Implement static workaround for CVE-2018-3639

For affected CPUs, this approach enables the mitigation during EL3
initialization, following every PE reset. No mechanism is provided to
disable the mitigation at runtime.

This approach permanently mitigates the entire software stack and no
additional mitigation code is required in other software components.

TF-A implements this approach for the following affected CPUs:

*   Cortex-A57 and Cortex-A72, by setting bit 55 (Disable load pass store) of
    `CPUACTLR_EL1` (`S3_1_C15_C2_0`).

*   Cortex-A73, by setting bit 3 of `S3_0_C15_C0_0` (not documented in the
    Technical Reference Manual (TRM)).

*   Cortex-A75, by setting bit 35 (reserved in TRM) of `CPUACTLR_EL1`
    (`S3_0_C15_C1_0`).

Additionally, a new SMC interface is implemented to allow software
executing in lower ELs to discover whether the system is mitigated
against CVE-2018-3639.

Refer to "Firmware interfaces for mitigating cache speculation
vulnerabilities System Software on Arm Systems"[0] for more
information.

[0] https://developer.arm.com/cache-speculation-vulnerability-firmware-specification

Change-Id: I084aa7c3bc7c26bf2df2248301270f77bed22ceb
Signed-off-by: Dimitris Papastamos <[email protected]>

diff --git a/docs/cpu-specific-build-macros.rst b/docs/cpu-specific-build-macros.rst
index 65f6adb8d18730e0f68536f11d0f405f787e87a0..a89305b7d2b502ace5e2a928c13de35bd628c513 100644 (file)
--- a/docs/cpu-specific-build-macros.rst
+++ b/docs/cpu-specific-build-macros.rst
@@ -24,6 +24,12 @@ vulnerability workarounds should be applied at runtime.
    with the recommendation in the spec regarding workaround discovery.
    Defaults to 1.
 
+-  ``WORKAROUND_CVE_2018_3639``: Enables the security workaround for
+   `CVE-2018-3639`_. Defaults to 1. The TF-A project recommends to keep
+   the default value of 1 even on platforms that are unaffected by
+   CVE-2018-3639, in order to comply with the recommendation in the spec
+   regarding workaround discovery.
+
 CPU Errata Workarounds
 ----------------------
 

diff --git a/include/lib/cpus/aarch64/cortex_a57.h b/include/lib/cpus/aarch64/cortex_a57.h
index 6c45c06693e18495567344e859978bec596099a4..83ec934267b07f0861552bb378c1183283950b23 100644 (file)
--- a/include/lib/cpus/aarch64/cortex_a57.h
+++ b/include/lib/cpus/aarch64/cortex_a57.h
@@ -44,6 +44,7 @@
 #define CORTEX_A57_CPUACTLR_EL1                                S3_1_C15_C2_0
 
 #define CORTEX_A57_CPUACTLR_EL1_DIS_LOAD_PASS_DMB      (ULL(1) << 59)
+#define CORTEX_A57_CPUACTLR_EL1_DIS_LOAD_PASS_STORE    (ULL(1) << 55)
 #define CORTEX_A57_CPUACTLR_EL1_GRE_NGRE_AS_NGNRE      (ULL(1) << 54)
 #define CORTEX_A57_CPUACTLR_EL1_DIS_OVERREAD           (ULL(1) << 52)
 #define CORTEX_A57_CPUACTLR_EL1_NO_ALLOC_WBWA          (ULL(1) << 49)

diff --git a/include/lib/cpus/aarch64/cortex_a72.h b/include/lib/cpus/aarch64/cortex_a72.h
index 6fbb707605507b05f1cd4c6c26ee29219757ec74..9f1847061ded40eefdd9610cfbca90227c9d26ab 100644 (file)
--- a/include/lib/cpus/aarch64/cortex_a72.h
+++ b/include/lib/cpus/aarch64/cortex_a72.h
@@ -32,6 +32,7 @@
 #define CORTEX_A72_CPUACTLR_EL1                                        S3_1_C15_C2_0
 
