kernel.git/arch/riscv/kernel/vdso.c, branch linux-5.18.y

riscv/vdso: Add support for time namespaces

2021-10-04T21:16:43Z

Implement generic vdso time namespace support which also enables time namespaces for riscv. This is quite similar to what arm64 does. selftest/timens test result: 1..10 ok 1 Passed for CLOCK_BOOTTIME (syscall) ok 2 Passed for CLOCK_BOOTTIME (vdso) ok 3 # SKIP CLOCK_BOOTTIME_ALARM isn't supported ok 4 # SKIP CLOCK_BOOTTIME_ALARM isn't supported ok 5 Passed for CLOCK_MONOTONIC (syscall) ok 6 Passed for CLOCK_MONOTONIC (vdso) ok 7 Passed for CLOCK_MONOTONIC_COARSE (syscall) ok 8 Passed for CLOCK_MONOTONIC_COARSE (vdso) ok 9 Passed for CLOCK_MONOTONIC_RAW (syscall) ok 10 Passed for CLOCK_MONOTONIC_RAW (vdso) # Totals: pass:8 fail:0 xfail:0 xpass:0 skip:2 error:0 Signed-off-by: Tong Tiangen Signed-off-by: Palmer Dabbelt

riscv/vdso: make arch_setup_additional_pages wait for mmap_sem for write killable

2021-10-02T20:42:26Z

riscv architectures relying on mmap_sem for write in their arch_setup_additional_pages. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. Signed-off-by: Tong Tiangen Reviewed-by: Kefeng Wang Fixes: 76d2a0493a17 ("RISC-V: Init and Halt Code") Signed-off-by: Palmer Dabbelt

riscv/vdso: Move vdso data page up front

2021-10-02T20:42:25Z

As commit 601255ae3c98 ("arm64: vdso: move data page before code pages"), the same issue exists on riscv, testcase is shown below, make sure that vdso.so is bigger than page size, struct timespec tp; clock_gettime(5, &tp); printf("tv_sec: %ld, tv_nsec: %ld\n", tp.tv_sec, tp.tv_nsec); without this patch, test result : tv_sec: 0, tv_nsec: 0 with this patch, test result : tv_sec: 1629271537, tv_nsec: 748000000 Move the vdso data page in front of the VDSO area to fix the issue. Fixes: ad5d1122b82fb ("riscv: use vDSO common flow to reduce the latency of the time-related functions") Signed-off-by: Tong Tiangen Reviewed-by: Kefeng Wang Signed-off-by: Palmer Dabbelt

riscv/vdso: Refactor asm/vdso.h

2021-10-02T20:42:23Z

The asm/vdso.h will be included in vdso.lds.S in the next patch, the following cleanup is needed to avoid syntax error: 1.the declaration of sys_riscv_flush_icache() is moved into asm/syscall.h. 2.the definition of struct vdso_data is moved into kernel/vdso.c. 2.the definition of VDSO_SYMBOL is placed under "#ifndef __ASSEMBLY__". Also remove the redundant linux/types.h include. Signed-off-by: Tong Tiangen Reviewed-by: Kefeng Wang Signed-off-by: Palmer Dabbelt

riscv: Mark some global variables __ro_after_init

2021-04-26T15:25:08Z

All of these are never modified after init, so they can be __ro_after_init. Signed-off-by: Jisheng Zhang Signed-off-by: Palmer Dabbelt

riscv: Fixup CONFIG_GENERIC_TIME_VSYSCALL

2021-01-13T04:34:44Z

The patch fix commit: ad5d112 ("riscv: use vDSO common flow to reduce the latency of the time-related functions"). The GENERIC_TIME_VSYSCALL should be CONFIG_GENERIC_TIME_VSYSCALL or vgettimeofday won't work. Signed-off-by: Guo Ren Reviewed-by: Pekka Enberg Fixes: ad5d1122b82f ("riscv: use vDSO common flow to reduce the latency of the time-related functions") Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt

Merge tag 'riscv-for-linus-5.8-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2020-06-11T19:55:20Z

Pull more RISC-V updates from Palmer Dabbelt: - Kconfig select statements are now sorted alphanumerically - first-level interrupts are now handled via a full irqchip driver - CPU hotplug is fixed - vDSO calls now use the common vDSO infrastructure * tag 'riscv-for-linus-5.8-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: riscv: set the permission of vdso_data to read-only riscv: use vDSO common flow to reduce the latency of the time-related functions riscv: fix build warning of missing prototypes RISC-V: Don't mark init section as non-executable RISC-V: Force select RISCV_INTC for CONFIG_RISCV RISC-V: Remove do_IRQ() function clocksource/drivers/timer-riscv: Use per-CPU timer interrupt irqchip: RISC-V per-HART local interrupt controller driver RISC-V: Rename and move plic_find_hart_id() to arch directory RISC-V: self-contained IPI handling routine RISC-V: Sort select statements alphanumerically

riscv: set the permission of vdso_data to read-only

2020-06-11T02:47:35Z

The original vdso_data page is empty, so the permission of the vdso_data page can be the same with the vdso text page. After introducing the vDSO common flow, the vdso_data is not empty and the permission should be changed to read-only. Signed-off-by: Vincent Chen Signed-off-by: Palmer Dabbelt

riscv: use vDSO common flow to reduce the latency of the time-related functions

2020-06-11T02:47:16Z

Even if RISC-V has supported the vDSO feature, the latency of the functions for obtaining the system time is still expensive. It is because these functions still trigger a corresponding system call in the process, which slows down the response time. If we want to remove the system call to reduce the latency, the kernel should have the ability to output the system clock information to userspace. This patch introduces the vDSO common flow to enable the kernel to achieve the above feature and uses "rdtime" instruction to obtain the current time in the user space. Under this condition, the latency cost by the ecall from U-mode to S-mode can be eliminated. After applying this patch, the latency of gettimeofday() measured on the HiFive unleashed board can be reduced by %61. Signed-off-by: Vincent Chen Reviewed-by: Atish Patra Signed-off-by: Palmer Dabbelt

mmap locking API: use coccinelle to convert mmap_sem rwsem call sites

2020-06-09T16:39:14Z

This change converts the existing mmap_sem rwsem calls to use the new mmap locking API instead. The change is generated using coccinelle with the following rule: // spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir . @@ expression mm; @@ ( -init_rwsem +mmap_init_lock | -down_write +mmap_write_lock | -down_write_killable +mmap_write_lock_killable | -down_write_trylock +mmap_write_trylock | -up_write +mmap_write_unlock | -downgrade_write +mmap_write_downgrade | -down_read +mmap_read_lock | -down_read_killable +mmap_read_lock_killable | -down_read_trylock +mmap_read_trylock | -up_read +mmap_read_unlock ) -(&mm->mmap_sem) +(mm) Signed-off-by: Michel Lespinasse Signed-off-by: Andrew Morton Reviewed-by: Daniel Jordan Reviewed-by: Laurent Dufour Reviewed-by: Vlastimil Babka Cc: Davidlohr Bueso Cc: David Rientjes Cc: Hugh Dickins Cc: Jason Gunthorpe Cc: Jerome Glisse Cc: John Hubbard Cc: Liam Howlett Cc: Matthew Wilcox Cc: Peter Zijlstra Cc: Ying Han Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com Signed-off-by: Linus Torvalds