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[108.26.179.17]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2c8f3b5ad36sm83217a91.26.2024.06.26.10.17.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Jun 2024 10:17:29 -0700 (PDT) From: Jesse Taube To: linux-riscv@lists.infradead.org Cc: Ard Biesheuvel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Jesse Taube , Alexandre Ghiti , Conor Dooley , Masahiro Yamada , Wende Tan , Christophe JAILLET , Sami Tolvanen , Andrew Morton , Baoquan He , Chen Jiahao , "Mike Rapoport (IBM)" , "Vishal Moola (Oracle)" , linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: [PATCH v2 3/3] RISC-V: Use Zkr to seed KASLR base address Date: Wed, 26 Jun 2024 13:16:52 -0400 Message-ID: <20240626171652.366415-3-jesse@rivosinc.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240626171652.366415-1-jesse@rivosinc.com> References: <20240626171652.366415-1-jesse@rivosinc.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Parse the device tree for Zkr in isa string. If Zkr is present, use it to seed the kernel base address. Signed-off-by: Jesse Taube --- arch/riscv/kernel/pi/Makefile | 2 +- arch/riscv/kernel/pi/archrandom_early.c | 30 ++++++++ arch/riscv/kernel/pi/fdt_early.c | 94 +++++++++++++++++++++++++ arch/riscv/kernel/pi/pi.h | 3 + arch/riscv/mm/init.c | 5 +- 5 files changed, 132 insertions(+), 2 deletions(-) create mode 100644 arch/riscv/kernel/pi/archrandom_early.c diff --git a/arch/riscv/kernel/pi/Makefile b/arch/riscv/kernel/pi/Makefile index 1ef7584be0c3..dba902f2a538 100644 --- a/arch/riscv/kernel/pi/Makefile +++ b/arch/riscv/kernel/pi/Makefile @@ -33,5 +33,5 @@ $(obj)/string.o: $(srctree)/lib/string.c FORCE $(obj)/ctype.o: $(srctree)/lib/ctype.c FORCE $(call if_changed_rule,cc_o_c) -obj-y := cmdline_early.pi.o fdt_early.pi.o string.pi.o ctype.pi.o lib-fdt.pi.o lib-fdt_ro.pi.o +obj-y := cmdline_early.pi.o fdt_early.pi.o string.pi.o ctype.pi.o lib-fdt.pi.o lib-fdt_ro.pi.o archrandom_early.pi.o extra-y := $(patsubst %.pi.o,%.o,$(obj-y)) diff --git a/arch/riscv/kernel/pi/archrandom_early.c b/arch/riscv/kernel/pi/archrandom_early.c new file mode 100644 index 000000000000..c6261165e8a6 --- /dev/null +++ b/arch/riscv/kernel/pi/archrandom_early.c @@ -0,0 +1,30 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include +#include + +#include "pi.h" + +/* + * To avoid rewriting code include asm/archrandom.h and create macros + * for the functions that won't be included. + */ +#undef riscv_has_extension_unlikely +#define riscv_has_extension_likely(...) false +#undef pr_err_once +#define pr_err_once(...) + +#include + +u64 get_kaslr_seed_zkr(const uintptr_t dtb_pa) +{ + unsigned long seed = 0; + + if (!early_isa_str((const void *)dtb_pa, "zkr")) + return 0; + + if (!csr_seed_long(&seed)) + return 0; + + return seed; +} diff --git a/arch/riscv/kernel/pi/fdt_early.c b/arch/riscv/kernel/pi/fdt_early.c index 40ee299702bf..ba76197b44d1 100644 --- a/arch/riscv/kernel/pi/fdt_early.c +++ b/arch/riscv/kernel/pi/fdt_early.c @@ -23,3 +23,97 @@ u64 get_kaslr_seed(uintptr_t dtb_pa) *prop = 0; return ret; } + +/* Based off of fdt_stringlist_contains */ +static int isa_string_contains(const char *strlist, int listlen, const char *str) +{ + int len = strlen(str); + const char *p; + + while (listlen >= len) { + if (strncasecmp(str, strlist, len) == 0) + return 1; + p = memchr(strlist, '_', listlen); + if (!p) + p = memchr(strlist, '\0', listlen); + if (!p) + return 0; /* malformed strlist.. */ + listlen -= (p - strlist) + 1; + strlist = p + 1; + } + + return 0; +} + +/* Based off of fdt_nodename_eq_ */ +static int fdt_node_name_eq(const void *fdt, int offset, + const char *s) +{ + int olen; + int len = strlen(s); + const char *p = fdt_get_name(fdt, offset, &olen); + + if (!p || olen < len) + /* short match */ + return 0; + + if (memcmp(p, s, len) != 0) + return 0; + + if (p[len] == '\0') + return 1; + else if (!memchr(s, '@', len) && (p[len] == '@')) + return 1; + else + return 0; +} + +/* + * Returns true if the extension is in the isa string + * Returns false if the extension is not found + */ +static bool get_ext_named(const void *fdt, int node, const char *name) +{ + const void *prop; + int len; + + prop = fdt_getprop(fdt, node, "riscv,isa-base", &len); + if (prop && isa_string_contains(prop, len, name)) + return true; + + prop = fdt_getprop(fdt, node, "riscv,isa-extensions", &len); + if (prop && isa_string_contains(prop, len, name)) + return true; + + prop = fdt_getprop(fdt, node, "riscv,isa", &len); + if (prop && isa_string_contains(prop, len, name)) + return true; + + return false; +} + +/* + * Returns true if the extension is in the isa string on all cpus + * Returns false if the extension is not found + */ +bool early_isa_str(const void *fdt, const char *ext_name) +{ + int node, parent; + bool ret = false; + + parent = fdt_path_offset(fdt, "/cpus"); + if (parent < 0) + return false; + + fdt_for_each_subnode(node, fdt, parent) { + if (!fdt_node_name_eq(fdt, node, "cpu")) + continue; + + if (!get_ext_named(fdt, node, ext_name)) + return false; + + ret = true; + } + + return ret; +} diff --git a/arch/riscv/kernel/pi/pi.h b/arch/riscv/kernel/pi/pi.h index 65da99466baf..26e7e5f84a30 100644 --- a/arch/riscv/kernel/pi/pi.h +++ b/arch/riscv/kernel/pi/pi.h @@ -4,6 +4,8 @@ #include +bool early_isa_str(const void *fdt, const char *ext_name); + /* * The folowing functions are exported (but prefixed) declare them here so * that LLVM does not complain it lacks the 'static' keyword (which, if @@ -11,6 +13,7 @@ */ u64 get_kaslr_seed(uintptr_t dtb_pa); +u64 get_kaslr_seed_zkr(const uintptr_t dtb_pa); bool set_nokaslr_from_cmdline(uintptr_t dtb_pa); u64 set_satp_mode_from_cmdline(uintptr_t dtb_pa); diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 9940171c79f0..bfb068dc4a64 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -1025,6 +1025,7 @@ static void __init pt_ops_set_late(void) #ifdef CONFIG_RANDOMIZE_BASE extern bool __init __pi_set_nokaslr_from_cmdline(uintptr_t dtb_pa); extern u64 __init __pi_get_kaslr_seed(uintptr_t dtb_pa); +extern u64 __init __pi_get_kaslr_seed_zkr(const uintptr_t dtb_pa); static int __init print_nokaslr(char *p) { @@ -1045,10 +1046,12 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa) #ifdef CONFIG_RANDOMIZE_BASE if (!__pi_set_nokaslr_from_cmdline(dtb_pa)) { - u64 kaslr_seed = __pi_get_kaslr_seed(dtb_pa); + u64 kaslr_seed = __pi_get_kaslr_seed_zkr(dtb_pa); u32 kernel_size = (uintptr_t)(&_end) - (uintptr_t)(&_start); u32 nr_pos; + if (kaslr_seed == 0) + kaslr_seed = __pi_get_kaslr_seed(dtb_pa); /* * Compute the number of positions available: we are limited * by the early page table that only has one PUD and we must -- 2.45.2