Re: [PATCH v3 1/2] powerpc/64s: system call scv tabort fix for corrupt irq soft-mask state

2021-09-19 Thread Michael Ellerman 
On Fri, 3 Sep 2021 22:57:06 +1000, Nicholas Piggin wrote:
> If a system call is made with a transaction active, the kernel
> immediately aborts it and returns. scv system calls disable irqs even
> earlier in their interrupt handler, and tabort_syscall does not fix this
> up.
> 
> This can result in irq soft-mask state being messed up on the next
> kernel entry, and crashing at BUG_ON(arch_irq_disabled_regs(regs)) in
> the kernel exit handlers, or possibly worse.
> 
> [...]

Applied to powerpc/fixes.

[1/2] powerpc/64s: system call scv tabort fix for corrupt irq soft-mask state
  https://git.kernel.org/powerpc/c/b871895b148256f1721bc565d803860242755a0b
[2/2] selftests/powerpc: Add scv versions of the basic TM syscall tests
  https://git.kernel.org/powerpc/c/5379ef2a60431232b9bb01c6d3580b875123d723

cheers

Re: [PATCH v3 1/2] powerpc/64s: system call scv tabort fix for corrupt irq soft-mask state

2021-09-13 Thread kernel test robot 

Please kindly note that this is a powerpc32 build.

Hi Nicholas,

I love your patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v5.14 next-20210903]
[cannot apply to powerpc/next scottwood/next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:
https://github.com/0day-ci/linux/commits/Nicholas-Piggin/powerpc-64s-system-call-scv-tabort-fix-for-corrupt-irq-soft-mask-state/20210903-205907
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
a9c9a6f741cdaa2fa9ba24a790db8d07295761e3
:: branch date: 5 hours ago
:: commit date: 5 hours ago
config: powerpc-randconfig-s032-20210903 (attached as .config)
compiler: powerpc-linux-gcc (GCC) 11.2.0
reproduce:
cd linux
wget 
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O 
make.cross
chmod +x make.cross
# 
https://github.com/0day-ci/linux/commit/3510c8c0951ec7ac98da8d6931df7499ca6c881e
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review 
Nicholas-Piggin/powerpc-64s-system-call-scv-tabort-fix-for-corrupt-irq-soft-mask-state/20210903-205907
git checkout 3510c8c0951ec7ac98da8d6931df7499ca6c881e
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 ./make.cross 
ARCH=powerpc

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot 

All errors (new ones prefixed by >>):

   In file included from arch/powerpc/include/asm/processor.h:11,
from arch/powerpc/include/asm/thread_info.h:40,
from include/linux/thread_info.h:60,
from arch/powerpc/include/asm/ptrace.h:298,
from arch/powerpc/include/asm/hw_irq.h:12,
from arch/powerpc/include/asm/irqflags.h:12,
from include/linux/irqflags.h:16,
from include/asm-generic/cmpxchg-local.h:6,
from arch/powerpc/include/asm/cmpxchg.h:526,
from arch/powerpc/include/asm/atomic.h:11,
from include/linux/atomic.h:7,
from include/linux/rcupdate.h:25,
from include/linux/rculist.h:11,
from include/linux/pid.h:5,
from include/linux/sched.h:14,
from include/linux/context_tracking.h:5,
from arch/powerpc/kernel/interrupt.c:3:
   arch/powerpc/kernel/interrupt.c: In function 'system_call_exception':
>> arch/powerpc/include/asm/reg.h:66:29: error: left shift count >= width of 
type [-Werror=shift-count-overflow]
  66 | #define __MASK(X)   (1UL<<(X))
 | ^~
   arch/powerpc/include/asm/reg.h:1378:61: note: in definition of macro 'mtmsr'
1378 |  : "r" ((unsigned long)(v)) \
 | ^
   arch/powerpc/include/asm/reg.h:115:25: note: in expansion of macro '__MASK'
 115 | #define MSR_TM  __MASK(MSR_TM_LG)   /* Transactional Mem 
Available */
 | ^~
   arch/powerpc/kernel/interrupt.c:153:33: note: in expansion of macro 'MSR_TM'
 153 | mtmsr(mfmsr() | MSR_TM);
 | ^~
   cc1: all warnings being treated as errors


vim +66 arch/powerpc/include/asm/reg.h

14cf11af6cf608 include/asm-powerpc/reg.h Paul Mackerras 2005-09-26  62
9f04b9e327c495 include/asm-powerpc/reg.h Paul Mackerras 2005-10-10  63  #ifdef 
__ASSEMBLY__
9f04b9e327c495 include/asm-powerpc/reg.h Paul Mackerras 2005-10-10  64  #define 
__MASK(X)   (1<<(X))
9f04b9e327c495 include/asm-powerpc/reg.h Paul Mackerras 2005-10-10  65  #else
9f04b9e327c495 include/asm-powerpc/reg.h Paul Mackerras 2005-10-10 @66  #define 
__MASK(X)   (1UL<<(X))
9f04b9e327c495 include/asm-powerpc/reg.h Paul Mackerras 2005-10-10  67  #endif
9f04b9e327c495 include/asm-powerpc/reg.h Paul Mackerras 2005-10-10  68

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-...@lists.01.org

.config.gz
Description: application/gzip

[PATCH v3 1/2] powerpc/64s: system call scv tabort fix for corrupt irq soft-mask state

2021-09-03 Thread Nicholas Piggin 
If a system call is made with a transaction active, the kernel
immediately aborts it and returns. scv system calls disable irqs even
earlier in their interrupt handler, and tabort_syscall does not fix this
up.

