diff options
| author | Yidi Lin <yidilin@chromium.org> | 2023-11-02 14:17:02 +0800 |
|---|---|---|
| committer | Julius Werner <jwerner@chromium.org> | 2023-11-07 19:25:23 +0000 |
| commit | eabdd0252a2c3f8fb03b83781019243d47737e80 (patch) | |
| tree | 2b3665eb5e1cebfa09aaa7151d02378d1797a9ad /payloads/libpayload/drivers/timer | |
| parent | e91785dfd8fd29a2f39a1f0ceb143015536706fb (diff) | |
libpayload/libc/time: Fix possible overflow in multiplication
The value from raw_read_cntfrq_el0() could be large enough to cause
overflow when multiplied by USECS_PER_SEC. To prevent this, both
USECS_PER_SEC and hz can be reduced by dividing them by their GCD.
This patch also modifies the return type of `timer_hz()` from
`uint64_t` to `uint32_t`, assuming that in practice the timestamp
counter should never be that fast.
BUG=b:307790895
TEST=boot to kernel and check the timestamps from `cbmem`
Change-Id: Ia55532490651fcf47128b83a8554751f050bcc89
Signed-off-by: Yidi Lin <yidilin@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78888
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Diffstat (limited to 'payloads/libpayload/drivers/timer')
| -rw-r--r-- | payloads/libpayload/drivers/timer/arm64_arch_timer.c | 2 | ||||
| -rw-r--r-- | payloads/libpayload/drivers/timer/generic.c | 2 | ||||
| -rw-r--r-- | payloads/libpayload/drivers/timer/rdtsc.c | 6 |
3 files changed, 6 insertions, 4 deletions
diff --git a/payloads/libpayload/drivers/timer/arm64_arch_timer.c b/payloads/libpayload/drivers/timer/arm64_arch_timer.c index 087d9e7565..b4d2b865ae 100644 --- a/payloads/libpayload/drivers/timer/arm64_arch_timer.c +++ b/payloads/libpayload/drivers/timer/arm64_arch_timer.c @@ -32,7 +32,7 @@ #include <arch/lib_helpers.h> #include <libpayload.h> -uint64_t timer_hz(void) +uint32_t timer_hz(void) { return raw_read_cntfrq_el0(); } diff --git a/payloads/libpayload/drivers/timer/generic.c b/payloads/libpayload/drivers/timer/generic.c index ef9eda54ad..bd5674be8c 100644 --- a/payloads/libpayload/drivers/timer/generic.c +++ b/payloads/libpayload/drivers/timer/generic.c @@ -33,7 +33,7 @@ #include <assert.h> #include <libpayload.h> -uint64_t timer_hz(void) +uint32_t timer_hz(void) { /* libc/time.c currently requires all timers to be at least 1MHz. */ assert(CONFIG_LP_TIMER_GENERIC_HZ >= 1000000); diff --git a/payloads/libpayload/drivers/timer/rdtsc.c b/payloads/libpayload/drivers/timer/rdtsc.c index cfd56b064a..952bc0bb13 100644 --- a/payloads/libpayload/drivers/timer/rdtsc.c +++ b/payloads/libpayload/drivers/timer/rdtsc.c @@ -33,10 +33,12 @@ #include <libpayload.h> #include <arch/rdtsc.h> +#include <assert.h> -uint64_t timer_hz(void) +uint32_t timer_hz(void) { - return (uint64_t)lib_sysinfo.cpu_khz * 1000; + assert(UINT32_MAX / 1000 >= lib_sysinfo.cpu_khz); + return lib_sysinfo.cpu_khz * 1000; } uint64_t timer_raw_value(void) |