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Merge branch 'ppc-bundle' (bundle from Michael Ellerman) 

Merge powerpc transactional memory fixes from Michael Ellerman:
 "I figured I'd still send you the commits using a bundle to make sure
  it works in case I need to do it again in future"

This fixes transactional memory state restore for powerpc.

* bundle'd patches from Michael Ellerman:
  powerpc/tm: Fix illegal TM state in signal handler
  powerpc/64s: Use emergency stack for kernel TM Bad Thing program checks
This commit is contained in:
Linus Torvalds 2017-10-09 19:08:32 -07:00
parent ff33952e4d 044215d145
commit 529a86e063
2 changed files with 35 additions and 2 deletions
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24
arch/powerpc/kernel/exceptions-64s.S
View File

@ -734,7 +734,29 @@ EXC_REAL(program_check, 0x700, 0x100)
EXC_VIRT(program_check, 0x4700, 0x100, 0x700)
TRAMP_KVM(PACA_EXGEN, 0x700)
EXC_COMMON_BEGIN(program_check_common)
EXCEPTION_PROLOG_COMMON(0x700, PACA_EXGEN)
/*
* It's possible to receive a TM Bad Thing type program check with
* userspace register values (in particular r1), but with SRR1 reporting
* that we came from the kernel. Normally that would confuse the bad
* stack logic, and we would report a bad kernel stack pointer. Instead
* we switch to the emergency stack if we're taking a TM Bad Thing from
* the kernel.
*/
li r10,MSR_PR /* Build a mask of MSR_PR .. */
oris r10,r10,0x200000@h /* .. and SRR1_PROGTM */
and r10,r10,r12 /* Mask SRR1 with that. */
srdi r10,r10,8 /* Shift it so we can compare */
cmpldi r10,(0x200000 >> 8) /* .. with an immediate. */
bne 1f /* If != go to normal path. */
/* SRR1 had PR=0 and SRR1_PROGTM=1, so use the emergency stack */
andi. r10,r12,MSR_PR; /* Set CR0 correctly for label */
/* 3 in EXCEPTION_PROLOG_COMMON */
mr r10,r1 /* Save r1 */
ld r1,PACAEMERGSP(r13) /* Use emergency stack */
subi r1,r1,INT_FRAME_SIZE /* alloc stack frame */
b 3f /* Jump into the macro !! */
1: EXCEPTION_PROLOG_COMMON(0x700, PACA_EXGEN)
bl save_nvgprs
RECONCILE_IRQ_STATE(r10, r11)
addi r3,r1,STACK_FRAME_OVERHEAD

13
arch/powerpc/kernel/signal_64.c
View File

@ -452,9 +452,20 @@ static long restore_tm_sigcontexts(struct task_struct *tsk,
if (MSR_TM_RESV(msr))
return -EINVAL;
/* pull in MSR TM from user context */
/* pull in MSR TS bits from user context */
regs->msr = (regs->msr & ~MSR_TS_MASK) | (msr & MSR_TS_MASK);
/*
* Ensure that TM is enabled in regs->msr before we leave the signal
* handler. It could be the case that (a) user disabled the TM bit
* through the manipulation of the MSR bits in uc_mcontext or (b) the
* TM bit was disabled because a sufficient number of context switches
* happened whilst in the signal handler and load_tm overflowed,
* disabling the TM bit. In either case we can end up with an illegal
* TM state leading to a TM Bad Thing when we return to userspace.
*/
regs->msr |= MSR_TM;
/* pull in MSR LE from user context */
regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);