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linux/debian/patches/patchset-pf/pksm/0001-mm-expose-per-process-KSM-control-via-syscalls.patch

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From 4eb6615c1498cb8bff76c31e9596b585410f507d Mon Sep 17 00:00:00 2001
From: Oleksandr Natalenko <oleksandr@natalenko.name>
Date: Mon, 30 Sep 2024 08:58:38 +0200
Subject: mm: expose per-process KSM control via syscalls
d7597f59d1d3 added a new API to enable per-process KSM control. It
however uses prctl, which doesn't allow controlling KSM from outside of
the current process.
Hence, expose this API via 3 syscalls: process_ksm_enable,
process_ksm_disable and process_ksm_status. Given sufficient privileges,
auto-KSM can be enable by another process.
Since these syscalls are not in the upstream kernel, also expose their
numbers under /sys/kernel/process_ksm so that userspace tooling like
uksmd knows how to use them.
Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name>
---
arch/alpha/kernel/syscalls/syscall.tbl | 3 +
arch/arm/tools/syscall.tbl | 3 +
arch/m68k/kernel/syscalls/syscall.tbl | 3 +
arch/microblaze/kernel/syscalls/syscall.tbl | 3 +
arch/mips/kernel/syscalls/syscall_n32.tbl | 3 +
arch/mips/kernel/syscalls/syscall_n64.tbl | 3 +
arch/mips/kernel/syscalls/syscall_o32.tbl | 3 +
arch/parisc/kernel/syscalls/syscall.tbl | 3 +
arch/powerpc/kernel/syscalls/syscall.tbl | 3 +
arch/s390/kernel/syscalls/syscall.tbl | 3 +
arch/sh/kernel/syscalls/syscall.tbl | 3 +
arch/sparc/kernel/syscalls/syscall.tbl | 3 +
arch/x86/entry/syscalls/syscall_32.tbl | 3 +
arch/x86/entry/syscalls/syscall_64.tbl | 3 +
arch/xtensa/kernel/syscalls/syscall.tbl | 3 +
include/linux/syscalls.h | 3 +
include/uapi/asm-generic/unistd.h | 9 +-
kernel/sys.c | 138 ++++++++++++++++++
kernel/sys_ni.c | 3 +
scripts/syscall.tbl | 3 +
.../arch/powerpc/entry/syscalls/syscall.tbl | 3 +
.../perf/arch/s390/entry/syscalls/syscall.tbl | 3 +
22 files changed, 206 insertions(+), 1 deletion(-)
--- a/arch/alpha/kernel/syscalls/syscall.tbl
+++ b/arch/alpha/kernel/syscalls/syscall.tbl
@@ -502,3 +502,6 @@
570 common lsm_set_self_attr sys_lsm_set_self_attr
571 common lsm_list_modules sys_lsm_list_modules
572 common mseal sys_mseal
+573 common process_ksm_enable sys_process_ksm_enable
+574 common process_ksm_disable sys_process_ksm_disable
+575 common process_ksm_status sys_process_ksm_status
--- a/arch/arm/tools/syscall.tbl
+++ b/arch/arm/tools/syscall.tbl
@@ -477,3 +477,6 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status
--- a/arch/m68k/kernel/syscalls/syscall.tbl
+++ b/arch/m68k/kernel/syscalls/syscall.tbl
@@ -462,3 +462,6 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status
--- a/arch/microblaze/kernel/syscalls/syscall.tbl
+++ b/arch/microblaze/kernel/syscalls/syscall.tbl
@@ -468,3 +468,6 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status
--- a/arch/mips/kernel/syscalls/syscall_n32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n32.tbl
@@ -401,3 +401,6 @@
460 n32 lsm_set_self_attr sys_lsm_set_self_attr
461 n32 lsm_list_modules sys_lsm_list_modules
462 n32 mseal sys_mseal
+463 n32 process_ksm_enable sys_process_ksm_enable
+464 n32 process_ksm_disable sys_process_ksm_disable
+465 n32 process_ksm_status sys_process_ksm_status
--- a/arch/mips/kernel/syscalls/syscall_n64.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n64.tbl
@@ -377,3 +377,6 @@
460 n64 lsm_set_self_attr sys_lsm_set_self_attr
461 n64 lsm_list_modules sys_lsm_list_modules
462 n64 mseal sys_mseal
+463 n64 process_ksm_enable sys_process_ksm_enable
+464 n64 process_ksm_disable sys_process_ksm_disable
+465 n64 process_ksm_status sys_process_ksm_status
--- a/arch/mips/kernel/syscalls/syscall_o32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_o32.tbl
@@ -450,3 +450,6 @@
460 o32 lsm_set_self_attr sys_lsm_set_self_attr
461 o32 lsm_list_modules sys_lsm_list_modules
462 o32 mseal sys_mseal
+463 o32 process_ksm_enable sys_process_ksm_enable
+464 o32 process_ksm_disable sys_process_ksm_disable
+465 o32 process_ksm_status sys_process_ksm_status
--- a/arch/parisc/kernel/syscalls/syscall.tbl
+++ b/arch/parisc/kernel/syscalls/syscall.tbl
@@ -461,3 +461,6 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status
--- a/arch/powerpc/kernel/syscalls/syscall.tbl
+++ b/arch/powerpc/kernel/syscalls/syscall.tbl
@@ -553,3 +553,6 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status
--- a/arch/s390/kernel/syscalls/syscall.tbl
+++ b/arch/s390/kernel/syscalls/syscall.tbl
@@ -465,3 +465,6 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status sys_process_ksm_status
--- a/arch/sh/kernel/syscalls/syscall.tbl
+++ b/arch/sh/kernel/syscalls/syscall.tbl
@@ -466,3 +466,6 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status
--- a/arch/sparc/kernel/syscalls/syscall.tbl
+++ b/arch/sparc/kernel/syscalls/syscall.tbl
@@ -508,3 +508,6 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -468,3 +468,6 @@
460 i386 lsm_set_self_attr sys_lsm_set_self_attr
461 i386 lsm_list_modules sys_lsm_list_modules
462 i386 mseal sys_mseal
+463 i386 process_ksm_enable sys_process_ksm_enable
+464 i386 process_ksm_disable sys_process_ksm_disable
+465 i386 process_ksm_status sys_process_ksm_status
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -386,6 +386,9 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status
#
# Due to a historical design error, certain syscalls are numbered differently
--- a/arch/xtensa/kernel/syscalls/syscall.tbl
+++ b/arch/xtensa/kernel/syscalls/syscall.tbl
@@ -433,3 +433,6 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -818,6 +818,9 @@ asmlinkage long sys_madvise(unsigned lon
asmlinkage long sys_process_madvise(int pidfd, const struct iovec __user *vec,
size_t vlen, int behavior, unsigned int flags);
asmlinkage long sys_process_mrelease(int pidfd, unsigned int flags);
+asmlinkage long sys_process_ksm_enable(int pidfd, unsigned int flags);
+asmlinkage long sys_process_ksm_disable(int pidfd, unsigned int flags);
+asmlinkage long sys_process_ksm_status(int pidfd, unsigned int flags);
asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
unsigned long prot, unsigned long pgoff,
unsigned long flags);
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -841,8 +841,15 @@ __SYSCALL(__NR_lsm_list_modules, sys_lsm
#define __NR_mseal 462
__SYSCALL(__NR_mseal, sys_mseal)
+#define __NR_process_ksm_enable 463
+__SYSCALL(__NR_process_ksm_enable, sys_process_ksm_enable)
+#define __NR_process_ksm_disable 464
+__SYSCALL(__NR_process_ksm_disable, sys_process_ksm_disable)
+#define __NR_process_ksm_status 465
+__SYSCALL(__NR_process_ksm_status, sys_process_ksm_status)
+
#undef __NR_syscalls
-#define __NR_syscalls 463
+#define __NR_syscalls 466
/*
* 32 bit systems traditionally used different
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2791,6 +2791,144 @@ SYSCALL_DEFINE5(prctl, int, option, unsi
return error;
}
+#ifdef CONFIG_KSM
+enum pkc_action {
+ PKSM_ENABLE = 0,
+ PKSM_DISABLE,
+ PKSM_STATUS,
+};
+
+static long do_process_ksm_control(int pidfd, enum pkc_action action)
+{
+ long ret;
+ struct task_struct *task;
+ struct mm_struct *mm;
+ unsigned int f_flags;
+
+ task = pidfd_get_task(pidfd, &f_flags);
+ if (IS_ERR(task)) {
+ ret = PTR_ERR(task);
+ goto out;
+ }
+
+ /* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
+ mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
+ if (IS_ERR_OR_NULL(mm)) {
+ ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
+ goto release_task;
+ }
+
+ /* Require CAP_SYS_NICE for influencing process performance. */
+ if (!capable(CAP_SYS_NICE)) {
+ ret = -EPERM;
