diff options
| author | Ard Biesheuvel <ardb@kernel.org> | 2023-11-29 12:16:15 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2023-12-12 11:13:53 +0000 |
| commit | ea48626f8f0efc697555d17bb5853df92461e280 (patch) | |
| tree | 6ff6aa527962921780555a352563fac56bec15e5 /arch/arm64/kernel | |
| parent | 060260a6be47ae163b0c71a6d0902d065b68f3d2 (diff) | |
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: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20231129111555.3594833-62-ardb@google.com
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel')
| -rw-r--r-- | arch/arm64/kernel/idreg-override.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c index cf1df5f6fbc1..9646f94094ed 100644 --- a/arch/arm64/kernel/idreg-override.c +++ b/arch/arm64/kernel/idreg-override.c @@ -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) |