[PATCH v7 19/23] arm64: Move "nokaslr" over to the early cpufeature infrastructure

Marc Zyngier
2021-02-08T10:22:27Z

Given that the early cpufeature infrastructure has borrowed quite
a lot of code from the kaslr implementation, let's reimplement
the matching of the "nokaslr" option with it.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
---
arch/arm64/kernel/idreg-override.c | 15 +++++++++++++
arch/arm64/kernel/kaslr.c | 36 ++----------------------------
2 files changed, 17 insertions(+), 34 deletions(-)

diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index b994d689d6fb..70dd70eee7a2 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -37,8 +37,22 @@ static const struct ftr_set_desc mmfr1 __initconst = {
},
};

+extern struct arm64_ftr_override kaslr_feature_override;
+
+static const struct ftr_set_desc kaslr __initconst = {
+ .name = "kaslr",
+#ifdef CONFIG_RANDOMIZE_BASE
+ .override = &kaslr_feature_override,
+#endif
+ .fields = {
+ { "disabled", 0 },
+ {}
+ },
+};
+
static const struct ftr_set_desc * const regs[] __initconst = {
&mmfr1,
+ &kaslr,
};

static const struct {
@@ -47,6 +61,7 @@ static const struct {
} aliases[] __initconst = {
{ "kvm-arm.mode=nvhe", "id_aa64mmfr1.vh=0" },
{ "kvm-arm.mode=protected", "id_aa64mmfr1.vh=0" },
+ { "nokaslr", "kaslr.disabled=1" },
};

static int __init find_field(const char *cmdline,
diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index 5fc86e7d01a1..27f8939deb1b 100644
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -51,39 +51,7 @@ static __init u64 get_kaslr_seed(void *fdt)
return ret;
}

-static __init bool cmdline_contains_nokaslr(const u8 *cmdline)
-{
- const u8 *str;
-
- str = strstr(cmdline, "nokaslr");
- return str == cmdline || (str > cmdline && *(str - 1) == ' ');
-}
-
-static __init bool is_kaslr_disabled_cmdline(void *fdt)
-{
- if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) {
- int node;
- const u8 *prop;
-
- node = fdt_path_offset(fdt, "/chosen");
- if (node < 0)
- goto out;
-
- prop = fdt_getprop(fdt, node, "bootargs", NULL);
- if (!prop)
- goto out;
-
- if (cmdline_contains_nokaslr(prop))
- return true;
-
- if (IS_ENABLED(CONFIG_CMDLINE_EXTEND))
- goto out;
-
- return false;
- }
-out:
- return cmdline_contains_nokaslr(CONFIG_CMDLINE);
-}
+struct arm64_ftr_override kaslr_feature_override __initdata;

/*
* This routine will be executed with the kernel mapped at its default virtual
@@ -126,7 +94,7 @@ u64 __init kaslr_early_init(void)
* Check if 'nokaslr' appears on the command line, and
* return 0 if that is the case.
*/
- if (is_kaslr_disabled_cmdline(fdt)) {
+ if (kaslr_feature_override.val & kaslr_feature_override.mask & 0xf) {
kaslr_status = KASLR_DISABLED_CMDLINE;
return 0;
}
--
2.29.2