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

Author: samitolvanen

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);

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));

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);

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));

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);
 

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));