[RFC kgr on klp 4/9] livepatch: add kgr infrastructure
From: Jiri Slaby
Date: Mon May 04 2015 - 07:41:27 EST
This means:
* add a per-thread flag to indicate whether a task is in the old or in
the new universe,
* reset it in _slow_ paths of syscall's entry/exit,
* add helpers around the flag to sched.h,
* export the status in /proc/<pid>/kgr_in_progress,
This was cherry-picked from the kGraft implementation and will serve
as a base for kGraft-like patching in Live Patching.
Miroslav helped to clean the assembly up and move to C.
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
Cc: Miroslav Benes <mbenes@xxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: linux-s390@xxxxxxxxxxxxxxx
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
---
arch/s390/include/asm/thread_info.h | 2 ++
arch/s390/kernel/Makefile | 1 +
arch/s390/kernel/entry.S | 11 +++++++++++
arch/s390/kernel/livepatch.c | 14 ++++++++++++++
arch/x86/include/asm/thread_info.h | 11 +++++++----
arch/x86/kernel/ptrace.c | 7 +++++++
arch/x86/kernel/signal.c | 5 +++++
fs/proc/base.c | 14 ++++++++++++++
include/linux/sched.h | 23 +++++++++++++++++++++++
9 files changed, 84 insertions(+), 4 deletions(-)
create mode 100644 arch/s390/kernel/livepatch.c
diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h
index 4c27ec764c36..88a559531a7b 100644
--- a/arch/s390/include/asm/thread_info.h
+++ b/arch/s390/include/asm/thread_info.h
@@ -82,6 +82,7 @@ void arch_release_task_struct(struct task_struct *tsk);
#define TIF_SINGLE_STEP 19 /* This task is single stepped */
#define TIF_BLOCK_STEP 20 /* This task is block stepped */
#define TIF_UPROBE_SINGLESTEP 21 /* This task is uprobe single stepped */
+#define TIF_KGR_IN_PROGRESS 22 /* This task has not finished patching */
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
@@ -93,6 +94,7 @@ void arch_release_task_struct(struct task_struct *tsk);
#define _TIF_UPROBE (1<<TIF_UPROBE)
#define _TIF_31BIT (1<<TIF_31BIT)
#define _TIF_SINGLE_STEP (1<<TIF_SINGLE_STEP)
+#define _TIF_KGR_IN_PROGRESS (1<<TIF_KGR_IN_PROGRESS)
#define is_32bit_task() (test_thread_flag(TIF_31BIT))
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index ffb87617a36c..ff3ecac94ebe 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -45,6 +45,7 @@ obj-$(CONFIG_AUDIT) += audit.o
compat-obj-$(CONFIG_AUDIT) += compat_audit.o
obj-$(CONFIG_COMPAT) += compat_linux.o compat_signal.o
obj-$(CONFIG_COMPAT) += compat_wrapper.o $(compat-obj-y)
+obj-$(CONFIG_LIVEPATCH) += livepatch.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-$(CONFIG_KPROBES) += kprobes.o
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 99b44acbfcc7..f4be8e142a50 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -73,6 +73,15 @@ _PIF_WORK = (_PIF_PER_TRAP)
#endif
.endm
+ .macro HANDLE_KGRAFT TI_reg
+#if IS_ENABLED(CONFIG_LIVEPATCH)
+ tm __TI_flags+5(\TI_reg),(_TIF_KGR_IN_PROGRESS >> 16)
+ jz 0f
+ brasl %r14,s390_handle_kgraft
+0:
+#endif
+ .endm
+
.macro LPP newpp
#if IS_ENABLED(CONFIG_KVM)
tm __LC_MACHINE_FLAGS+6,0x20 # MACHINE_FLAG_LPP
@@ -217,6 +226,7 @@ ENTRY(system_call)
mvc __PT_INT_CODE(4,%r11),__LC_SVC_ILC
stg %r14,__PT_FLAGS(%r11)
.Lsysc_do_svc:
+ HANDLE_KGRAFT %r12
lg %r10,__TI_sysc_table(%r12) # address of system call table
llgh %r8,__PT_INT_CODE+2(%r11)
slag %r8,%r8,2 # shift and test for svc 0
@@ -248,6 +258,7 @@ ENTRY(system_call)
jnz .Lsysc_work # check for work
tm __LC_CPU_FLAGS+7,_CIF_WORK
jnz .Lsysc_work
+ HANDLE_KGRAFT %r12
.Lsysc_restore:
lg %r14,__LC_VDSO_PER_CPU
lmg %r0,%r10,__PT_R0(%r11)
diff --git a/arch/s390/kernel/livepatch.c b/arch/s390/kernel/livepatch.c
new file mode 100644
index 000000000000..99ace9df5576
--- /dev/null
+++ b/arch/s390/kernel/livepatch.c
@@ -0,0 +1,14 @@
+/*
+ * livepatch.c - s390-specific Kernel Live Patching Core
+ *
+ * Copyright (C) 2014-2015 SUSE
+ *
+ * This file is licensed under the GPLv2.
