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authorJosh Stone <jistone@redhat.com>2015-06-05 14:28:03 -0700
committerCatalin Marinas <catalin.marinas@arm.com>2015-06-08 18:34:21 +0100
commit04d7e098f541769721d7511d56aea4b976fd29fd (patch)
tree5804898ef893055a0ad5321f1ea8c80231842f80 /arch
parentaddc8120a784181cc6410973948eee94ea16f2bd (diff)
arm64: fix missing syscall trace exit
If a syscall is entered without TIF_SYSCALL_TRACE set, then it goes on the fast path. It's then possible to have TIF_SYSCALL_TRACE added in the middle of the syscall, but ret_fast_syscall doesn't check this flag again. This causes a ptrace syscall-exit-stop to be missed. For instance, from a PTRACE_EVENT_FORK reported during do_fork, the tracer might resume with PTRACE_SYSCALL, setting TIF_SYSCALL_TRACE. Now the completion of the fork should have a syscall-exit-stop. Russell King fixed this on arm by re-checking _TIF_SYSCALL_WORK in the fast exit path. Do the same on arm64. Reviewed-by: Will Deacon <will.deacon@arm.com> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Josh Stone <jistone@redhat.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/kernel/entry.S7
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index d369ccff67e2..0eeb1b95c65a 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -611,11 +611,16 @@ ENDPROC(cpu_switch_to)
*/
ret_fast_syscall:
disable_irq // disable interrupts
- ldr x1, [tsk, #TI_FLAGS]
+ ldr x1, [tsk, #TI_FLAGS] // re-check for syscall tracing
+ and x2, x1, #_TIF_SYSCALL_WORK
+ cbnz x2, ret_fast_syscall_trace
and x2, x1, #_TIF_WORK_MASK
cbnz x2, fast_work_pending
enable_step_tsk x1, x2
kernel_exit 0, ret = 1
+ret_fast_syscall_trace:
+ enable_irq // enable interrupts
+ b __sys_trace_return
/*
* Ok, we need to do extra processing, enter the slow path.