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Date: Wed, 26 Jun 2024 13:16:52 -0400
From: Jesse Taube <jesse@...osinc.com>
To: linux-riscv@...ts.infradead.org
Cc: Ard Biesheuvel <ardb@...nel.org>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Bill Wendling <morbo@...gle.com>,
Justin Stitt <justinstitt@...gle.com>,
Jesse Taube <jesse@...osinc.com>,
Alexandre Ghiti <alexghiti@...osinc.com>,
Conor Dooley <conor.dooley@...rochip.com>,
Masahiro Yamada <masahiroy@...nel.org>,
Wende Tan <twd2.me@...il.com>,
Christophe JAILLET <christophe.jaillet@...adoo.fr>,
Sami Tolvanen <samitolvanen@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Baoquan He <bhe@...hat.com>,
Chen Jiahao <chenjiahao16@...wei.com>,
"Mike Rapoport (IBM)" <rppt@...nel.org>,
"Vishal Moola (Oracle)" <vishal.moola@...il.com>,
linux-kernel@...r.kernel.org,
llvm@...ts.linux.dev
Subject: [PATCH v2 3/3] RISC-V: Use Zkr to seed KASLR base address
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 <jesse@...osinc.com>
---
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 <asm/csr.h>
+#include <linux/processor.h>
+
+#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 <asm/archrandom.h>
+
+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 <linux/types.h>
+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
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