+ */
+
+#include <linux/sched.h>
+
+asmlinkage void s390_handle_kgraft(void)
+{
+ klp_kgraft_mark_task_safe(current);
+}
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index b4bdec3e9523..3dad428caa6b 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -106,6 +106,7 @@ struct thread_info {
#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
#define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
#define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
+#define TIF_KGR_IN_PROGRESS 26 /* kGraft patching running */
#define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
#define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
#define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
@@ -129,6 +130,7 @@ struct thread_info {
#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
#define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
+#define _TIF_KGR_IN_PROGRESS (1 << TIF_KGR_IN_PROGRESS)
#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
#define _TIF_ADDR32 (1 << TIF_ADDR32)
@@ -138,7 +140,7 @@ struct thread_info {
#define _TIF_WORK_SYSCALL_ENTRY \
(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
_TIF_SECCOMP | _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT | \
- _TIF_NOHZ)
+ _TIF_NOHZ | _TIF_KGR_IN_PROGRESS)
/* work to do in syscall_trace_leave() */
#define _TIF_WORK_SYSCALL_EXIT \
@@ -149,17 +151,18 @@ struct thread_info {
#define _TIF_WORK_MASK \
(0x0000FFFF & \
~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT| \
- _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU))
+ _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU) | \
+ _TIF_KGR_IN_PROGRESS)
/* work to do on any return to user space */
#define _TIF_ALLWORK_MASK \
((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \
- _TIF_NOHZ)
+ _TIF_NOHZ | _TIF_KGR_IN_PROGRESS)
/* Only used for 64 bit */
#define _TIF_DO_NOTIFY_MASK \
(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | \
- _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE)
+ _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE | _TIF_KGR_IN_PROGRESS)
/* flags to check in __switch_to() */
#define _TIF_WORK_CTXSW \
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index a7bc79480719..454f4734b840 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1527,6 +1527,13 @@ unsigned long syscall_trace_enter_phase1(struct pt_regs *regs, u32 arch)
}
#endif
+#if IS_ENABLED(CONFIG_LIVEPATCH)
+ if (work & _TIF_KGR_IN_PROGRESS) {
+ klp_kgraft_mark_task_safe(current);
+ work &= ~_TIF_KGR_IN_PROGRESS;
+ }
+#endif
+
/* Do our best to finish without phase 2. */
if (work == 0)
return ret; /* seccomp and/or nohz only (ret == 0 here) */
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 1ea14fd53933..d5e38e2161ac 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -730,6 +730,11 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
if (thread_info_flags & _TIF_UPROBE)
uprobe_notify_resume(regs);
+#if IS_ENABLED(CONFIG_LIVEPATCH)
+ if (thread_info_flags & _TIF_KGR_IN_PROGRESS)
+ klp_kgraft_mark_task_safe(current);
+#endif
+
/* deal with pending signal delivery */
if (thread_info_flags & _TIF_SIGPENDING)
do_signal(regs);
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 093ca14f5701..4973ae795abd 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2052,6 +2052,17 @@ static const struct file_operations proc_timers_operations = {
};
#endif /* CONFIG_CHECKPOINT_RESTORE */
+#if IS_ENABLED(CONFIG_LIVEPATCH)
+static int proc_pid_kgr_in_progress(struct seq_file *m,
+ struct pid_namespace *ns, struct pid *pid,
+ struct task_struct *task)
+{
+ seq_printf(m, "%d\n", klp_kgraft_task_in_progress(task));
+
+ return 0;
+}
+#endif /* IS_ENABLED(CONFIG_LIVEPATCH) */
+
static int proc_pident_instantiate(struct inode *dir,
struct dentry *dentry, struct task_struct *task, const void *ptr)
{
@@ -2640,6 +2651,9 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_CHECKPOINT_RESTORE
REG("timers", S_IRUGO, proc_timers_operations),
#endif
+#if IS_ENABLED(CONFIG_LIVEPATCH)
+ ONE("kgr_in_progress", S_IRUSR, proc_pid_kgr_in_progress),
+#endif
};
static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8222ae40ecb0..4c0555261cb1 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -3085,6 +3085,29 @@ static inline void mm_update_next_owner(struct mm_struct *mm)
}
#endif /* CONFIG_MEMCG */
+#if IS_ENABLED(CONFIG_LIVEPATCH)
+static inline void klp_kgraft_mark_task_safe(struct task_struct *p)
+{
+ clear_tsk_thread_flag(p, TIF_KGR_IN_PROGRESS);
+}
+static inline void klp_kgraft_mark_task_in_progress(struct task_struct *p)
+{
+ set_tsk_thread_flag(p, TIF_KGR_IN_PROGRESS);
+}
+
+static inline bool klp_kgraft_task_in_progress(struct task_struct *p)
+{
+ return test_tsk_thread_flag(p, TIF_KGR_IN_PROGRESS);
+}
+#else
+static inline void klp_kgraft_mark_task_safe(struct task_struct *p) { }
+static inline void klp_kgraft_mark_task_in_progress(struct task_struct *p) { }
+static inline bool klp_kgraft_task_in_progress(struct task_struct *p)
+{
+ return false;
+}
+#endif /* IS_ENABLED(CONFIG_LIVEPATCH) */
+
static inline unsigned long task_rlimit(const struct task_struct *tsk,
unsigned int limit)
{
--
2.3.5
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