Commit 43567139 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86_urgent_for_v5.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 fix from Borislav Petkov:
 "A single fix for early boot crashes of kernels built with gcc10 and
  stack protector enabled"

* tag 'x86_urgent_for_v5.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86: Fix early boot crash on gcc-10, third try
parents 5a9ffb95 a9a3ed1e

arch/x86/include/asm/stackprotector.h

+6 −1
Original line number Diff line number Diff line
@@ -55,8 +55,13 @@ 
/*

 * Initialize the stackprotector canary value.

 *

 * NOTE: this must only be called from functions that never return,

 * NOTE: this must only be called from functions that never return

 * and it must always be inlined.

 *

 * In addition, it should be called from a compilation unit for which

 * stack protector is disabled. Alternatively, the caller should not end

 * with a function call which gets tail-call optimized as that would

 * lead to checking a modified canary value.

 */

static __always_inline void boot_init_stack_canary(void)

{

arch/x86/kernel/smpboot.c

+8 −0
Original line number Diff line number Diff line
@@ -266,6 +266,14 @@ static void notrace start_secondary(void *unused) 


	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();

}



/**

arch/x86/xen/smp_pv.c

+1 −0
Original line number Diff line number Diff line
@@ -93,6 +93,7 @@ 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)

include/linux/compiler.h

+6 −0
Original line number Diff line number Diff line
@@ -356,4 +356,10 @@ static inline void *offset_to_ptr(const int *off) 
/* &a[0] degrades to a pointer: a different type from an array */

#define __must_be_array(a)	BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))



/*

 * This is needed in functions which generate the stack canary, see

 * arch/x86/kernel/smpboot.c::start_secondary() for an example.

 */

#define prevent_tail_call_optimization()	mb()



#endif /* __LINUX_COMPILER_H */

init/main.c

+2 −0
Original line number Diff line number Diff line
@@ -1038,6 +1038,8 @@ asmlinkage __visible void __init start_kernel(void) 


	/* Do the rest non-__init'ed, we're now alive */

	arch_call_rest_init();



	prevent_tail_call_optimization();

}



/* Call all constructor functions linked into the kernel. */

CRA Git | Maintained and supported by SUSTech CRA and CCSE