lib: cpus: sanity check pointers before use

The cpu_ops structure contains a lot of function pointers. It
is a good idea to verify that the function pointer is not NULL
before executing it.

This patch sanity checks each pointer before use to prevent any
unforeseen crashes. These checks have been enabled for debug
builds only.

Change-Id: Ib208331c20e60f0c7c582a20eb3d8cc40fb99d21
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>

diff --git a/lib/cpus/aarch64/cpu_helpers.S b/lib/cpus/aarch64/cpu_helpers.S
index 808c7f807a519dbb26af4faaf878542b5d854a94..da663be0e0a4fd2922fa6a814eab2c32c5ebc3d3 100644 (file)
--- a/lib/cpus/aarch64/cpu_helpers.S
+++ b/lib/cpus/aarch64/cpu_helpers.S
@@ -78,6 +78,10 @@ func prepare_cpu_pwr_dwn
        mov     x1, #CPU_PWR_DWN_OPS
        add     x1, x1, x2, lsl #3
        ldr     x1, [x0, x1]
+#if ENABLE_ASSERTIONS
+       cmp     x1, #0
+       ASM_ASSERT(ne)
+#endif
        br      x1
 endfunc prepare_cpu_pwr_dwn
 
@@ -171,6 +175,10 @@ func get_cpu_ops_ptr
 
        /* Subtract the increment and offset to get the cpu-ops pointer */
        sub     x0, x4, #(CPU_OPS_SIZE + CPU_MIDR)
+#if ENABLE_ASSERTIONS
+       cmp     x0, #0
+       ASM_ASSERT(ne)
+#endif
 error_exit:
        ret
 endfunc get_cpu_ops_ptr
@@ -276,7 +284,15 @@ func print_errata_status
         * turn.
         */
        mrs     x0, tpidr_el3
+#if ENABLE_ASSERTIONS
+       cmp     x0, #0
+       ASM_ASSERT(ne)
+#endif
        ldr     x1, [x0, #CPU_DATA_CPU_OPS_PTR]
+#if ENABLE_ASSERTIONS
+       cmp     x1, #0
+       ASM_ASSERT(ne)
+#endif
        ldr     x0, [x1, #CPU_ERRATA_FUNC]
        cbz     x0, .Lnoprint
 
@@ -326,6 +342,10 @@ func check_wa_cve_2017_5715
        ASM_ASSERT(ne)
 #endif
        ldr     x0, [x0, #CPU_DATA_CPU_OPS_PTR]
+#if ENABLE_ASSERTIONS
+       cmp     x0, #0
+       ASM_ASSERT(ne)
+#endif
        ldr     x0, [x0, #CPU_EXTRA1_FUNC]
        /*
         * If the reserved function pointer is NULL, this CPU
@@ -359,6 +379,10 @@ func wa_cve_2018_3639_get_disable_ptr
        ASM_ASSERT(ne)
 #endif
        ldr     x0, [x0, #CPU_DATA_CPU_OPS_PTR]
+#if ENABLE_ASSERTIONS
+       cmp     x0, #0
+       ASM_ASSERT(ne)
+#endif
        ldr     x0, [x0, #CPU_EXTRA2_FUNC]
        ret
 endfunc wa_cve_2018_3639_get_disable_ptr