[PATCH v4 18/21] arm64: Move "nokaslr" over to the early cpufeature infrastructure

Marc Zyngier
2021-01-18T10:02:23Z

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>
---
arch/arm64/kernel/idreg-override.c | 17 ++++++++++++++
arch/arm64/kernel/kaslr.c | 37 +++---------------------------
2 files changed, 20 insertions(+), 34 deletions(-)

diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index 1db54878b2c4..143fe7b8e3ce 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -33,8 +33,24 @@ static const struct reg_desc mmfr1 __initdata = {
},
};

+extern u64 kaslr_feature_val;
+extern u64 kaslr_feature_mask;
+
+static const struct reg_desc kaslr __initdata = {
+ .name = "kaslr",
+#ifdef CONFIG_RANDOMIZE_BASE
+ .val = &kaslr_feature_val,
+ .mask = &kaslr_feature_mask,
+#endif
+ .fields = {
+ { "disabled", 0 },
+ {}
+ },
+};
+
static const struct reg_desc * const regs[] __initdata = {
&mmfr1,
+ &kaslr,
};

static const struct {
@@ -43,6 +59,7 @@ static const struct {
} aliases[] __initdata = {
{ "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, const struct reg_desc *reg,
diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index 5fc86e7d01a1..dcc4a5aadbe2 100644
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -51,39 +51,8 @@ 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);
-}
+u64 kaslr_feature_val __initdata;
+u64 kaslr_feature_mask __initdata;

/*
* This routine will be executed with the kernel mapped at its default virtual
@@ -126,7 +95,7 @@ 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_val & kaslr_feature_mask & 0xf) {
kaslr_status = KASLR_DISABLED_CMDLINE;
return 0;
}
--
2.29.2