arm64: Implement branch predictor hardening for Falkor

Falkor is susceptible to branch predictor aliasing and can
theoretically be attacked by malicious code. This patch
implements a mitigation for these attacks, preventing any
malicious entries from affecting other victim contexts.

Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
[will: fix label name when !CONFIG_KVM and remove references to MIDR_FALKOR]
Signed-off-by: Will Deacon <will.deacon@arm.com>

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Shanker Donthineni
2018-01-05 14:28:59 -06:00
committed by Catalin Marinas
parent aa6acde65e
commit ec82b567a7
6 changed files with 70 additions and 3 deletions

View File

@@ -54,6 +54,8 @@ DEFINE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data);
#ifdef CONFIG_KVM
extern char __psci_hyp_bp_inval_start[], __psci_hyp_bp_inval_end[];
extern char __qcom_hyp_sanitize_link_stack_start[];
extern char __qcom_hyp_sanitize_link_stack_end[];
static void __copy_hyp_vect_bpi(int slot, const char *hyp_vecs_start,
const char *hyp_vecs_end)
@@ -96,8 +98,10 @@ static void __install_bp_hardening_cb(bp_hardening_cb_t fn,
spin_unlock(&bp_lock);
}
#else
#define __psci_hyp_bp_inval_start NULL
#define __psci_hyp_bp_inval_end NULL
#define __psci_hyp_bp_inval_start NULL
#define __psci_hyp_bp_inval_end NULL
#define __qcom_hyp_sanitize_link_stack_start NULL
#define __qcom_hyp_sanitize_link_stack_end NULL
static void __install_bp_hardening_cb(bp_hardening_cb_t fn,
const char *hyp_vecs_start,
@@ -138,6 +142,29 @@ static int enable_psci_bp_hardening(void *data)
return 0;
}
static void qcom_link_stack_sanitization(void)
{
u64 tmp;
asm volatile("mov %0, x30 \n"
".rept 16 \n"
"bl . + 4 \n"
".endr \n"
"mov x30, %0 \n"
: "=&r" (tmp));
}
static int qcom_enable_link_stack_sanitization(void *data)
{
const struct arm64_cpu_capabilities *entry = data;
install_bp_hardening_cb(entry, qcom_link_stack_sanitization,
__qcom_hyp_sanitize_link_stack_start,
__qcom_hyp_sanitize_link_stack_end);
return 0;
}
#endif /* CONFIG_HARDEN_BRANCH_PREDICTOR */
#define MIDR_RANGE(model, min, max) \
@@ -302,6 +329,15 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
MIDR_ALL_VERSIONS(MIDR_CORTEX_A75),
.enable = enable_psci_bp_hardening,
},
{
.capability = ARM64_HARDEN_BRANCH_PREDICTOR,
MIDR_ALL_VERSIONS(MIDR_QCOM_FALKOR_V1),
.enable = qcom_enable_link_stack_sanitization,
},
{
.capability = ARM64_HARDEN_BP_POST_GUEST_EXIT,
MIDR_ALL_VERSIONS(MIDR_QCOM_FALKOR_V1),
},
#endif
{
}