Use PFR0 to identify need for mitigation of CVE-2017-5715
If the CSV2 field reads as 1 then branch targets trained in one
context cannot affect speculative execution in a different context.
In that case skip the workaround on Cortex A72 and A73.
Change-Id: Ide24fb6efc77c548e4296295adc38dca87d042ee
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>
diff --git a/lib/cpus/aarch64/cortex_a72.S b/lib/cpus/aarch64/cortex_a72.S
index 9633aa8..199820c 100644
--- a/lib/cpus/aarch64/cortex_a72.S
+++ b/lib/cpus/aarch64/cortex_a72.S
@@ -98,12 +98,16 @@
endfunc check_errata_859971
func check_errata_cve_2017_5715
+ cpu_check_csv2 x0, 1f
#if WORKAROUND_CVE_2017_5715
mov x0, #ERRATA_APPLIES
#else
mov x0, #ERRATA_MISSING
#endif
ret
+1:
+ mov x0, #ERRATA_NOT_APPLIES
+ ret
endfunc check_errata_cve_2017_5715
/* -------------------------------------------------
@@ -121,8 +125,10 @@
#endif
#if IMAGE_BL31 && WORKAROUND_CVE_2017_5715
+ cpu_check_csv2 x0, 1f
adr x0, workaround_mmu_runtime_exceptions
msr vbar_el3, x0
+1:
#endif
/* ---------------------------------------------
diff --git a/lib/cpus/aarch64/cortex_a73.S b/lib/cpus/aarch64/cortex_a73.S
index 11680a0..63d16f9 100644
--- a/lib/cpus/aarch64/cortex_a73.S
+++ b/lib/cpus/aarch64/cortex_a73.S
@@ -37,8 +37,10 @@
func cortex_a73_reset_func
#if IMAGE_BL31 && WORKAROUND_CVE_2017_5715
+ cpu_check_csv2 x0, 1f
adr x0, workaround_bpiall_vbar0_runtime_exceptions
msr vbar_el3, x0
+1:
#endif
/* ---------------------------------------------
@@ -115,12 +117,16 @@
endfunc cortex_a73_cluster_pwr_dwn
func check_errata_cve_2017_5715
+ cpu_check_csv2 x0, 1f
#if WORKAROUND_CVE_2017_5715
mov x0, #ERRATA_APPLIES
#else
mov x0, #ERRATA_MISSING
#endif
ret
+1:
+ mov x0, #ERRATA_NOT_APPLIES
+ ret
endfunc check_errata_cve_2017_5715
#if REPORT_ERRATA
diff --git a/lib/cpus/aarch64/cortex_a75.S b/lib/cpus/aarch64/cortex_a75.S
index 12ea304..d102795 100644
--- a/lib/cpus/aarch64/cortex_a75.S
+++ b/lib/cpus/aarch64/cortex_a75.S
@@ -12,15 +12,7 @@
func cortex_a75_reset_func
#if IMAGE_BL31 && WORKAROUND_CVE_2017_5715
- mrs x0, id_aa64pfr0_el1
- ubfx x0, x0, #ID_AA64PFR0_CSV2_SHIFT, #ID_AA64PFR0_CSV2_LENGTH
- /*
- * If the field equals to 1 then branch targets trained in one
- * context cannot affect speculative execution in a different context.
- */
- cmp x0, #1
- beq 1f
-
+ cpu_check_csv2 x0, 1f
adr x0, workaround_bpiall_vbar0_runtime_exceptions
msr vbar_el3, x0
1:
@@ -53,15 +45,7 @@
endfunc cortex_a75_reset_func
func check_errata_cve_2017_5715
- mrs x0, id_aa64pfr0_el1
- ubfx x0, x0, #ID_AA64PFR0_CSV2_SHIFT, #ID_AA64PFR0_CSV2_LENGTH
- /*
- * If the field equals to 1 then branch targets trained in one
- * context cannot affect speculative execution in a different context.
- */
- cmp x0, #1
- beq 1f
-
+ cpu_check_csv2 x0, 1f
#if WORKAROUND_CVE_2017_5715
mov x0, #ERRATA_APPLIES
#else