+ goto release_mm;
+ }
+
+ if (mmap_write_lock_killable(mm)) {
+ ret = -EINTR;
+ goto release_mm;
+ }
+
+ switch (action) {
+ case PKSM_ENABLE:
+ ret = ksm_enable_merge_any(mm);
+ break;
+ case PKSM_DISABLE:
+ ret = ksm_disable_merge_any(mm);
+ break;
+ case PKSM_STATUS:
+ ret = !!test_bit(MMF_VM_MERGE_ANY, &mm->flags);
+ break;
+ }
+
+ mmap_write_unlock(mm);
+
+release_mm:
+ mmput(mm);
+release_task:
+ put_task_struct(task);
+out:
+ return ret;
+}
+#endif /* CONFIG_KSM */
+
+SYSCALL_DEFINE2(process_ksm_enable, int, pidfd, unsigned int, flags)
+{
+#ifdef CONFIG_KSM
+ if (flags != 0)
+ return -EINVAL;
+
+ return do_process_ksm_control(pidfd, PKSM_ENABLE);
+#else /* CONFIG_KSM */
+ return -ENOSYS;
+#endif /* CONFIG_KSM */
+}
+
+SYSCALL_DEFINE2(process_ksm_disable, int, pidfd, unsigned int, flags)
+{
+#ifdef CONFIG_KSM
+ if (flags != 0)
+ return -EINVAL;
+
+ return do_process_ksm_control(pidfd, PKSM_DISABLE);
+#else /* CONFIG_KSM */
+ return -ENOSYS;
+#endif /* CONFIG_KSM */
+}
+
+SYSCALL_DEFINE2(process_ksm_status, int, pidfd, unsigned int, flags)
+{
+#ifdef CONFIG_KSM
+ if (flags != 0)
+ return -EINVAL;
+
+ return do_process_ksm_control(pidfd, PKSM_STATUS);
+#else /* CONFIG_KSM */
+ return -ENOSYS;
+#endif /* CONFIG_KSM */
+}
+
+#ifdef CONFIG_KSM
+static ssize_t process_ksm_enable_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%u\n", __NR_process_ksm_enable);
+}
+static struct kobj_attribute process_ksm_enable_attr = __ATTR_RO(process_ksm_enable);
+
+static ssize_t process_ksm_disable_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%u\n", __NR_process_ksm_disable);
+}
+static struct kobj_attribute process_ksm_disable_attr = __ATTR_RO(process_ksm_disable);
+
+static ssize_t process_ksm_status_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%u\n", __NR_process_ksm_status);
+}
+static struct kobj_attribute process_ksm_status_attr = __ATTR_RO(process_ksm_status);
+
+static struct attribute *process_ksm_sysfs_attrs[] = {
+ &process_ksm_enable_attr.attr,
+ &process_ksm_disable_attr.attr,
+ &process_ksm_status_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group process_ksm_sysfs_attr_group = {
+ .attrs = process_ksm_sysfs_attrs,
+ .name = "process_ksm",
+};
+
+static int __init process_ksm_sysfs_init(void)
+{
+ return sysfs_create_group(kernel_kobj, &process_ksm_sysfs_attr_group);
+}
+subsys_initcall(process_ksm_sysfs_init);
+#endif /* CONFIG_KSM */
+
SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep,
struct getcpu_cache __user *, unused)
{
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -186,6 +186,9 @@ COND_SYSCALL(mincore);
COND_SYSCALL(madvise);
COND_SYSCALL(process_madvise);
COND_SYSCALL(process_mrelease);
+COND_SYSCALL(process_ksm_enable);
+COND_SYSCALL(process_ksm_disable);
+COND_SYSCALL(process_ksm_status);
COND_SYSCALL(remap_file_pages);
COND_SYSCALL(mbind);
COND_SYSCALL(get_mempolicy);
--- a/scripts/syscall.tbl
+++ b/scripts/syscall.tbl
@@ -403,3 +403,6 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status
--- a/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl
+++ b/tools/perf/arch/powerpc/entry/syscalls/syscall.tbl
@@ -553,3 +553,6 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status
--- a/tools/perf/arch/s390/entry/syscalls/syscall.tbl
+++ b/tools/perf/arch/s390/entry/syscalls/syscall.tbl
@@ -465,3 +465,6 @@
460 common lsm_set_self_attr sys_lsm_set_self_attr sys_lsm_set_self_attr
461 common lsm_list_modules sys_lsm_list_modules sys_lsm_list_modules
462 common mseal sys_mseal sys_mseal
+463 common process_ksm_enable sys_process_ksm_enable sys_process_ksm_enable
+464 common process_ksm_disable sys_process_ksm_disable sys_process_ksm_disable
+465 common process_ksm_status sys_process_ksm_status sys_process_ksm_status
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