Messages in this thread Patch in this message | | | From | Ard Biesheuvel <> | Subject | [PATCH v3 22/60] arm64: idreg-override: Avoid kstrtou64() to parse a single hex digit | Date | Tue, 7 Mar 2023 15:04:44 +0100 |
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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: Ard Biesheuvel <ardb@kernel.org> --- arch/arm64/kernel/idreg-override.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c index 58c02fe20e1050b4..758f0e86e2bd2a34 100644 --- a/arch/arm64/kernel/idreg-override.c +++ b/arch/arm64/kernel/idreg-override.c @@ -195,6 +195,20 @@ static const struct { { "nokaslr", "arm64_sw.nokaslr=1" }, }; +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) { @@ -208,7 +222,7 @@ 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) -- 2.39.2
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