diff options
| author | Christophe Leroy <christophe.leroy@c-s.fr> | 2018-10-20 09:26:49 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-10-22 04:07:24 +0200 |
| commit | 977e4be5eb714c48a67afc26a6c477f24130a1f2 (patch) | |
| tree | 6efdd00663fdbc06815a8412d76fbd8568257562 /kernel/sched | |
| parent | x86/mm: Kill stray kernel fault handling comment (diff) | |
| download | linux-977e4be5eb714c48a67afc26a6c477f24130a1f2.tar.xz linux-977e4be5eb714c48a67afc26a6c477f24130a1f2.zip | |
x86/stackprotector: Remove the call to boot_init_stack_canary() from cpu_startup_entry()
The following commit:
d7880812b359 ("idle: Add the stack canary init to cpu_startup_entry()")
... added an x86 specific boot_init_stack_canary() call to the generic
cpu_startup_entry() as a temporary hack, with the intention to remove
the #ifdef CONFIG_X86 later.
More than 5 years later let's finally realize that plan! :-)
While implementing stack protector support for PowerPC, we found
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 architectures
using a global stack canary (ARM, SH, MIPS and XTENSA).
Instead of modifying the #ifdef CONFIG_X86 to an even messier:
#if defined(CONFIG_X86) || defined(CONFIG_PPC)
PowerPC implemented the call to boot_init_stack_canary() in the function
calling cpu_startup_entry().
Let's try the same cleanup on the x86 side as well.
On x86 we have two functions calling cpu_startup_entry():
- start_secondary()
- cpu_bringup_and_idle()
start_secondary() already calls boot_init_stack_canary(), so
it's good, and this patch adds the call to boot_init_stack_canary()
in cpu_bringup_and_idle().
I.e. now x86 catches up to the rest of the world and the ugly init
sequence in init/main.c can be removed from cpu_startup_entry().
As a final benefit we can also remove the <linux/stackprotector.h>
dependency from <linux/sched.h>.
[ mingo: Improved the changelog a bit, added language explaining x86 borkage and sched.h change. ]
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/20181020072649.5B59310483E@pc16082vm.idsi0.si.c-s.fr
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/idle.c | 15 | ||||
| -rw-r--r-- | kernel/sched/sched.h | 1 |
2 files changed, 0 insertions, 16 deletions
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) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 4a2e8cae63c4..5b00a816a4b3 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -56,7 +56,6 @@ #include <linux/profile.h> #include <linux/rcupdate_wait.h> #include <linux/security.h> -#include <linux/stackprotector.h> #include <linux/stop_machine.h> #include <linux/suspend.h> #include <linux/swait.h> |