 #define CORTEX_A72_CPUACTLR_EL1_DISABLE_L1_DCACHE_HW_PFTCH     (ULL(1) << 56)
+#define CORTEX_A72_CPUACTLR_EL1_DIS_LOAD_PASS_STORE            (ULL(1) << 55)
 #define CORTEX_A72_CPUACTLR_EL1_NO_ALLOC_WBWA                  (ULL(1) << 49)
 #define CORTEX_A72_CPUACTLR_EL1_DCC_AS_DCCI                    (ULL(1) << 44)
 #define CORTEX_A72_CPUACTLR_EL1_DIS_INSTR_PREFETCH             (ULL(1) << 32)

diff --git a/include/lib/cpus/aarch64/cortex_a73.h b/include/lib/cpus/aarch64/cortex_a73.h
index faff5fef65b974178164f5ae95a1e9ef31ac2838..4db0cae231563e730ce33d123dc6866d9aa345b0 100644 (file)
--- a/include/lib/cpus/aarch64/cortex_a73.h
+++ b/include/lib/cpus/aarch64/cortex_a73.h
@@ -22,4 +22,11 @@
  ******************************************************************************/
 #define CORTEX_A73_L2MERRSR_EL1                S3_1_C15_C2_3   /* Instruction def. */
 
+/*******************************************************************************
+ * CPU implementation defined register specific definitions.
+ ******************************************************************************/
+#define CORTEX_A73_IMP_DEF_REG1                S3_0_C15_C0_0
+
+#define CORTEX_A73_IMP_DEF_REG1_DISABLE_LOAD_PASS_STORE        (1 << 3)
+
 #endif /* __CORTEX_A73_H__ */

diff --git a/include/lib/cpus/aarch64/cortex_a75.h b/include/lib/cpus/aarch64/cortex_a75.h
index 20f02518aa8a01af6837b23677c1fa738ee5e63b..493c7d4728beeee60e6738a7fe36eef304cbce0a 100644 (file)
--- a/include/lib/cpus/aarch64/cortex_a75.h
+++ b/include/lib/cpus/aarch64/cortex_a75.h
@@ -16,6 +16,13 @@
 #define CORTEX_A75_CPUPWRCTLR_EL1      S3_0_C15_C2_7
 #define CORTEX_A75_CPUECTLR_EL1                S3_0_C15_C1_4
 
+/*******************************************************************************
+ * CPU Auxiliary Control register specific definitions.
+ ******************************************************************************/
+#define CORTEX_A75_CPUACTLR_EL1                S3_0_C15_C1_0
+
+#define CORTEX_A75_CPUACTLR_EL1_DISABLE_LOAD_PASS_STORE        (1 << 35)
+
 /* Definitions of register field mask in CORTEX_A75_CPUPWRCTLR_EL1 */
 #define CORTEX_A75_CORE_PWRDN_EN_MASK  0x1
 

diff --git a/include/services/arm_arch_svc.h b/include/services/arm_arch_svc.h
index 29616013a8f9c9e66f3dcccb6c46a56e6cd582dc..0d2f47745951a97a28eaef6a0c21e142e590a6a1 100644 (file)
--- a/include/services/arm_arch_svc.h
+++ b/include/services/arm_arch_svc.h
@@ -10,5 +10,8 @@
 #define SMCCC_VERSION                  U(0x80000000)
 #define SMCCC_ARCH_FEATURES            U(0x80000001)
 #define SMCCC_ARCH_WORKAROUND_1                U(0x80008000)
+#define SMCCC_ARCH_WORKAROUND_2                U(0x80007FFF)
+
+#define SMCCC_ARCH_NOT_REQUIRED                -2
 
 #endif /* __ARM_ARCH_SVC_H__ */

diff --git a/lib/cpus/aarch64/cortex_a57.S b/lib/cpus/aarch64/cortex_a57.S
index 8470c6c5f7030f6003380ebbb196b6858ece3027..721bb49abfc01c6dc2d3a24739a00cdbc2e0ecdd 100644 (file)
--- a/lib/cpus/aarch64/cortex_a57.S
+++ b/lib/cpus/aarch64/cortex_a57.S
@@ -337,6 +337,15 @@ func check_errata_cve_2017_5715
        ret
 endfunc check_errata_cve_2017_5715
 
+func check_errata_cve_2018_3639
+#if WORKAROUND_CVE_2018_3639
+       mov     x0, #ERRATA_APPLIES
+#else
+       mov     x0, #ERRATA_MISSING
+#endif
+       ret
+endfunc check_errata_cve_2018_3639
+
        /* -------------------------------------------------
         * The CPU Ops reset function for Cortex-A57.
         * Shall clobber: x0-x19
@@ -397,6 +406,14 @@ func cortex_a57_reset_func
        msr     vbar_el3, x0
 #endif
 
+#if WORKAROUND_CVE_2018_3639
+       mrs     x0, CORTEX_A57_CPUACTLR_EL1
+       orr     x0, x0, #CORTEX_A57_CPUACTLR_EL1_DIS_LOAD_PASS_STORE
+       msr     CORTEX_A57_CPUACTLR_EL1, x0
+       isb
+       dsb     sy
+#endif
+
        /* ---------------------------------------------
         * Enable the SMP bit.
         * ---------------------------------------------
@@ -528,6 +545,7 @@ func cortex_a57_errata_report
        report_errata ERRATA_A57_833471, cortex_a57, 833471
        report_errata ERRATA_A57_859972, cortex_a57, 859972
        report_errata WORKAROUND_CVE_2017_5715, cortex_a57, cve_2017_5715
+       report_errata WORKAROUND_CVE_2018_3639, cortex_a57, cve_2018_3639
 
        ldp     x8, x30, [sp], #16
        ret

diff --git a/lib/cpus/aarch64/cortex_a72.S b/lib/cpus/aarch64/cortex_a72.S
index b67c987763b51090a4ada8bd80dd6890d59aecc5..6ef35cfcfe6d1f5f9546d54faa3d3e310f29643f 100644 (file)
--- a/lib/cpus/aarch64/cortex_a72.S
+++ b/lib/cpus/aarch64/cortex_a72.S
@@ -110,6 +110,15 @@ func check_errata_cve_2017_5715
        ret
 endfunc check_errata_cve_2017_5715
 
+func check_errata_cve_2018_3639
+#if WORKAROUND_CVE_2018_3639
+       mov     x0, #ERRATA_APPLIES
+#else
+       mov     x0, #ERRATA_MISSING
+#endif
+       ret
+endfunc check_errata_cve_2018_3639
+
        /* -------------------------------------------------
         * The CPU Ops reset function for Cortex-A72.
         * -------------------------------------------------
@@ -131,6 +140,14 @@ func cortex_a72_reset_func
 1:
 #endif
 
+#if WORKAROUND_CVE_2018_3639
+       mrs     x0, CORTEX_A72_CPUACTLR_EL1
+       orr     x0, x0, #CORTEX_A72_CPUACTLR_EL1_DIS_LOAD_PASS_STORE
+       msr     CORTEX_A72_CPUACTLR_EL1, x0
+       isb
+       dsb     sy
+#endif
+
        /* ---------------------------------------------
         * Enable the SMP bit.
         * ---------------------------------------------
@@ -265,6 +282,7 @@ func cortex_a72_errata_report
         */
        report_errata ERRATA_A72_859971, cortex_a72, 859971
        report_errata WORKAROUND_CVE_2017_5715, cortex_a72, cve_2017_5715
+       report_errata WORKAROUND_CVE_2018_3639, cortex_a72, cve_2018_3639
 
        ldp     x8, x30, [sp], #16
        ret

diff --git a/lib/cpus/aarch64/cortex_a73.S b/lib/cpus/aarch64/cortex_a73.S
index c66067d70e9faa1426fade7e6dc8120e16bb9492..2dbd515f89a82384243ae70a5412b6ea8d79a5ef 100644 (file)
--- a/lib/cpus/aarch64/cortex_a73.S
+++ b/lib/cpus/aarch64/cortex_a73.S
@@ -43,6 +43,13 @@ func cortex_a73_reset_func
 1:
 #endif
 
+#if WORKAROUND_CVE_2018_3639
+       mrs     x0, CORTEX_A73_IMP_DEF_REG1
+       orr     x0, x0, #CORTEX_A73_IMP_DEF_REG1_DISABLE_LOAD_PASS_STORE
+       msr     CORTEX_A73_IMP_DEF_REG1, x0
+       isb
+#endif
+
        /* ---------------------------------------------
         * Enable the SMP bit.
         * Clobbers : x0
@@ -129,6 +136,15 @@ func check_errata_cve_2017_5715
        ret
 endfunc check_errata_cve_2017_5715
 
+func check_errata_cve_2018_3639
+#if WORKAROUND_CVE_2018_3639
+       mov     x0, #ERRATA_APPLIES
+#else
+       mov     x0, #ERRATA_MISSING
+#endif
+       ret
+endfunc check_errata_cve_2018_3639
+
 #if REPORT_ERRATA
 /*
  * Errata printing function for Cortex A75. Must follow AAPCS.
@@ -144,6 +160,7 @@ func cortex_a73_errata_report
         * checking functions of each errata.
         */
        report_errata WORKAROUND_CVE_2017_5715, cortex_a73, cve_2017_5715
+       report_errata WORKAROUND_CVE_2018_3639, cortex_a73, cve_2018_3639
 
        ldp     x8, x30, [sp], #16
        ret

diff --git a/lib/cpus/aarch64/cortex_a75.S b/lib/cpus/aarch64/cortex_a75.S
index f92e4ed024ba7180697fbec77e3a03a20fbf1218..9cc2c01ed8005b1034011f6edbfb8d550d364b14 100644 (file)
--- a/lib/cpus/aarch64/cortex_a75.S
+++ b/lib/cpus/aarch64/cortex_a75.S
@@ -18,6 +18,13 @@ func cortex_a75_reset_func
 1:
 #endif
 
