[PATCH 2/3] m68k: update ->thread.esp0 before calling syscall_trace() in ret_from_signal

Al Viro
2021-07-25T17:21:56Z

We get there when sigreturn has performed obscene acts on kernel stack;
in particular, the location of pt_regs has shifted. We are about to call
syscall_trace(), which might stop for tracer. If that happens, we'd better
have task_pt_regs() returning correct result...

Fucked-up-by: Al Viro <viro@zeniv.linux.org.uk>
Fixes: bd6f56a75bb2 ("m68k: Missing syscall_trace() on sigreturn")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
arch/m68k/kernel/entry.S | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/m68k/kernel/entry.S b/arch/m68k/kernel/entry.S
index 9dd76fbb7c6b..ff9e842cec0f 100644
--- a/arch/m68k/kernel/entry.S
+++ b/arch/m68k/kernel/entry.S
@@ -186,6 +186,8 @@ ENTRY(ret_from_signal)
movel %curptr@(TASK_STACK),%a1
tstb %a1@(TINFO_FLAGS+2)
jge 1f
+ lea %sp@(SWITCH_STACK_SIZE),%a1
+ movel %a1,%curptr@(TASK_THREAD+THREAD_ESP0)
jbsr syscall_trace
1: RESTORE_SWITCH_STACK
addql #4,%sp
--
2.11.0