The following commit has been merged into the x86/cpu branch of tip:
Commit-ID: c9a1ff316bc9b1d1806a4366d0aef6e18833ba52
Gitweb: https://git.kernel.org/tip/c9a1ff316bc9b1d1806a4366d0aef6e18833ba52
Author: Brian Gerst <brgerst@xxxxxxxxx>
AuthorDate: Wed, 17 Jun 2020 18:56:24 -04:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Thu, 18 Jun 2020 13:09:17 +02:00
x86/stackprotector: Pre-initialize canary for secondary CPUs
The idle tasks created for each secondary CPU already have a random stack
canary generated by fork(). Copy the canary to the percpu variable before
starting the secondary CPU which removes the need to call
boot_init_stack_canary().
Signed-off-by: Brian Gerst <brgerst@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/20200617225624.799335-1-brgerst@xxxxxxxxx
---
arch/x86/include/asm/stackprotector.h | 12 ++++++++++++
arch/x86/kernel/smpboot.c | 14 ++------------
arch/x86/xen/smp_pv.c | 2 --
3 files changed, 14 insertions(+), 14 deletions(-)
diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h
index 9804a79..7fb482f 100644
--- a/arch/x86/include/asm/stackprotector.h
+++ b/arch/x86/include/asm/stackprotector.h
@@ -90,6 +90,15 @@ static __always_inline void boot_init_stack_canary(void)
#endif
}
+static inline void cpu_init_stack_canary(int cpu, struct task_struct *idle)
+{
+#ifdef CONFIG_X86_64
+ per_cpu(fixed_percpu_data.stack_canary, cpu) = idle->stack_canary;
+#else
+ per_cpu(stack_canary.canary, cpu) = idle->stack_canary;
+#endif
+}
+
static inline void setup_stack_canary_segment(int cpu)
{
#ifdef CONFIG_X86_32
@@ -119,6 +128,9 @@ static inline void load_stack_canary_segment(void)
static inline void setup_stack_canary_segment(int cpu)
{ }
+static inline void cpu_init_stack_canary(int cpu, struct task_struct *idle)
+{ }
+
static inline void load_stack_canary_segment(void)
{
#ifdef CONFIG_X86_32
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index ffbd9a3..a11bd53 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -51,7 +51,6 @@
#include <linux/err.h>
#include <linux/nmi.h>
#include <linux/tboot.h>
-#include <linux/stackprotector.h>
#include <linux/gfp.h>
#include <linux/cpuidle.h>
#include <linux/numa.h>
@@ -80,6 +79,7 @@
#include <asm/cpu_device_id.h>
#include <asm/spec-ctrl.h>
#include <asm/hw_irq.h>
+#include <asm/stackprotector.h>
/* representing HT siblings of each logical CPU */
DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_sibling_map);
@@ -259,21 +259,10 @@ static void notrace start_secondary(void *unused)
/* enable local interrupts */
local_irq_enable();
- /* to prevent fake stack check failure in clock setup */
- boot_init_stack_canary();
-
x86_cpuinit.setup_percpu_clockev();
wmb();
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
-
- /*
- * Prevent tail call to cpu_startup_entry() because the stack protector
- * guard has been changed a couple of function calls up, in
- * boot_init_stack_canary() and must not be checked before tail calling
- * another function.
- */
- prevent_tail_call_optimization();
}
/**
@@ -1011,6 +1000,7 @@ int common_cpu_up(unsigned int cpu, struct task_struct *idle)
alternatives_enable_smp();
per_cpu(current_task, cpu) = idle;
+ cpu_init_stack_canary(cpu, idle);
/* Initialize the interrupt stack(s) */
ret = irq_init_percpu_irqstack(cpu);
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index 171aff1..9ea598d 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -92,9 +92,7 @@ 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);
- prevent_tail_call_optimization();
}
void xen_smp_intr_free_pv(unsigned int cpu)
|