Skip to content

[libc] implement clock_gettime using vDSO #108458

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Sep 13, 2024
Merged

[libc] implement clock_gettime using vDSO #108458

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
8d41997
[libc] implement clock_gettime using vDSO
SchrodingerZhu Sep 12, 2024
043dae5
fix
SchrodingerZhu Sep 13, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions libc/src/__support/time/linux/CMakeLists.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ add_header_library(
libc.src.__support.common
libc.src.__support.error_or
libc.src.__support.OSUtil.osutil
libc.src.__support.OSUtil.vdso
)

add_header_library(
Expand Down
35 changes: 28 additions & 7 deletions libc/src/__support/time/linux/clock_gettime.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -11,26 +11,47 @@

#include "hdr/types/clockid_t.h"
#include "hdr/types/struct_timespec.h"
#include "src/__support/OSUtil/linux/vdso.h"
#include "src/__support/OSUtil/syscall.h"
#include "src/__support/common.h"
#include "src/__support/error_or.h"
#include "src/__support/macros/config.h"
#include <sys/syscall.h>

#if defined(SYS_clock_gettime64)
#include <linux/time_types.h>
#endif

namespace LIBC_NAMESPACE_DECL {
namespace internal {
LIBC_INLINE ErrorOr<int> clock_gettime(clockid_t clockid, timespec *ts) {
#if SYS_clock_gettime
int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_clock_gettime,
static_cast<long>(clockid),
reinterpret_cast<long>(ts));
using namespace vdso;
int ret;
#if defined(SYS_clock_gettime)
TypedSymbol<VDSOSym::ClockGetTime> clock_gettime;
if (LIBC_LIKELY(clock_gettime != nullptr))
ret = clock_gettime(clockid, ts);
else
ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_clock_gettime,
static_cast<long>(clockid),
reinterpret_cast<long>(ts));
#elif defined(SYS_clock_gettime64)
static_assert(
sizeof(time_t) == sizeof(int64_t),
"SYS_clock_gettime64 requires struct timespec with 64-bit members.");
int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_clock_gettime64,
static_cast<long>(clockid),
reinterpret_cast<long>(ts));

TypedSymbol<VDSOSym::ClockGetTime64> clock_gettime64;
__kernel_timespec ts64{};
if (LIBC_LIKELY(clock_gettime64 != nullptr))
ret = clock_gettime64(clockid, &ts64);
else
ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_clock_gettime64,
static_cast<long>(clockid),
reinterpret_cast<long>(&ts64));
if (ret == 0) {
ts->tv_sec = static_cast<decltype(ts->tv_sec)>(ts64.tv_sec);
ts->tv_nsec = static_cast<decltype(ts->tv_nsec)>(ts64.tv_nsec);
}
#else
#error "SYS_clock_gettime and SYS_clock_gettime64 syscalls not available."
#endif
Expand Down
Loading