[ Upstream commit 897bc3df8c5aebb54c32d831f917592e873d0559 ]
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 linux-kernel.bfrz@manchmal.in-ulm.de Fixes: e1c3743e1a20 ("powerpc/tm: Set MSR[TS] just prior to recheckpoint") Signed-off-by: Breno Leitao leitao@debian.org Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Sasha Levin sashal@kernel.org --- 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 d929afab7b24..bdf2f7b995bb 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -746,12 +746,25 @@ int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5, 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;