Re: [PATCH v4 0/2] x86/fred: Prevent single-step upon ERETU completion

[Sohil Mehta <sohil.mehta@intel.com>]

On 6/5/2025 12:32 PM, Sohil Mehta wrote:
> On 6/5/2025 11:10 AM, Xin Li (Intel) wrote:
> 
>>
>> Xin Li (Intel) (2):
>>   x86/fred/signal: Prevent single-step upon ERETU completion
>>   selftests/x86: Add a test to detect infinite sigtrap handler loop
>>
> 
> I tested the patches on a machine that supports FRED. The results are as
> expected:
> 

Seeing a split lock warning when running the test:
x86/split lock detection: #DB: sigtrap_loop_64/4614 took a bus_lock trap
at address: 0x4011ae

Wanted to get this out sooner for awareness. Will figure out more
details and send out an update.

> FRED on  — no Fix   => FAIL
> FRED off — no Fix   => PASS
> FRED on  — with Fix => PASS
> FRED off — with Fix => PASS
> 
> Tested-by: Sohil Mehta <sohil.mehta@intel.com>
> 
> Though, I haven't tested the 32-bit version of the selftest.
> 
>>  arch/x86/include/asm/sighandling.h         | 22 +++++
>>  arch/x86/kernel/signal_32.c                |  4 +
>>  arch/x86/kernel/signal_64.c                |  4 +
>>  tools/testing/selftests/x86/Makefile       |  2 +-
>>  tools/testing/selftests/x86/sigtrap_loop.c | 97 ++++++++++++++++++++++
>>  5 files changed, 128 insertions(+), 1 deletion(-)
>>  create mode 100644 tools/testing/selftests/x86/sigtrap_loop.c
>>