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authorSven Schnelle2021-11-13 20:41:17 +0100
committerHelge Deller2021-11-13 22:10:56 +0100
commit3ec18fc7831e7d79e2d536dd1f3bc0d3ba425e8a (patch)
treec07716bb390f5f21a05b90e9894bba0c21d86a15 /arch/parisc
parent38860b2c8bb1b92f61396eb06a63adff916fc31d (diff)
parisc/entry: fix trace test in syscall exit path
commit 8779e05ba8aa ("parisc: Fix ptrace check on syscall return") fixed testing of TI_FLAGS. This uncovered a bug in the test mask. syscall_restore_rfi is only used when the kernel needs to exit to usespace with single or block stepping and the recovery counter enabled. The test however used _TIF_SYSCALL_TRACE_MASK, which includes a lot of bits that shouldn't be tested here. Fix this by using TIF_SINGLESTEP and TIF_BLOCKSTEP directly. I encountered this bug by enabling syscall tracepoints. Both in qemu and on real hardware. As soon as i enabled the tracepoint (sys_exit_read, but i guess it doesn't really matter which one), i got random page faults in userspace almost immediately. Signed-off-by: Sven Schnelle <svens@stackframe.org> Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to 'arch/parisc')
-rw-r--r--arch/parisc/kernel/entry.S2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index 57944d6f9ebb..88c188a965d8 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -1805,7 +1805,7 @@ syscall_restore:
/* Are we being ptraced? */
LDREG TASK_TI_FLAGS(%r1),%r19
- ldi _TIF_SYSCALL_TRACE_MASK,%r2
+ ldi _TIF_SINGLESTEP|_TIF_BLOCKSTEP,%r2
and,COND(=) %r19,%r2,%r0
b,n syscall_restore_rfi