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arm64: kaslr: Use feature override instead of parsing the cmdline again 

The early kaslr code open codes the detection of 'nokaslr' on the kernel
command line, and this is no longer necessary now that the feature
detection code, which also looks for the same string, executes before
this code.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-56-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ard Biesheuvel 2024-02-14 13:28:57 +01:00 committed by Catalin Marinas
parent 35876f35f4
commit af73b9a2dd
3 changed files with 7 additions and 55 deletions
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5
arch/arm64/include/asm/cpufeature.h
View File

@ -954,6 +954,11 @@ static inline bool arm64_test_sw_feature_override(int feat)
&arm64_sw_feature_override);
}
static inline bool kaslr_disabled_cmdline(void)
{
return arm64_test_sw_feature_override(ARM64_SW_FEATURE_OVERRIDE_NOKASLR);
}
u32 get_kvm_ipa_limit(void);
void dump_cpu_features(void);

4
arch/arm64/kernel/kaslr.c
View File

@ -16,9 +16,7 @@ bool __ro_after_init __kaslr_is_enabled = false;
void __init kaslr_init(void)
{
if (cpuid_feature_extract_unsigned_field(arm64_sw_feature_override.val &
arm64_sw_feature_override.mask,
ARM64_SW_FEATURE_OVERRIDE_NOKASLR)) {
if (kaslr_disabled_cmdline()) {
pr_info("KASLR disabled on command line\n");
return;
}

53
arch/arm64/kernel/pi/kaslr_early.c
View File

@ -16,57 +16,6 @@
#include <asm/memory.h>
#include <asm/pgtable.h>
/* taken from lib/string.c */
static char *__init __strstr(const char *s1, const char *s2)
{
size_t l1, l2;
l2 = strlen(s2);
if (!l2)
return (char *)s1;
l1 = strlen(s1);
while (l1 >= l2) {
l1--;
if (!memcmp(s1, s2, l2))
return (char *)s1;
s1++;
}
return NULL;
}
static bool __init cmdline_contains_nokaslr(const u8 *cmdline)
{
const u8 *str;
str = __strstr(cmdline, "nokaslr");
return str == cmdline || (str > cmdline && *(str - 1) == ' ');
}
static bool __init is_kaslr_disabled_cmdline(void *fdt)
{
if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) {
int node;
const u8 *prop;
node = fdt_path_offset(fdt, "/chosen");
if (node < 0)
goto out;
prop = fdt_getprop(fdt, node, "bootargs", NULL);
if (!prop)
goto out;
if (cmdline_contains_nokaslr(prop))
return true;
if (IS_ENABLED(CONFIG_CMDLINE_EXTEND))
goto out;
return false;
}
out:
return cmdline_contains_nokaslr(CONFIG_CMDLINE);
}
static u64 __init get_kaslr_seed(void *fdt)
{
static char const chosen_str[] __initconst = "chosen";
@ -92,7 +41,7 @@ asmlinkage u64 __init kaslr_early_init(void *fdt)
{
u64 seed, range;
if (is_kaslr_disabled_cmdline(fdt))
if (kaslr_disabled_cmdline())
return 0;
seed = get_kaslr_seed(fdt);