+#if WORKAROUND_CVE_2018_3639
+       mrs     x0, CORTEX_A75_CPUACTLR_EL1
+       orr     x0, x0, #CORTEX_A75_CPUACTLR_EL1_DISABLE_LOAD_PASS_STORE
+       msr     CORTEX_A75_CPUACTLR_EL1, x0
+       isb
+#endif
+
 #if ENABLE_AMU
        /* Make sure accesses from EL0/EL1 and EL2 are not trapped to EL3 */
        mrs     x0, actlr_el3
@@ -57,6 +64,15 @@ func check_errata_cve_2017_5715
        ret
 endfunc check_errata_cve_2017_5715
 
+func check_errata_cve_2018_3639
+#if WORKAROUND_CVE_2018_3639
+       mov     x0, #ERRATA_APPLIES
+#else
+       mov     x0, #ERRATA_MISSING
+#endif
+       ret
+endfunc check_errata_cve_2018_3639
+
        /* ---------------------------------------------
         * HW will do the cache maintenance while powering down
         * ---------------------------------------------
@@ -88,6 +104,7 @@ func cortex_a75_errata_report
         * checking functions of each errata.
         */
        report_errata WORKAROUND_CVE_2017_5715, cortex_a75, cve_2017_5715
+       report_errata WORKAROUND_CVE_2018_3639, cortex_a75, cve_2018_3639
 
        ldp     x8, x30, [sp], #16
        ret

diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 3ba8c1fcca5bf3fadcc3862f1183580abba4e7ce..31cd837be0f725fe1abf6a887d3956d38d04b131 100644 (file)
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -17,6 +17,7 @@ A53_DISABLE_NON_TEMPORAL_HINT ?=1
 A57_DISABLE_NON_TEMPORAL_HINT  ?=1
 
 WORKAROUND_CVE_2017_5715       ?=1
+WORKAROUND_CVE_2018_3639       ?=1
 
 # Process SKIP_A57_L1_FLUSH_PWR_DWN flag
 $(eval $(call assert_boolean,SKIP_A57_L1_FLUSH_PWR_DWN))
@@ -34,6 +35,10 @@ $(eval $(call add_define,A57_DISABLE_NON_TEMPORAL_HINT))
 $(eval $(call assert_boolean,WORKAROUND_CVE_2017_5715))
 $(eval $(call add_define,WORKAROUND_CVE_2017_5715))
 
+# Process WORKAROUND_CVE_2018_3639 flag
+$(eval $(call assert_boolean,WORKAROUND_CVE_2018_3639))
+$(eval $(call add_define,WORKAROUND_CVE_2018_3639))
+
 # CPU Errata Build flags.
 # These should be enabled by the platform if the erratum workaround needs to be
 # applied.

diff --git a/services/arm_arch_svc/arm_arch_svc_setup.c b/services/arm_arch_svc/arm_arch_svc_setup.c
index c357ebdb97adcd7704d7c2fa408932eb9dee133d..6089cf6ac8ba23300038c977746122f52427ad63 100644 (file)
--- a/services/arm_arch_svc/arm_arch_svc_setup.c
+++ b/services/arm_arch_svc/arm_arch_svc_setup.c
@@ -28,6 +28,10 @@ static int32_t smccc_arch_features(u_register_t arg)
                if (check_wa_cve_2017_5715() == ERRATA_NOT_APPLIES)
                        return 1;
                return 0; /* ERRATA_APPLIES || ERRATA_MISSING */
+#endif
+#if WORKAROUND_CVE_2018_3639
+       case SMCCC_ARCH_WORKAROUND_2:
+               return SMCCC_ARCH_NOT_REQUIRED;
 #endif
        default:
                return SMC_UNK;
@@ -59,6 +63,16 @@ static uintptr_t arm_arch_svc_smc_handler(uint32_t smc_fid,
                 * has no effect.
                 */
                SMC_RET0(handle);
+#endif
+#if WORKAROUND_CVE_2018_3639
+       case SMCCC_ARCH_WORKAROUND_2:
+               /*
+                * The workaround has already been applied on affected PEs
+                * requiring dynamic mitigation during entry to EL3.
+                * On unaffected or statically mitigated PEs, this function
+                * has no effect.
+                */
+               SMC_RET0(handle);
 #endif
        default:
                WARN("Unimplemented Arm Architecture Service Call: 0x%x \n",