arm64: use function_nocfi with __pa_symbol

With CONFIG_CFI_CLANG, the compiler replaces function address
references with the address of the function's CFI jump table
entry. This means that __pa_symbol(function) returns the physical
address of the jump table entry, which can lead to address space
confusion as the jump table points to the function's virtual
address. Therefore, use the function_nocfi() macro to ensure we are
always taking the address of the actual function instead.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210408182843.1754385-14-samitolvanen@google.com

diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index bd02e99..386b964 100644 (file)
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -140,7 +140,7 @@ static inline void cpu_replace_ttbr1(pgd_t *pgdp)
                ttbr1 |= TTBR_CNP_BIT;
        }
 
-       replace_phys = (void *)__pa_symbol(idmap_cpu_replace_ttbr1);
+       replace_phys = (void *)__pa_symbol(function_nocfi(idmap_cpu_replace_ttbr1));
 
        cpu_install_idmap();
        replace_phys(ttbr1);

diff --git a/arch/arm64/kernel/acpi_parking_protocol.c b/arch/arm64/kernel/acpi_parking_protocol.c
index e7c941d..bfeeb53 100644 (file)
--- a/arch/arm64/kernel/acpi_parking_protocol.c
+++ b/arch/arm64/kernel/acpi_parking_protocol.c
@@ -99,7 +99,8 @@ static int acpi_parking_protocol_cpu_boot(unsigned int cpu)
         * that read this address need to convert this address to the
         * Boot-Loader's endianness before jumping.
         */
-       writeq_relaxed(__pa_symbol(secondary_entry), &mailbox->entry_point);
+       writeq_relaxed(__pa_symbol(function_nocfi(secondary_entry)),
+                      &mailbox->entry_point);
        writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id);
 
        arch_send_wakeup_ipi_mask(cpumask_of(cpu));

diff --git a/arch/arm64/kernel/cpu-reset.h b/arch/arm64/kernel/cpu-reset.h
index ed50e95..f3adc57 100644 (file)
--- a/arch/arm64/kernel/cpu-reset.h
+++ b/arch/arm64/kernel/cpu-reset.h
@@ -22,7 +22,7 @@ static inline void __noreturn cpu_soft_restart(unsigned long entry,
 
        unsigned long el2_switch = !is_kernel_in_hyp_mode() &&
                is_hyp_mode_available();
-       restart = (void *)__pa_symbol(__cpu_soft_restart);
+       restart = (void *)__pa_symbol(function_nocfi(__cpu_soft_restart));
 
        cpu_install_idmap();
        restart(el2_switch, entry, arg0, arg1, arg2);

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index e5281e1..0b2e0d7 100644 (file)
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1462,7 +1462,7 @@ kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused)
        if (arm64_use_ng_mappings)
                return;
 
-       remap_fn = (void *)__pa_symbol(idmap_kpti_install_ng_mappings);
+       remap_fn = (void *)__pa_symbol(function_nocfi(idmap_kpti_install_ng_mappings));
 
        cpu_install_idmap();
        remap_fn(cpu, num_online_cpus(), __pa_symbol(swapper_pg_dir));

diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index 62d2bda..ab7f4c4 100644 (file)
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -38,7 +38,8 @@ static int __init cpu_psci_cpu_prepare(unsigned int cpu)
 
 static int cpu_psci_cpu_boot(unsigned int cpu)
 {
-       int err = psci_ops.cpu_on(cpu_logical_map(cpu), __pa_symbol(secondary_entry));
+       phys_addr_t pa_secondary_entry = __pa_symbol(function_nocfi(secondary_entry));
+       int err = psci_ops.cpu_on(cpu_logical_map(cpu), pa_secondary_entry);
        if (err)
                pr_err("failed to boot CPU%d (%d)\n", cpu, err);
 

diff --git a/arch/arm64/kernel/smp_spin_table.c b/arch/arm64/kernel/smp_spin_table.c
index 056772c..c45a835 100644 (file)
--- a/arch/arm64/kernel/smp_spin_table.c
+++ b/arch/arm64/kernel/smp_spin_table.c
@@ -66,6 +66,7 @@ static int smp_spin_table_cpu_init(unsigned int cpu)
 static int smp_spin_table_cpu_prepare(unsigned int cpu)
 {
        __le64 __iomem *release_addr;
+       phys_addr_t pa_holding_pen = __pa_symbol(function_nocfi(secondary_holding_pen));
 
        if (!cpu_release_addr[cpu])
                return -ENODEV;
@@ -88,7 +89,7 @@ static int smp_spin_table_cpu_prepare(unsigned int cpu)
         * boot-loader's endianness before jumping. This is mandated by
         * the boot protocol.
         */
-       writeq_relaxed(__pa_symbol(secondary_holding_pen), release_addr);
+       writeq_relaxed(pa_holding_pen, release_addr);
        __flush_dcache_area((__force void *)release_addr,
                            sizeof(*release_addr));