From: Christophe Leroy christophe.leroy@csgroup.eu
[ Upstream commit a03b1a0b19398a47489fdcef02ec19c2ba05a15d ]
Looking at generated code for handle_signal32() shows calls to a function called __unsafe_save_user_regs.constprop.0 while user access is open.
And that __unsafe_save_user_regs.constprop.0 function has two nops at the begining, allowing it to be traced, which is unexpected during user access open window.
The solution could be to mark __unsafe_save_user_regs() no trace, but to be on the safe side the most efficient is to flag it __always_inline as already done for function __unsafe_restore_general_regs(). The function is relatively small and only called twice, so the size increase will remain in the noise.
Do the same with save_tm_user_regs_unsafe() as it may suffer the same issue.
Fixes: ef75e7318294 ("powerpc/signal32: Transform save_user_regs() and save_tm_user_regs() in 'unsafe' version") Signed-off-by: Christophe Leroy christophe.leroy@csgroup.eu Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://msgid.link/7e469c8f01860a69c1ada3ca6a5e2aa65f0f74b2.1685955220.git.c... Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/kernel/signal_32.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c index c114c7f25645c..7a718ed32b277 100644 --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -264,8 +264,9 @@ static void prepare_save_user_regs(int ctx_has_vsx_region) #endif }
-static int __unsafe_save_user_regs(struct pt_regs *regs, struct mcontext __user *frame, - struct mcontext __user *tm_frame, int ctx_has_vsx_region) +static __always_inline int +__unsafe_save_user_regs(struct pt_regs *regs, struct mcontext __user *frame, + struct mcontext __user *tm_frame, int ctx_has_vsx_region) { unsigned long msr = regs->msr;
@@ -364,8 +365,9 @@ static void prepare_save_tm_user_regs(void) current->thread.ckvrsave = mfspr(SPRN_VRSAVE); }
-static int save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame, - struct mcontext __user *tm_frame, unsigned long msr) +static __always_inline int +save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame, + struct mcontext __user *tm_frame, unsigned long msr) { /* Save both sets of general registers */ unsafe_save_general_regs(¤t->thread.ckpt_regs, frame, failed); @@ -444,8 +446,9 @@ static int save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user #else static void prepare_save_tm_user_regs(void) { }
-static int save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame, - struct mcontext __user *tm_frame, unsigned long msr) +static __always_inline int +save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user *frame, + struct mcontext __user *tm_frame, unsigned long msr) { return 0; }