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Commit 4205a89b authored by Marc Zyngier's avatar Marc Zyngier
Browse files

arm64: Make BP hardening slot counter available 



We're about to need to allocate hardening slots from other parts
of the kernel (in order to support ARM64_HARDEN_EL2_VECTORS).

Turn the counter into an atomic_t and make it available to the
rest of the kernel. Also add BP_HARDEN_EL2_SLOTS as the number of
slots instead of the hardcoded 4...

Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: default avatarAndrew Jones <drjones@redhat.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent dc2e4633

arch/arm64/include/asm/mmu.h

+3 −0
Original line number Diff line number Diff line
@@ -21,6 +21,8 @@ 
#define USER_ASID_FLAG	(UL(1) << USER_ASID_BIT)

#define TTBR_ASID_MASK	(UL(0xffff) << 48)



#define BP_HARDEN_EL2_SLOTS 4



#ifndef __ASSEMBLY__



typedef struct {
@@ -51,6 +53,7 @@ struct bp_hardening_data { 


#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR

extern char __bp_harden_hyp_vecs_start[], __bp_harden_hyp_vecs_end[];

extern atomic_t arm64_el2_vector_last_slot;



DECLARE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data);

arch/arm64/kernel/bpi.S

+2 −1
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/arm-smccc.h>



#include <asm/alternative.h>

#include <asm/mmu.h>



.macro hyp_ventry

	.align 7
@@ -66,7 +67,7 @@ alternative_cb_end 


	.align	11

ENTRY(__bp_harden_hyp_vecs_start)

	.rept 4

	.rept BP_HARDEN_EL2_SLOTS

	generate_vectors

	.endr

ENTRY(__bp_harden_hyp_vecs_end)

arch/arm64/kernel/cpu_errata.c

+4 −5
Original line number Diff line number Diff line
@@ -60,6 +60,8 @@ static int cpu_enable_trap_ctr_access(void *__unused) 
	return 0;

}



atomic_t arm64_el2_vector_last_slot = ATOMIC_INIT(-1);



#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR

#include <asm/mmu_context.h>

#include <asm/cacheflush.h>
@@ -90,7 +92,6 @@ static void __install_bp_hardening_cb(bp_hardening_cb_t fn, 
				      const char *hyp_vecs_start,

				      const char *hyp_vecs_end)

{

	static int last_slot = -1;

	static DEFINE_SPINLOCK(bp_lock);

	int cpu, slot = -1;
@@ -103,10 +104,8 @@ static void __install_bp_hardening_cb(bp_hardening_cb_t fn, 
	}



	if (slot == -1) {

		last_slot++;

		BUG_ON(((__bp_harden_hyp_vecs_end - __bp_harden_hyp_vecs_start)

			/ SZ_2K) <= last_slot);

		slot = last_slot;

		slot = atomic_inc_return(&arm64_el2_vector_last_slot);

		BUG_ON(slot >= BP_HARDEN_EL2_SLOTS);

		__copy_hyp_vect_bpi(slot, hyp_vecs_start, hyp_vecs_end);

	}