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Mon, 01 Feb 2021 12:04:18 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l6XwF-0006Hg-NK for linux-arm-kernel@lists.infradead.org; Mon, 01 Feb 2021 12:04:16 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4696164E8F; Mon, 1 Feb 2021 12:04:14 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1l6Xp9-00BG09-7b; Mon, 01 Feb 2021 11:56:55 +0000 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org Subject: [PATCH v6 12/21] arm64: cpufeature: Add an early command-line cpufeature override facility Date: Mon, 1 Feb 2021 11:56:28 +0000 Message-Id: <20210201115637.3123740-13-maz@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210201115637.3123740-1-maz@kernel.org> References: <20210201115637.3123740-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, dbrazdil@google.com, alexandru.elisei@arm.com, ardb@kernel.org, jingzhangos@google.com, pajay@qti.qualcomm.com, psodagud@codeaurora.org, sramana@codeaurora.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210201_070415_894201_99C423AA X-CRM114-Status: GOOD ( 24.43 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Jing Zhang , Prasad Sodagudi , Srinivas Ramana , Suzuki K Poulose , Catalin Marinas , Alexandru Elisei , James Morse , Ajay Patil , kernel-team@android.com, David Brazdil , Will Deacon , Ard Biesheuvel , Julien Thierry Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org In order to be able to override CPU features at boot time, let's add a command line parser that matches options of the form "cpureg.feature=value", and store the corresponding value into the override val/mask pair. No features are currently defined, so no expected change in functionality. Signed-off-by: Marc Zyngier Acked-by: David Brazdil Reviewed-by: Catalin Marinas --- arch/arm64/kernel/Makefile | 2 +- arch/arm64/kernel/head.S | 1 + arch/arm64/kernel/idreg-override.c | 164 +++++++++++++++++++++++++++++ 3 files changed, 166 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/kernel/idreg-override.c diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 86364ab6f13f..2262f0392857 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -17,7 +17,7 @@ obj-y := debug-monitors.o entry.o irq.o fpsimd.o \ return_address.o cpuinfo.o cpu_errata.o \ cpufeature.o alternative.o cacheinfo.o \ smp.o smp_spin_table.o topology.o smccc-call.o \ - syscall.o proton-pack.o + syscall.o proton-pack.o idreg-override.o targets += efi-entry.o diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index d74e5f84042e..3243e3ae9bd8 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -435,6 +435,7 @@ SYM_FUNC_START_LOCAL(__primary_switched) mov x0, x21 // pass FDT address in x0 bl early_fdt_map // Try mapping the FDT early + bl init_feature_override bl switch_to_vhe #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) bl kasan_early_init diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c new file mode 100644 index 000000000000..d8d0d3b25bc3 --- /dev/null +++ b/arch/arm64/kernel/idreg-override.c @@ -0,0 +1,164 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Early cpufeature override framework + * + * Copyright (C) 2020 Google LLC + * Author: Marc Zyngier + */ + +#include +#include +#include + +#include +#include + +#define FTR_DESC_NAME_LEN 20 +#define FTR_DESC_FIELD_LEN 10 + +struct ftr_set_desc { + char name[FTR_DESC_NAME_LEN]; + struct arm64_ftr_override *override; + struct { + char name[FTR_DESC_FIELD_LEN]; + u8 shift; + } fields[]; +}; + +static const struct ftr_set_desc * const regs[] __initconst = { +}; + +static char *cmdline_contains_option(const char *cmdline, const char *option) +{ + char *str = strstr(cmdline, option); + + if ((str == cmdline || (str > cmdline && isspace(*(str - 1))))) + return str; + + return NULL; +} + +static int __init find_field(const char *cmdline, + const struct ftr_set_desc *reg, int f, u64 *v) +{ + char opt[FTR_DESC_NAME_LEN + FTR_DESC_FIELD_LEN + 2], *str; + size_t len; + + snprintf(opt, ARRAY_SIZE(opt), "%s.%s=", reg->name, reg->fields[f].name); + + str = cmdline_contains_option(cmdline, opt); + if (!str) + return -1; + + str += strlen(opt); + len = strcspn(str, " "); + len = min(len, ARRAY_SIZE(opt) - 1); + strncpy(opt, str, len); + opt[len] = 0; + + return kstrtou64(opt, 0, v); +} + +static void __init match_options(const char *cmdline) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(regs); i++) { + int f; + + if (!regs[i]->override) + continue; + + for (f = 0; strlen(regs[i]->fields[f].name); f++) { + u64 shift = regs[i]->fields[f].shift; + u64 mask = 0xfUL << shift; + u64 v; + + if (find_field(cmdline, regs[i], f, &v)) + continue; + + regs[i]->override->val &= ~mask; + regs[i]->override->val |= (v << shift) & mask; + regs[i]->override->mask |= mask; + } + } +} + +static __init void __parse_cmdline(const char *cmdline) +{ + do { + char buf[256]; + size_t len; + int i; + + /* skip initial spaces */ + len = strspn(cmdline, " \t\n\v\f\r"); + cmdline += len; + + /* substring length */ + len = strcspn(cmdline, " \t\n\v\f\r"); + if (!len) + return; + + len = min(len, ARRAY_SIZE(buf) - 1); + strncpy(buf, cmdline, len); + buf[len] = 0; + + cmdline += len; + + match_options(buf); + + } while (1); +} + +static __init void parse_cmdline(void) +{ + if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) { + const u8 *prop; + void *fdt; + int node; + + fdt = get_early_fdt_ptr(); + if (!fdt) + goto out; + + node = fdt_path_offset(fdt, "/chosen"); + if (node < 0) + goto out; + + prop = fdt_getprop(fdt, node, "bootargs", NULL); + if (!prop) + goto out; + + __parse_cmdline(prop); + + if (!IS_ENABLED(CONFIG_CMDLINE_EXTEND)) + return; + } + +out: + __parse_cmdline(CONFIG_CMDLINE); +} + +/* Keep checkers quiet */ +void init_feature_override(void); + +asmlinkage void __init init_feature_override(void) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(regs); i++) { + if (regs[i]->override) { + regs[i]->override->val = 0; + regs[i]->override->mask = 0; + } + } + + parse_cmdline(); + + for (i = 0; i < ARRAY_SIZE(regs); i++) { + if (regs[i]->override) + __flush_dcache_area(regs[i]->override, + sizeof(*regs[i]->override)); + } +} -- 2.29.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel