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Commit d7880812 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

idle: Add the stack canary init to cpu_startup_entry() 



Moving x86 to the generic idle implementation (commit 7d1a9417 "x86:
Use generic idle loop") wreckaged the stack protector.

I stupidly missed that boot_init_stack_canary() must be inlined from a
function which never returns, but I put that call into
arch_cpu_idle_prepare() which of course returns.

I pondered to play tricks with arch_cpu_idle_prepare() first, but then
I noticed, that the other archs which have implemented the
stackprotector (ARM and SH) do not initialize the canary for the
non-boot cpus.

So I decided to move the boot_init_stack_canary() call into
cpu_startup_entry() ifdeffed with an CONFIG_X86 for now. This #ifdef
is just a temporary measure as I don't want to inflict the
boot_init_stack_canary() call on ARM and SH that late in the cycle.

I'll queue a patch for 3.11 which removes the #ifdef if the ARM/SH
maintainers have no objection.

Reported-by: default avatarWouter van Kesteren <woutershep@gmail.com>
Cc: x86@kernel.org
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent c7788792

arch/x86/kernel/process.c

+0 −12
Original line number Original line Diff line number Diff line
@@ -277,18 +277,6 @@ void exit_idle(void) 
}

}

#endif

#endif





void arch_cpu_idle_prepare(void)

{

	/*

	 * If we're the non-boot CPU, nothing set the stack canary up

	 * for us.  CPU0 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();

}



void arch_cpu_idle_enter(void)

void arch_cpu_idle_enter(void)

{

{

	local_touch_nmi();

	local_touch_nmi();

kernel/cpu/idle.c

+16 −0
Original line number Original line Diff line number Diff line
@@ -5,6 +5,7 @@ 
#include <linux/cpu.h>

#include <linux/cpu.h>

#include <linux/tick.h>

#include <linux/tick.h>

#include <linux/mm.h>

#include <linux/mm.h>

#include <linux/stackprotector.h>





#include <asm/tlb.h>

#include <asm/tlb.h>
@@ -112,6 +113,21 @@ static void cpu_idle_loop(void) 




void cpu_startup_entry(enum cpuhp_state state)

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

	current_set_polling();

	current_set_polling();

	arch_cpu_idle_prepare();

	arch_cpu_idle_prepare();

	cpu_idle_loop();

	cpu_idle_loop();