-by: Juergen Gross <[email protected]>
Juergen
Le 19/10/2018 à 12:01, Juergen Gross a écrit :
> On 19/10/2018 11:29, Christophe Leroy wrote:
>> commit d7880812b359 ("idle: Add the stack canary init to
>> cpu_startup_entry()") added the call to boot_init_stack_canary()
>> in cpu_startup_entry() in an #ifdef CONFIG_X86 statement, with
>> the intention to remove that #ifdef later.
>>
>> While implementing stack protector for powerpc, it has been
>> observed that calling boot_init_stack_canary() is also needed
>> for powerpc which uses per task (TLS) stack canary like the X86.
>>
>> However, calling boot_init_stack_canary() would break arches
>> using global stack canary (ARM, SH, MIPS and XTENSA).
>>
>> Instead of adding modifying the #ifdef in a
>> implemented the call to boot_init_stack_canary() in the function
>> calling cpu_startup_entry()
>
> I can't parse this sentence.
Oops, git commit took the #if for a comment and droped it. Fixed in v2.
>
>>
>> On x86, we have two functions calling cpu_startup_entry():
>> - start_secondary()
>> - cpu_bringup_and_idle()
>>
>> start_secondary() already calls boot_init_stack_canary().
>>
>> This patch adds the call to boot_init_stack_canary() in
>> cpu_bringup_and_idle() and removes it from cpu_startup_entry()
>>
>> Signed-off-by: Christophe Leroy <[email protected]>
>
> With the commit message made understandable you can add my
>
> Reviewed-by: Juergen Gross <[email protected]>
>
Thanks
Christophe
Hi Christophe,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on xen-tip/linux-next]
[also build test ERROR on v4.19-rc8 next-20181019]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Christophe-Leroy/idle-x86-remove-the-call-to-boot_init_stack_canary-from-cpu_startup_entry/20181020-015124
base: https://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git linux-next
config: x86_64-randconfig-s1-10200246 (attached as .config)
compiler: gcc-6 (Debian 6.4.0-9) 6.4.0 20171026
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64
All errors (new ones prefixed by >>):
arch/x86//xen/smp_pv.c: In function 'cpu_bringup_and_idle':
>> arch/x86//xen/smp_pv.c:91:2: error: implicit declaration of function 'boot_init_stack_canary' [-Werror=implicit-function-declaration]
boot_init_stack_canary();
^~~~~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
vim +/boot_init_stack_canary +91 arch/x86//xen/smp_pv.c
87
88 asmlinkage __visible void cpu_bringup_and_idle(void)
89 {
90 cpu_bringup();
> 91 boot_init_stack_canary();
92 cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
93 }
94
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
Hi Christophe,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on xen-tip/linux-next]
[also build test ERROR on v4.19-rc8 next-20181019]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Christophe-Leroy/idle-x86-remove-the-call-to-boot_init_stack_canary-from-cpu_startup_entry/20181020-015124
base: https://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git linux-next
config: x86_64-allmodconfig (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64
All errors (new ones prefixed by >>):
arch/x86/xen/smp_pv.c: In function 'cpu_bringup_and_idle':
>> arch/x86/xen/smp_pv.c:91:2: error: implicit declaration of function 'boot_init_stack_canary'; did you mean 'snprint_stack_trace'? [-Werror=implicit-function-declaration]
boot_init_stack_canary();
^~~~~~~~~~~~~~~~~~~~~~
snprint_stack_trace
cc1: some warnings being treated as errors
vim +91 arch/x86/xen/smp_pv.c
87
88 asmlinkage __visible void cpu_bringup_and_idle(void)
89 {
90 cpu_bringup();
> 91 boot_init_stack_canary();
92 cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
93 }
94
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation