From: Dmitry Vyukov <dvyukov(a)google.com>
POSIX timers using the CLOCK_PROCESS_CPUTIME_ID clock prefer the main
thread of a thread group for signal delivery. However, this has a
significant downside: it requires waking up a potentially idle thread.
Instead, prefer to deliver signals to the current thread (in the same
thread group) if SIGEV_THREAD_ID is not set by the user. This does not
change guaranteed semantics, since POSIX process CPU time timers have
never guaranteed that signal delivery is to a specific thread (without
SIGEV_THREAD_ID set).
The effect is that we no longer wake up potentially idle threads, and
the kernel is no longer biased towards delivering the timer signal to
any particular thread (which better distributes the timer signals esp.
when multiple timers fire concurrently).
Signed-off-by: Dmitry Vyukov <dvyukov(a)google.com>
Suggested-by: Oleg Nesterov <oleg(a)redhat.com>
Reviewed-by: Oleg Nesterov <oleg(a)redhat.com>
Signed-off-by: Marco Elver <elver(a)google.com>
---
v6:
- Split test from this patch.
- Update wording on what this patch aims to improve.
v5:
- Rebased onto v6.2.
v4:
- Restructured checks in send_sigqueue() as suggested.
v3:
- Switched to the completely different implementation (much simpler)
based on the Oleg's idea.
RFC v2:
- Added additional Cc as Thomas asked.
---
kernel/signal.c | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/kernel/signal.c b/kernel/signal.c
index 8cb28f1df294..605445fa27d4 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1003,8 +1003,7 @@ static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
/*
* Now find a thread we can wake up to take the signal off the queue.
*
- * If the main thread wants the signal, it gets first crack.
- * Probably the least surprising to the average bear.
+ * Try the suggested task first (may or may not be the main thread).
*/
if (wants_signal(sig, p))
t = p;
@@ -1970,8 +1969,23 @@ int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
ret = -1;
rcu_read_lock();
+ /*
+ * This function is used by POSIX timers to deliver a timer signal.
+ * Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID
+ * set), the signal must be delivered to the specific thread (queues
+ * into t->pending).
+ *
+ * Where type is not PIDTYPE_PID, signals must just be delivered to the
+ * current process. In this case, prefer to deliver to current if it is
+ * in the same thread group as the target, as it avoids unnecessarily
+ * waking up a potentially idle task.
+ */
t = pid_task(pid, type);
- if (!t || !likely(lock_task_sighand(t, &flags)))
+ if (!t)
+ goto ret;
+ if (type != PIDTYPE_PID && same_thread_group(t, current))
+ t = current;
+ if (!likely(lock_task_sighand(t, &flags)))
goto ret;
ret = 1; /* the signal is ignored */
@@ -1993,6 +2007,11 @@ int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
q->info.si_overrun = 0;
signalfd_notify(t, sig);
+ /*
+ * If the type is not PIDTYPE_PID, we just use shared_pending, which
+ * won't guarantee that the specified task will receive the signal, but
+ * is sufficient if t==current in the common case.
+ */
pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
list_add_tail(&q->list, &pending->list);
sigaddset(&pending->signal, sig);
--
2.40.0.rc1.284.g88254d51c5-goog
Currently, the sud_test expects the emulated syscall to return the
emulated syscall number. This assumption only works on architectures
were the syscall calling convention use the same register for syscall
number/syscall return value. This is not the case for RISC-V and thus
the return value must be also emulated using the provided ucontext.
Signed-off-by: Clément Léger <cleger(a)rivosinc.com>
Reviewed-by: Palmer Dabbelt <palmer(a)rivosinc.com>
Acked-by: Palmer Dabbelt <palmer(a)rivosinc.com>
---
Changes in V2:
- Changes comment to be more explicit
- Use A7 syscall arg rather than hardcoding MAGIC_SYSCALL_1
---
.../selftests/syscall_user_dispatch/sud_test.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/tools/testing/selftests/syscall_user_dispatch/sud_test.c b/tools/testing/selftests/syscall_user_dispatch/sud_test.c
index b5d592d4099e..d975a6767329 100644
--- a/tools/testing/selftests/syscall_user_dispatch/sud_test.c
+++ b/tools/testing/selftests/syscall_user_dispatch/sud_test.c
@@ -158,6 +158,20 @@ static void handle_sigsys(int sig, siginfo_t *info, void *ucontext)
/* In preparation for sigreturn. */
SYSCALL_DISPATCH_OFF(glob_sel);
+
+ /*
+ * The tests for argument handling assume that `syscall(x) == x`. This
+ * is a NOP on x86 because the syscall number is passed in %rax, which
+ * happens to also be the function ABI return register. Other
+ * architectures may need to swizzle the arguments around.
+ */
+#if defined(__riscv)
+/* REG_A7 is not defined in libc headers */
+# define REG_A7 (REG_A0 + 7)
+
+ ((ucontext_t *)ucontext)->uc_mcontext.__gregs[REG_A0] =
+ ((ucontext_t *)ucontext)->uc_mcontext.__gregs[REG_A7];
+#endif
}
TEST(dispatch_and_return)
--
2.43.0
PASID (Process Address Space ID) is a PCIe extension to tag the DMA
transactions out of a physical device, and most modern IOMMU hardware
have supported PASID granular address translation. So a PASID-capable
device can be attached to multiple hwpts (a.k.a. domains), each attachment
is tagged with a pasid.
This series first adds a missing iommu API to replace domain for a pasid,
then adds iommufd APIs for device drivers to attach/replace/detach pasid
to/from hwpt per userspace's request, and adds selftest to validate the
iommufd APIs.
pasid attach/replace is mandatory on Intel VT-d given the PASID table
locates in the physical address space hence must be managed by the kernel,
both for supporting vSVA and coming SIOV. But it's optional on ARM/AMD
which allow configuring the PASID/CD table either in host physical address
space or nested on top of an GPA address space. This series only add VT-d
support as the minimal requirement.
Complete code can be found in below link:
https://github.com/yiliu1765/iommufd/tree/iommufd_pasid
Change log:
v1:
- Implemnet iommu_replace_device_pasid() to fall back to the original domain
if this replacement failed (Kevin)
- Add check in do_attach() to check corressponding attach_fn per the pasid value.
rfc: https://lore.kernel.org/linux-iommu/20230926092651.17041-1-yi.l.liu@intel.c…
Regards,
Yi Liu
Kevin Tian (1):
iommufd: Support attach/replace hwpt per pasid
Lu Baolu (2):
iommu: Introduce a replace API for device pasid
iommu/vt-d: Add set_dev_pasid callback for nested domain
Yi Liu (5):
iommufd: replace attach_fn with a structure
iommufd/selftest: Add set_dev_pasid and remove_dev_pasid in mock iommu
iommufd/selftest: Add a helper to get test device
iommufd/selftest: Add test ops to test pasid attach/detach
iommufd/selftest: Add coverage for iommufd pasid attach/detach
drivers/iommu/intel/nested.c | 47 +++++
drivers/iommu/iommu-priv.h | 2 +
drivers/iommu/iommu.c | 82 ++++++--
drivers/iommu/iommufd/Makefile | 1 +
drivers/iommu/iommufd/device.c | 50 +++--
drivers/iommu/iommufd/iommufd_private.h | 23 +++
drivers/iommu/iommufd/iommufd_test.h | 24 +++
drivers/iommu/iommufd/pasid.c | 138 ++++++++++++++
drivers/iommu/iommufd/selftest.c | 176 ++++++++++++++++--
include/linux/iommufd.h | 6 +
tools/testing/selftests/iommu/iommufd.c | 172 +++++++++++++++++
.../selftests/iommu/iommufd_fail_nth.c | 28 ++-
tools/testing/selftests/iommu/iommufd_utils.h | 78 ++++++++
13 files changed, 785 insertions(+), 42 deletions(-)
create mode 100644 drivers/iommu/iommufd/pasid.c
--
2.34.1
On riscv, mmap currently returns an address from the largest address
space that can fit entirely inside of the hint address. This makes it
such that the hint address is almost never returned. This patch raises
the mappable area up to and including the hint address. This allows mmap
to often return the hint address, which allows a performance improvement
over searching for a valid address as well as making the behavior more
similar to other architectures.
