4.9-stable review patch. If anyone has any objections, please let me know.
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From: Russell King rmk+kernel@armlinux.org.uk
Commit c44f366ea7c85e1be27d08f2f0880f4120698125 upstream.
Warn at error level if the context switching function is not what we are expecting. This can happen with big.Little systems, which we currently do not support.
Signed-off-by: Russell King rmk+kernel@armlinux.org.uk Boot-tested-by: Tony Lindgren tony@atomide.com Reviewed-by: Tony Lindgren tony@atomide.com Acked-by: Marc Zyngier marc.zyngier@arm.com Signed-off-by: David A. Long dave.long@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm/mm/proc-v7-bugs.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
--- a/arch/arm/mm/proc-v7-bugs.c +++ b/arch/arm/mm/proc-v7-bugs.c @@ -12,6 +12,8 @@ #ifdef CONFIG_HARDEN_BRANCH_PREDICTOR DEFINE_PER_CPU(harden_branch_predictor_fn_t, harden_branch_predictor_fn);
+extern void cpu_v7_iciallu_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm); +extern void cpu_v7_bpiall_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm); extern void cpu_v7_smc_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm); extern void cpu_v7_hvc_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
@@ -50,6 +52,8 @@ static void cpu_v7_spectre_init(void) case ARM_CPU_PART_CORTEX_A17: case ARM_CPU_PART_CORTEX_A73: case ARM_CPU_PART_CORTEX_A75: + if (processor.switch_mm != cpu_v7_bpiall_switch_mm) + goto bl_error; per_cpu(harden_branch_predictor_fn, cpu) = harden_branch_predictor_bpiall; spectre_v2_method = "BPIALL"; @@ -57,6 +61,8 @@ static void cpu_v7_spectre_init(void)
case ARM_CPU_PART_CORTEX_A15: case ARM_CPU_PART_BRAHMA_B15: + if (processor.switch_mm != cpu_v7_iciallu_switch_mm) + goto bl_error; per_cpu(harden_branch_predictor_fn, cpu) = harden_branch_predictor_iciallu; spectre_v2_method = "ICIALLU"; @@ -82,6 +88,8 @@ static void cpu_v7_spectre_init(void) ARM_SMCCC_ARCH_WORKAROUND_1, &res); if ((int)res.a0 != 0) break; + if (processor.switch_mm != cpu_v7_hvc_switch_mm && cpu) + goto bl_error; per_cpu(harden_branch_predictor_fn, cpu) = call_hvc_arch_workaround_1; processor.switch_mm = cpu_v7_hvc_switch_mm; @@ -93,6 +101,8 @@ static void cpu_v7_spectre_init(void) ARM_SMCCC_ARCH_WORKAROUND_1, &res); if ((int)res.a0 != 0) break; + if (processor.switch_mm != cpu_v7_smc_switch_mm && cpu) + goto bl_error; per_cpu(harden_branch_predictor_fn, cpu) = call_smc_arch_workaround_1; processor.switch_mm = cpu_v7_smc_switch_mm; @@ -109,6 +119,11 @@ static void cpu_v7_spectre_init(void) if (spectre_v2_method) pr_info("CPU%u: Spectre v2: using %s workaround\n", smp_processor_id(), spectre_v2_method); + return; + +bl_error: + pr_err("CPU%u: Spectre v2: incorrect context switching function, system vulnerable\n", + cpu); } #else static void cpu_v7_spectre_init(void)