| Message ID | 20230314192756.217966-1-ardb@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | ARM: vfp: Switch to C API to en/disable softirqs | expand |
On Tue, Mar 14, 2023 at 08:27:53PM +0100, Ard Biesheuvel wrote: > As it turns out, enabling or disabling softirqs from asm code is more > tricky than it looks. Simply bumping the associated bit in preempt_count > does the trick for uninstrumented kernels, but with lockdep or preempt > debug enabled, we really need to call the C versions, as replicating > their behavior in asm fully is intractible. > > So let's rework the existing code a little bit so we can interpose a > little C helper 'vfp_entry()' that disables softirqs before calling the > existing vfpstate handling code in asm. Re-enabling softirqs from asm > code is more straight-forward, as we can simply perform a tail call via > a C routine that is guaranteed to be callable as a function. > > Cc: Frederic Weisbecker <frederic@kernel.org> > Cc: Guenter Roeck <linux@roeck-us.net> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Linus Walleij <linus.walleij@linaro.org> > Link: https://lore.kernel.org/all/ZBBYCSZUJOWBg1s8@localhost.localdomain/ > For the series: Tested-by: Guenter Roeck <linux@roeck-us.net> Series applied on top of v6.3-rc2. Tested with 300+ boot tests on all arm qemu machines in my test bed. Cross-check: Without this series, a warning backtrace is observed roughly once per ~20 boot attempts. Thanks, Guenter > Ard Biesheuvel (3): > ARM: vfp: Pass thread_info pointer to vfp_support_entry > ARM: vfp: Pass successful return address via register R3 > ARM: vfp: Fix broken softirq handling with instrumentation enabled > > arch/arm/include/asm/assembler.h | 13 --------- > arch/arm/vfp/entry.S | 17 ++--------- > arch/arm/vfp/vfphw.S | 30 +++++++++++--------- > arch/arm/vfp/vfpmodule.c | 27 ++++++++++++++---- > 4 files changed, 42 insertions(+), 45 deletions(-) > > -- > 2.39.2 >