Note that a previous patch introduced stronger semantics compared to
other architectures for riscv mmap. On riscv, mmap will not use bits in
the upper bits of the virtual address depending on the hint address. On
other architectures, a random address is returned in the address space
requested. On all architectures the hint address will be returned if it
is available. This allows riscv applications to configure how many bits
in the virtual address should be left empty. This has the two benefits
of being able to request address spaces that are smaller than the
default and doesn't require the application to know the page table
layout of riscv.
Signed-off-by: Charlie Jenkins <charlie(a)rivosinc.com>
---
Changes in v2:
- Add back forgotten "mmap_end = STACK_TOP_MAX"
- Link to v1: https://lore.kernel.org/r/20240129-use_mmap_hint_address-v1-0-4c74da813ba1@…
---
Charlie Jenkins (3):
riscv: mm: Use hint address in mmap if available
selftests: riscv: Generalize mm selftests
docs: riscv: Define behavior of mmap
Documentation/arch/riscv/vm-layout.rst | 16 ++--
arch/riscv/include/asm/processor.h | 22 +++---
tools/testing/selftests/riscv/mm/mmap_bottomup.c | 20 +----
tools/testing/selftests/riscv/mm/mmap_default.c | 20 +----
tools/testing/selftests/riscv/mm/mmap_test.h | 93 +++++++++++++-----------
5 files changed, 67 insertions(+), 104 deletions(-)
---
base-commit: 556e2d17cae620d549c5474b1ece053430cd50bc
change-id: 20240119-use_mmap_hint_address-f9f4b1b6f5f1
--
- Charlie
In this series, I'm trying to add 3 missing tests to vm_runtests.sh
which is used to run all the tests in mm suite. These tests weren't
running by CIs. While enabling them and through review feedback, I've
fixed some problems in tests as well. I've found more flakiness in more
tests which I'll be fixing with future patches.
hugetlb-read-hwpoison test is being added where it can only run with
newly added "-d" (destructive) flag only. Not sure why it is failing
again. So once it become stable, we can think of moving it to default
set of tests if it doesn't have any side-effect to them.
Cc: Ryan Roberts <ryan.roberts(a)arm.com>
Cc: Andrew Morton <akpm(a)linux-foundation.org>
---
Changes in v3:
- Add cover letter
- Fix flakiness in tests found during enablement
- Move additional tests down in the file
- Add "-d" option which poisons the pages and aren't being useable after
the test
v2: https://lore.kernel.org/all/20240123073615.920324-1-usama.anjum@collabora.c…
Muhammad Usama Anjum (5):
selftests/mm: hugetlb_reparenting_test: do not unmount
selftests/mm: run_vmtests: remove sudo and conform to tap
selftests/mm: save and restore nr_hugepages value
selftests/mm: protection_keys: save/restore nr_hugepages settings
selftests/mm: run_vmtests.sh: add missing tests
tools/testing/selftests/mm/Makefile | 5 +++
.../selftests/mm/charge_reserved_hugetlb.sh | 4 +++
.../selftests/mm/hugetlb_reparenting_test.sh | 9 +++--
tools/testing/selftests/mm/on-fault-limit.c | 36 +++++++++----------
tools/testing/selftests/mm/protection_keys.c | 34 ++++++++++++++++++
tools/testing/selftests/mm/run_vmtests.sh | 10 +++++-
6 files changed, 76 insertions(+), 22 deletions(-)
--
2.42.0
v3: Rebase on the next branch of linux-kselftest.git,
modify the patch title and update the commit message
v2: Rebase on 6.5-rc1 and update the commit message
Tiezhu Yang (2):
selftests/vDSO: Fix building errors on LoongArch
selftests/vDSO: Fix runtime errors on LoongArch
tools/testing/selftests/vDSO/vdso_config.h | 6 ++++-
.../testing/selftests/vDSO/vdso_test_getcpu.c | 16 +++++-------
.../selftests/vDSO/vdso_test_gettimeofday.c | 26 +++++--------------
3 files changed, 18 insertions(+), 30 deletions(-)
--
2.42.0