Commit ea48626f authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Will Deacon
Browse files

arm64: idreg-override: Avoid kstrtou64() to parse a single hex digit 



All ID register value overrides are =0 with the exception of the nokaslr
pseudo feature which uses =1. In order to remove the dependency on
kstrtou64(), which is part of the core kernel and no longer usable once
we move idreg-override into the early mini C runtime, let's just parse a
single hex digit (with optional leading 0x) and set the output value
accordingly.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20231129111555.3594833-62-ardb@google.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 060260a6

arch/arm64/kernel/idreg-override.c

+15 −1
Original line number Diff line number Diff line
@@ -206,6 +206,20 @@ static int __init parse_nokaslr(char *unused) 
}

early_param("nokaslr", parse_nokaslr);



static int __init parse_hexdigit(const char *p, u64 *v)

{

	// skip "0x" if it comes next

	if (p[0] == '0' && tolower(p[1]) == 'x')

		p += 2;



	// check whether the RHS is a single hex digit

	if (!isxdigit(p[0]) || (p[1] && !isspace(p[1])))

		return -EINVAL;



	*v = tolower(*p) - (isdigit(*p) ? '0' : 'a' - 10);

	return 0;

}



static int __init find_field(const char *cmdline, char *opt, int len,

			     const struct ftr_set_desc *reg, int f, u64 *v)

{
@@ -219,7 +233,7 @@ static int __init find_field(const char *cmdline, char *opt, int len, 
	if (memcmp(cmdline, opt, len))

		return -1;



	return kstrtou64(cmdline + len, 0, v);

	return parse_hexdigit(cmdline + len, v);

}



static void __init match_options(const char *cmdline)