linux-kernel - [PATCH 1/2] arm64: kaslr: Refactor early init command line parsing

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Message-Id: <20200921191557.350256-2-tyhicks@linux.microsoft.com>
Date:   Mon, 21 Sep 2020 14:15:56 -0500
From:   Tyler Hicks <tyhicks@...ux.microsoft.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>
Cc:     Pavel Tatashin <pasha.tatashin@...een.com>,
        Rob Herring <robh+dt@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] arm64: kaslr: Refactor early init command line parsing

Don't ask for *the* command line string to search for "nokaslr" in
kaslr_early_init(). Instead, tell a helper function to search all the
appropriate command line strings for "nokaslr" and return the result.

This paves the way for searching multiple command line strings without
having to concatenate the strings in early init.

Signed-off-by: Tyler Hicks <tyhicks@...ux.microsoft.com>
---
 arch/arm64/kernel/kaslr.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index b181e0544b79..4c779a67c2a6 100644
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -50,10 +50,16 @@ static __init u64 get_kaslr_seed(void *fdt)
 	return ret;
 }
 
-static __init const u8 *kaslr_get_cmdline(void *fdt)
+static __init bool cmdline_contains_nokaslr(const u8 *cmdline)
 {
-	static __initconst const u8 default_cmdline[] = CONFIG_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;
@@ -65,10 +71,10 @@ static __init const u8 *kaslr_get_cmdline(void *fdt)
 		prop = fdt_getprop(fdt, node, "bootargs", NULL);
 		if (!prop)
 			goto out;
-		return prop;
+		return cmdline_contains_nokaslr(prop);
 	}
 out:
-	return default_cmdline;
+	return cmdline_contains_nokaslr(CONFIG_CMDLINE);
 }
 
 /*
@@ -83,7 +89,6 @@ u64 __init kaslr_early_init(u64 dt_phys)
 {
 	void *fdt;
 	u64 seed, offset, mask, module_range;
-	const u8 *cmdline, *str;
 	unsigned long raw;
 	int size;
 
@@ -115,9 +120,7 @@ u64 __init kaslr_early_init(u64 dt_phys)
 	 * Check if 'nokaslr' appears on the command line, and
 	 * return 0 if that is the case.
 	 */
-	cmdline = kaslr_get_cmdline(fdt);
-	str = strstr(cmdline, "nokaslr");
-	if (str == cmdline || (str > cmdline && *(str - 1) == ' ')) {
+	if (is_kaslr_disabled_cmdline(fdt)) {
 		kaslr_status = KASLR_DISABLED_CMDLINE;
 		return 0;
 	}
-- 
2.25.1