hollalinux
/
linux-sg2042
mirror of https://github.com/sophgo/linux-riscv.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

x86/boot: Allow a "silent" kaslr random byte fetch 

Under earlyprintk, each RNG call produces a debug report line. To support
the future FGKASLR feature, which will fetch random bytes during function
shuffling, this is not useful information (each line is identical and
tells us nothing new), needlessly spamming the console. Instead, allow
for a NULL "purpose" to suppress the debug reporting.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20211013175742.1197608-3-keescook@chromium.org
This commit is contained in:
Kees Cook 2021-10-13 10:57:40 -07:00 committed by Peter Zijlstra
parent a54c401ae6
commit 0d054d4e82
1 changed files with 12 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
arch/x86/lib/kaslr.c
View File

@ -56,11 +56,14 @@ unsigned long kaslr_get_random_long(const char *purpose)
unsigned long raw, random = get_boot_seed();
bool use_i8254 = true;
debug_putstr(purpose);
debug_putstr(" KASLR using");
if (purpose) {
debug_putstr(purpose);
debug_putstr(" KASLR using");
}
if (has_cpuflag(X86_FEATURE_RDRAND)) {
debug_putstr(" RDRAND");
if (purpose)
debug_putstr(" RDRAND");
if (rdrand_long(&raw)) {
random ^= raw;
use_i8254 = false;
@ -68,7 +71,8 @@ unsigned long kaslr_get_random_long(const char *purpose)
}
if (has_cpuflag(X86_FEATURE_TSC)) {
debug_putstr(" RDTSC");
if (purpose)
debug_putstr(" RDTSC");
raw = rdtsc();
random ^= raw;
@ -76,7 +80,8 @@ unsigned long kaslr_get_random_long(const char *purpose)
}
if (use_i8254) {
debug_putstr(" i8254");
if (purpose)
debug_putstr(" i8254");
random ^= i8254();
}
@ -86,7 +91,8 @@ unsigned long kaslr_get_random_long(const char *purpose)
: "a" (random), "rm" (mix_const));
random += raw;
debug_putstr("...\n");
if (purpose)
debug_putstr("...\n");
return random;
}