[PATCH v7 23/33] arm64: kaslr: Use feature override instead of parsing the cmdline again

[Ard Biesheuvel]

The early kaslr code open codes the detection of 'nokaslr' on the kernel
command line, which is no longer necessary now that the feature
detection code, which also looks for the same string, executes before
this code.

Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
---
 arch/arm64/kernel/pi/kaslr_early.c | 54 +-------------------
 1 file changed, 2 insertions(+), 52 deletions(-)

diff --git a/arch/arm64/kernel/pi/kaslr_early.c b/arch/arm64/kernel/pi/kaslr_early.c
index 86ae0273c95016c6..934e95fbd4278d0b 100644
--- a/arch/arm64/kernel/pi/kaslr_early.c
+++ b/arch/arm64/kernel/pi/kaslr_early.c
@@ -15,57 +15,6 @@
 #include <asm/archrandom.h>
 #include <asm/memory.h>
 
-/* taken from lib/string.c */
-static char *__init __strstr(const char *s1, const char *s2)
-{
-	size_t l1, l2;
-
-	l2 = strlen(s2);
-	if (!l2)
-		return (char *)s1;
-	l1 = strlen(s1);
-	while (l1 >= l2) {
-		l1--;
-		if (!memcmp(s1, s2, l2))
-			return (char *)s1;
-		s1++;
-	}
-	return NULL;
-}
-static bool __init cmdline_contains_nokaslr(const u8 *cmdline)
-{
-	const u8 *str;
-
-	str = __strstr(cmdline, "nokaslr");
-	return str == cmdline || (str > cmdline && *(str - 1) == ' ');
-}
-
-static bool __init 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);
-}
-
 static u64 __init get_kaslr_seed(void *fdt)
 {
 	static char const chosen_str[] __initconst = "chosen";
@@ -91,7 +40,8 @@ asmlinkage u64 __init kaslr_early_init(void *fdt)
 {
 	u64 seed;
 
-	if (is_kaslr_disabled_cmdline(fdt))
+	if (cpuid_feature_extract_unsigned_field(arm64_sw_feature_override.val,
+						 ARM64_SW_FEATURE_OVERRIDE_NOKASLR))
 		return 0;
 
 	seed = get_kaslr_seed(fdt);
-- 
2.35.1