From 902eca1a0ccfd2661106731db3a74b2304f31217 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Mon, 8 Apr 2019 16:32:38 +1000 Subject: [PATCH] powerpc/tm: Limit TM code inside PPC_TRANSACTIONAL_MEM commit 897bc3df8c5aebb54c32d831f917592e873d0559 upstream. Commit e1c3743e1a20 ("powerpc/tm: Set MSR[TS] just prior to recheckpoint") moved a code block around and this block uses a 'msr' variable outside of the CONFIG_PPC_TRANSACTIONAL_MEM, however the 'msr' variable is declared inside a CONFIG_PPC_TRANSACTIONAL_MEM block, causing a possible error when CONFIG_PPC_TRANSACTION_MEM is not defined. error: 'msr' undeclared (first use in this function) This is not causing a compilation error in the mainline kernel, because 'msr' is being used as an argument of MSR_TM_ACTIVE(), which is defined as the following when CONFIG_PPC_TRANSACTIONAL_MEM is *not* set: #define MSR_TM_ACTIVE(x) 0 This patch just fixes this issue avoiding the 'msr' variable usage outside the CONFIG_PPC_TRANSACTIONAL_MEM block, avoiding trusting in the MSR_TM_ACTIVE() definition. Cc: stable@vger.kernel.org Reported-by: Christoph Biedl Fixes: e1c3743e1a20 ("powerpc/tm: Set MSR[TS] just prior to recheckpoint") Signed-off-by: Breno Leitao Signed-off-by: Michael Ellerman Signed-off-by: Michael Neuling Signed-off-by: Sasha Levin --- arch/powerpc/kernel/signal_64.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index bbd1c73243d7..14b0f5b6a373 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -755,12 +755,25 @@ SYSCALL_DEFINE0(rt_sigreturn) if (restore_tm_sigcontexts(current, &uc->uc_mcontext, &uc_transact->uc_mcontext)) goto badframe; - } - else - /* Fall through, for non-TM restore */ + } else #endif - if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) - goto badframe; + { + /* + * Fall through, for non-TM restore + * + * Unset MSR[TS] on the thread regs since MSR from user + * context does not have MSR active, and recheckpoint was + * not called since restore_tm_sigcontexts() was not called + * also. + * + * If not unsetting it, the code can RFID to userspace with + * MSR[TS] set, but without CPU in the proper state, + * causing a TM bad thing. + */ + current->thread.regs->msr &= ~MSR_TS_MASK; + if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) + goto badframe; + } if (restore_altstack(&uc->uc_stack)) goto badframe; -- GitLab