Re: [PATCH 0/5] Live patching for powerpc

From: Torsten Duwe
Date: Thu Apr 14 2016 - 11:20:41 EST


On Thu, Apr 14, 2016 at 11:08:02PM +1000, Michael Ellerman wrote:
> On Thu, 2016-04-14 at 14:57 +0200, Torsten Duwe wrote:
>
> > FTR: then I still have a few ppc64 hunks floating around to support certain consistency
> > models...
>
> OK. I'm not quite sure what you mean but post them and we'll see I guess :)

It's *roughly* the ppc64 equivalent of Josh Poimboeuf's Mar 25
| [RFC PATCH v1.9 14/14] livepatch: update task universe when exiting kernel
which only considers x86.

It's forward ported from an earlier code base; there's some glue missing,
but here it is, for reference.

Signed-off-by: Torsten Duwe <duwe@xxxxxxx>


diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index b034ecd..3e749f4 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -92,6 +92,7 @@ static inline struct thread_info *current_thread_info(void)
TIF_NEED_RESCHED */
#define TIF_32BIT 4 /* 32 bit binary */
#define TIF_RESTORE_TM 5 /* need to restore TM FP/VEC/VSX */
+#define TIF_KLP_NEED_UPDATE 6 /* kGraft patching in progress */
#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
#define TIF_SINGLESTEP 8 /* singlestepping active */
#define TIF_NOHZ 9 /* in adaptive nohz mode */
@@ -115,8 +116,10 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
#define _TIF_32BIT (1<<TIF_32BIT)
#define _TIF_RESTORE_TM (1<<TIF_RESTORE_TM)
+#define _TIF_KLP_NEED_UPDATE (1<<TIF_KLP_NEED_UPDATE)
#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
+#define _TIF_NOHZ (1<<TIF_NOHZ)
#define _TIF_SECCOMP (1<<TIF_SECCOMP)
#define _TIF_RESTOREALL (1<<TIF_RESTOREALL)
#define _TIF_NOERROR (1<<TIF_NOERROR)
@@ -124,7 +127,7 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_UPROBE (1<<TIF_UPROBE)
#define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT)
#define _TIF_EMULATE_STACK_STORE (1<<TIF_EMULATE_STACK_STORE)
-#define _TIF_NOHZ (1<<TIF_NOHZ)
+
#define _TIF_SYSCALL_DOTRACE (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
_TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
_TIF_NOHZ)
@@ -132,7 +135,8 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_USER_WORK_MASK (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
_TIF_NOTIFY_RESUME | _TIF_UPROBE | \
_TIF_RESTORE_TM)
-#define _TIF_PERSYSCALL_MASK (_TIF_RESTOREALL|_TIF_NOERROR)
+
+#define _TIF_PERSYSCALL_MASK (_TIF_RESTOREALL|_TIF_NOERROR|_TIF_KLP_NEED_UPDATE)

/* Bits in local_flags */
/* Don't move TLF_NAPPING without adjusting the code in entry_32.S */
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 5bbd1bc..17f8a18 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -151,8 +151,8 @@ END_FW_FTR_SECTION_IFSET(FW_FEATURE_SPLPAR)

CURRENT_THREAD_INFO(r11, r1)
ld r10,TI_FLAGS(r11)
- andi. r11,r10,_TIF_SYSCALL_DOTRACE
- bne syscall_dotrace /* does not return */
+ andi. r10,r10,(_TIF_SYSCALL_DOTRACE|_TIF_KLP_NEED_UPDATE)
+ bne- syscall_precall /* does not return */
cmpldi 0,r0,NR_syscalls
bge- syscall_enosys

@@ -245,6 +245,17 @@ syscall_error:
neg r3,r3
std r5,_CCR(r1)
b .Lsyscall_error_cont
+
+syscall_precall:
+ andi. r10,r10,(_TIF_KLP_NEED_UPDATE)
+ beq+ syscall_dotrace
+
+ addi r11,r11,TI_FLAGS
+1: ldarx r12,0,r11
+ andc r12,r12,r10
+ stdcx. r12,0,r11
+ bne- 1b
+ subi r11,r11,TI_FLAGS

/* Traced system call support */
syscall_dotrace: