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Commit c44f366e authored by Russell King's avatar Russell King
Browse files

ARM: spectre-v2: warn about incorrect context switching functions 



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: default avatarRussell King <rmk+kernel@armlinux.org.uk>
Boot-tested-by: default avatarTony Lindgren <tony@atomide.com>
Reviewed-by: default avatarTony Lindgren <tony@atomide.com>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent 10115105

arch/arm/mm/proc-v7-bugs.c

+15 −0
Original line number Diff line number Diff line
@@ -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)