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cpus: denver: Implement static workaround for CVE-2018-3639 

For Denver 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 EL3 software stack only. Other
software components are responsible to enable it for their exception
levels.

TF-A implements this approach for the Denver CPUs with DENVER_MIDR_PN3
and earlier:

*   By setting bit 11 (Disable speculative store buffering) of
    `ACTLR_EL3`

*   By setting bit 9 (Disable speculative memory disambiguation) of
    `ACTLR_EL3`

TF-A implements this approach for the Denver CPUs with DENVER_MIDR_PN4
and later:

*   By setting bit 18 (Disable speculative store buffering) of
    `ACTLR_EL3`

*   By setting bit 17 (Disable speculative memory disambiguation) of
    `ACTLR_EL3`

Change-Id: If1de96605ce3f7b0aff5fab2c828e5aecb687555
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
This commit is contained in:
Varun Wadekar 2018-08-28 09:11:30 -07:00
parent cf3ed0dcc7
commit 6cf8d65f27
2 changed files with 37 additions and 0 deletions
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8
include/lib/cpus/aarch64/denver.h
View File

@ -20,6 +20,14 @@
/* CPU state ids - implementation defined */
#define DENVER_CPU_STATE_POWER_DOWN U(0x3)
/* Speculative store buffering */
#define DENVER_CPU_DIS_SSB_EL3 (U(1) << 11)
#define DENVER_PN4_CPU_DIS_SSB_EL3 (U(1) << 18)
/* Speculative memory disambiguation */
#define DENVER_CPU_DIS_MD_EL3 (U(1) << 9)
#define DENVER_PN4_CPU_DIS_MD_EL3 (U(1) << 17)
/* Core power management states */
#define DENVER_CPU_PMSTATE_C1 U(0x1)
#define DENVER_CPU_PMSTATE_C6 U(0x6)

29
lib/cpus/aarch64/denver.S
View File

@ -211,6 +211,15 @@ 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 Denver.
* -------------------------------------------------
@ -236,6 +245,25 @@ func denver_reset_func
msr vbar_el3, x0
#endif
#if WORKAROUND_CVE_2018_3639
/*
* Denver CPUs with DENVER_MIDR_PN3 or earlier, use different
* bits in the ACTLR_EL3 register to disable speculative
* store buffer and memory disambiguation.
*/
mrs x0, midr_el1
mov_imm x1, DENVER_MIDR_PN4
cmp x0, x1
mrs x0, actlr_el3
mov x1, #(DENVER_CPU_DIS_MD_EL3 | DENVER_CPU_DIS_SSB_EL3)
mov x2, #(DENVER_PN4_CPU_DIS_MD_EL3 | DENVER_PN4_CPU_DIS_SSB_EL3)
csel x3, x1, x2, ne
orr x0, x0, x3
msr actlr_el3, x0
isb
dsb sy
#endif
/* ----------------------------------------------------
* Reset ACTLR.PMSTATE to C1 state
* ----------------------------------------------------
@ -294,6 +322,7 @@ func denver_errata_report
* checking functions of each errata.
*/
report_errata WORKAROUND_CVE_2017_5715, denver, cve_2017_5715
report_errata WORKAROUND_CVE_2018_3639, denver, cve_2018_3639
ldp x8, x30, [sp], #16
ret