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Commit 9005c683 authored by KarimAllah Ahmed's avatar KarimAllah Ahmed Committed by Thomas Gleixner
Browse files

x86/spectre: Simplify spectre_v2 command line parsing 



[dwmw2: Use ARRAY_SIZE]

Signed-off-by: default avatarKarimAllah Ahmed <karahmed@amazon.de>
Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: peterz@infradead.org
Cc: bp@alien8.de
Link: https://lkml.kernel.org/r/1517484441-1420-3-git-send-email-dwmw@amazon.co.uk
parent 66f79309

arch/x86/kernel/cpu/bugs.c

+56 −30
Original line number Diff line number Diff line
@@ -119,13 +119,13 @@ static inline const char *spectre_v2_module_string(void) { return ""; } 
static void __init spec2_print_if_insecure(const char *reason)

{

	if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2))

		pr_info("%s\n", reason);

		pr_info("%s selected on command line.\n", reason);

}



static void __init spec2_print_if_secure(const char *reason)

{

	if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))

		pr_info("%s\n", reason);

		pr_info("%s selected on command line.\n", reason);

}



static inline bool retp_compiler(void)
@@ -140,42 +140,68 @@ static inline bool match_option(const char *arg, int arglen, const char *opt) 
	return len == arglen && !strncmp(arg, opt, len);

}



static const struct {

	const char *option;

	enum spectre_v2_mitigation_cmd cmd;

	bool secure;

} mitigation_options[] = {

	{ "off",               SPECTRE_V2_CMD_NONE,              false },

	{ "on",                SPECTRE_V2_CMD_FORCE,             true },

	{ "retpoline",         SPECTRE_V2_CMD_RETPOLINE,         false },

	{ "retpoline,amd",     SPECTRE_V2_CMD_RETPOLINE_AMD,     false },

	{ "retpoline,generic", SPECTRE_V2_CMD_RETPOLINE_GENERIC, false },

	{ "auto",              SPECTRE_V2_CMD_AUTO,              false },

};



static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)

{

	char arg[20];

	int ret;

	int ret, i;

	enum spectre_v2_mitigation_cmd cmd = SPECTRE_V2_CMD_AUTO;



	if (cmdline_find_option_bool(boot_command_line, "nospectre_v2"))

		return SPECTRE_V2_CMD_NONE;

	else {

		ret = cmdline_find_option(boot_command_line, "spectre_v2", arg,

					  sizeof(arg));

	if (ret > 0)  {

		if (match_option(arg, ret, "off")) {

			goto disable;

		} else if (match_option(arg, ret, "on")) {

			spec2_print_if_secure("force enabled on command line.");

			return SPECTRE_V2_CMD_FORCE;

		} else if (match_option(arg, ret, "retpoline")) {

			spec2_print_if_insecure("retpoline selected on command line.");

			return SPECTRE_V2_CMD_RETPOLINE;

		} else if (match_option(arg, ret, "retpoline,amd")) {

			if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD) {

				pr_err("retpoline,amd selected but CPU is not AMD. Switching to AUTO select\n");

		if (ret < 0)

			return SPECTRE_V2_CMD_AUTO;



		for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) {

			if (!match_option(arg, ret, mitigation_options[i].option))

				continue;

			cmd = mitigation_options[i].cmd;

			break;

		}

			spec2_print_if_insecure("AMD retpoline selected on command line.");

			return SPECTRE_V2_CMD_RETPOLINE_AMD;

		} else if (match_option(arg, ret, "retpoline,generic")) {

			spec2_print_if_insecure("generic retpoline selected on command line.");

			return SPECTRE_V2_CMD_RETPOLINE_GENERIC;

		} else if (match_option(arg, ret, "auto")) {



		if (i >= ARRAY_SIZE(mitigation_options)) {

			pr_err("unknown option (%s). Switching to AUTO select\n",

			       mitigation_options[i].option);

			return SPECTRE_V2_CMD_AUTO;

		}

	}



	if (!cmdline_find_option_bool(boot_command_line, "nospectre_v2"))

	if ((cmd == SPECTRE_V2_CMD_RETPOLINE ||

	     cmd == SPECTRE_V2_CMD_RETPOLINE_AMD ||

	     cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC) &&

	    !IS_ENABLED(CONFIG_RETPOLINE)) {

		pr_err("%s selected but not compiled in. Switching to AUTO select\n",

		       mitigation_options[i].option);

		return SPECTRE_V2_CMD_AUTO;

disable:

	spec2_print_if_insecure("disabled on command line.");

	return SPECTRE_V2_CMD_NONE;

	}



	if (cmd == SPECTRE_V2_CMD_RETPOLINE_AMD &&

	    boot_cpu_data.x86_vendor != X86_VENDOR_AMD) {

		pr_err("retpoline,amd selected but CPU is not AMD. Switching to AUTO select\n");

		return SPECTRE_V2_CMD_AUTO;

	}



	if (mitigation_options[i].secure)

		spec2_print_if_secure(mitigation_options[i].option);

	else

		spec2_print_if_insecure(mitigation_options[i].option);



	return cmd;

}



/* Check for Skylake-like CPUs (for RSB handling) */