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arm64: Make BP hardening slot counter available

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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: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Marc Zyngier 2018-03-13 12:40:39 +00:00
parent dc2e4633ff
commit 4205a89b80
3 changed files with 9 additions and 6 deletions
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3
arch/arm64/include/asm/mmu.h
View File

@ -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);

3
arch/arm64/kernel/bpi.S
View File

@ -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)

9
arch/arm64/kernel/cpu_errata.c
View File

@ -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);
}