From: Yee Lee Date: Tue, 3 Aug 2021 07:08:22 +0000 (+0800) Subject: arm64/cpufeature: Optionally disable MTE via command-line X-Git-Tag: v5.15-rc1~145^2~2^2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7a062ce31807eb402c38edbec50c1b848b4298f3;p=thirdparty%2Flinux.git arm64/cpufeature: Optionally disable MTE via command-line MTE support needs to be optionally disabled in runtime for HW issue workaround, FW development and some evaluation works on system resource and performance. This patch makes two changes: (1) moves init of tag-allocation bits(ATA/ATA0) to cpu_enable_mte() as not cached in TLB. (2) allows ID_AA64PFR1_EL1.MTE to be overridden on its shadow value by giving "arm64.nomte" on cmdline. When the feature value is off, ATA and TCF will not set and the related functionalities are accordingly suppressed. Suggested-by: Catalin Marinas Suggested-by: Marc Zyngier Suggested-by: Suzuki K Poulose Signed-off-by: Yee Lee Link: https://lore.kernel.org/r/20210803070824.7586-2-yee.lee@mediatek.com Signed-off-by: Catalin Marinas --- diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index bdb22006f713f..6f257e39d89e7 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -380,6 +380,9 @@ arm64.nopauth [ARM64] Unconditionally disable Pointer Authentication support + arm64.nomte [ARM64] Unconditionally disable Memory Tagging Extension + support + ataflop= [HW,M68k] atarimouse= [HW,MOUSE] Atari Mouse diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index f6687f6f536b5..fc887399c68cd 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -699,8 +699,7 @@ (SCTLR_ELx_M | SCTLR_ELx_C | SCTLR_ELx_SA | SCTLR_EL1_SA0 | \ SCTLR_EL1_SED | SCTLR_ELx_I | SCTLR_EL1_DZE | SCTLR_EL1_UCT | \ SCTLR_EL1_NTWE | SCTLR_ELx_IESB | SCTLR_EL1_SPAN | SCTLR_ELx_ITFSB | \ - SCTLR_ELx_ATA | SCTLR_EL1_ATA0 | ENDIAN_SET_EL1 | SCTLR_EL1_UCI | \ - SCTLR_EL1_EPAN | SCTLR_EL1_RES1) + ENDIAN_SET_EL1 | SCTLR_EL1_UCI | SCTLR_EL1_EPAN | SCTLR_EL1_RES1) /* MAIR_ELx memory attributes (used by Linux) */ #define MAIR_ATTR_DEVICE_nGnRnE UL(0x00) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 0ead8bfedf201..51e6bf4bb7b5b 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1843,6 +1843,9 @@ static void bti_enable(const struct arm64_cpu_capabilities *__unused) #ifdef CONFIG_ARM64_MTE static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap) { + sysreg_clear_set(sctlr_el1, 0, SCTLR_ELx_ATA | SCTLR_EL1_ATA0); + isb(); + /* * Clear the tags in the zero page. This needs to be done via the * linear map which has the Tagged attribute. diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c index 53a381a7f65dd..d8e606fe3c21b 100644 --- a/arch/arm64/kernel/idreg-override.c +++ b/arch/arm64/kernel/idreg-override.c @@ -54,6 +54,7 @@ static const struct ftr_set_desc pfr1 __initconst = { .override = &id_aa64pfr1_override, .fields = { { "bt", ID_AA64PFR1_BT_SHIFT }, + { "mte", ID_AA64PFR1_MTE_SHIFT}, {} }, }; @@ -100,6 +101,7 @@ static const struct { { "arm64.nopauth", "id_aa64isar1.gpi=0 id_aa64isar1.gpa=0 " "id_aa64isar1.api=0 id_aa64isar1.apa=0" }, + { "arm64.nomte", "id_aa64pfr1.mte=0" }, { "nokaslr", "kaslr.disabled=1" }, };