From: Paul Burton paul.burton@mips.com
commit 5a267832c2ec47b2dad0fdb291a96bb5b8869315 upstream.
The generic nmi_cpu_backtrace() function calls show_regs() when a struct pt_regs is available, and dump_stack() otherwise. If we were to make use of the generic nmi_cpu_backtrace() with MIPS' current implementation of show_regs() this would mean that we see only register data with no accompanying stack information, in contrast with our current implementation which calls dump_stack() regardless of whether register state is available.
In preparation for making use of the generic nmi_cpu_backtrace() to implement arch_trigger_cpumask_backtrace(), have our implementation of show_regs() call dump_stack() and drop the explicit dump_stack() call in arch_dump_stack() which is invoked by arch_trigger_cpumask_backtrace().
This will allow the output we produce to remain the same after a later patch switches to using nmi_cpu_backtrace(). It may mean that we produce extra stack output in other uses of show_regs(), but this:
1) Seems harmless. 2) Is good for consistency between arch_trigger_cpumask_backtrace() and other users of show_regs(). 3) Matches the behaviour of the ARM & PowerPC architectures.
Marked for stable back to v4.9 as a prerequisite of the following patch "MIPS: Call dump_stack() from show_regs()".
Signed-off-by: Paul Burton paul.burton@mips.com Patchwork: https://patchwork.linux-mips.org/patch/19596/ Cc: James Hogan jhogan@kernel.org Cc: Ralf Baechle ralf@linux-mips.org Cc: Huacai Chen chenhc@lemote.com Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org [ Huacai: backported to 4.4: The next patch is also backported to 4.4 ] Signed-off-by: Huacai Chen chenhc@lemote.com --- arch/mips/kernel/process.c | 4 ++-- arch/mips/kernel/traps.c | 1 + 2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index 1ee603d..f96048a 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -637,8 +637,8 @@ static void arch_dump_stack(void *info)
if (regs) show_regs(regs); - - dump_stack(); + else + dump_stack(); }
void arch_trigger_all_cpu_backtrace(bool include_self) diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index 31ca2ed..1b90121 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -344,6 +344,7 @@ static void __show_regs(const struct pt_regs *regs) void show_regs(struct pt_regs *regs) { __show_regs((struct pt_regs *)regs); + dump_stack(); }
void show_registers(struct pt_regs *regs)