This can result in irq soft-mask state being messed up on the next
kernel entry, and crashing at BUG_ON(arch_irq_disabled_regs(regs)) in
the kernel exit handlers, or possibly worse.

This can't easily be fixed in asm because at this point an async irq may
have hit, which is soft-masked and marked pending. The pending interrupt
has to be replayed before returning to userspace. The fix is to move the
tabort_syscall code to C in the main syscall handler, and just skip the
system call but otherwise return as usual, which will take care of the
pending irqs. This also does a bunch of other things including possible
signal delivery to the process, but the doomed transaction should still
be aborted when it is eventually returned to.

The sc system call path is changed to use the new C function as well to
reduce code and path differences. This slows down how quickly system
calls are aborted when called while a transaction is active, which could
potentially impact TM performance. But making any system call is already
bad for performance, and TM is on the way out, so go with simpler over
faster.

Reported-by: Eirik Fuller 
Fixes: 7fa95f9adaee7 ("powerpc/64s: system call support for scv/rfscv 
instructions")
Signed-off-by: Nicholas Piggin 
---

v2 of this fix had a bug where an irq could be soft masked and pending
before we hard disable interrupts in tabort_syscall for the case of
scv (because it enters the kernel with EE enabled). So this actually
requires a pretty large change to fix because we can't replay interrupts
just from this early asm context.

Thanks,
Nick

 arch/powerpc/kernel/interrupt.c| 29 +
 arch/powerpc/kernel/interrupt_64.S | 41 --
 2 files changed, 29 insertions(+), 41 deletions(-)

diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
index 21bbd615ca41..c77c80214ad3 100644
--- a/arch/powerpc/kernel/interrupt.c
+++ b/arch/powerpc/kernel/interrupt.c
@@ -19,6 +19,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 
 #if defined(CONFIG_PPC_ADV_DEBUG_REGS) && defined(CONFIG_PPC32)
@@ -138,6 +139,34 @@ notrace long system_call_exception(long r3, long r4, long 
r5,
 */
irq_soft_mask_regs_set_state(regs, IRQS_ENABLED);
 
+   /*
+* If the system call was made with a transaction active, doom it and
+* return without performing the system call. Unless it was an
+* unsupported scv vector, in which case it's treated like an illegal
+* instruction.
+*/
+   if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) &&
+   unlikely(MSR_TM_TRANSACTIONAL(regs->msr)) &&
+   !trap_is_unsupported_scv(regs)) {
+   /* Enable TM in the kernel, and disable EE (for scv) */
+   hard_irq_disable();
+   mtmsr(mfmsr() | MSR_TM);
+
+   /* tabort, this dooms the transaction, nothing else */
+   asm volatile(".long 0x7c00071d | ((%0) << 16)"
+   :: "r"(TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT));
+
+   /*
+* Userspace will never see the return value. Execution will
+* resume after the tbegin. of the aborted transaction with the
+* checkpointed register state. A context switch could occur
+* or signal delivered to the process before resuming the
+* doomed transaction context, but that should all be handled
+* as expected.
+*/
+   return -ENOSYS;
+   }
+
local_irq_enable();
 
if (unlikely(current_thread_info()->flags & _TIF_SYSCALL_DOTRACE)) {
diff --git a/arch/powerpc/kernel/interrupt_64.S 
b/arch/powerpc/kernel/interrupt_64.S
index d4212d2ff0b5..ec950b08a8dc 100644
--- a/arch/powerpc/kernel/interrupt_64.S
+++ b/arch/powerpc/kernel/interrupt_64.S
@@ -12,7 +12,6 @@
 #include 
 #include 
 #include 
-#include 
 
.section".toc","aw"
 SYS_CALL_TABLE:
@@ -55,12 +54,6 @@ COMPAT_SYS_CALL_TABLE:
.globl system_call_vectored_\name
 system_call_vectored_\name:
 _ASM_NOKPROBE_SYMBOL(system_call_vectored_\name)
-#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
-BEGIN_FTR_SECTION
-   extrdi. r10, r12, 1, (63-MSR_TS_T_LG) /* transaction active? */
-   bne tabort_syscall
-END_FTR_SECTION_IFSET(CPU_FTR_TM)
-#endif
SCV_INTERRUPT_TO_KERNEL
mr  r10,r1
ld  r1,PACAKSAVE(r13)
@@ -247,12 +240,6 @@ _ASM_NOKPROBE_SYMBOL(system_call_common_real)
.globl system_call_common
 system_call_common:
 _ASM_NOKPROBE_SYMBOL(system_call_common)
-#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
-BEGIN_FTR_SECTION
-   extrdi. r10, r12, 1, (63-MSR_TS_T_LG) /* transaction active? */
-   bne