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| author |   Sven Schnelle <svens@stackframe.org> | 2021-11-13 20:41:17 +0100 |
|---|---|---|
| committer |   Helge Deller <deller@gmx.de> | 2021-11-13 22:10:56 +0100 |
| commit | 3ec18fc7831e7d79e2d536dd1f3bc0d3ba425e8a (patch) | |
| tree | c07716bb390f5f21a05b90e9894bba0c21d86a15 /arch | |
| parent | parisc: Flush kernel data mapping in set_pte_at() when installing pte for user page (diff) | |
| download | linux-dev-3ec18fc7831e7d79e2d536dd1f3bc0d3ba425e8a.tar.xz linux-dev-3ec18fc7831e7d79e2d536dd1f3bc0d3ba425e8a.zip | |
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')
| -rw-r--r-- | arch/parisc/kernel/entry.S | 2 |
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 |