From: Ammar Faizi ammarfaizi2@gnuweeb.org
This is an RFC patchset v3: sysret_rip test update for Intel FRED architecture.
Xin Li reported sysret_rip test fails at:
assert(ctx->uc_mcontext.gregs[REG_EFL] == ctx->uc_mcontext.gregs[REG_R11]);
On FRED systems, flags is 0x200a93 and r11 is 0xfeedfacedeadbeef here.
We need to remove or change this assertion, maybe: assert(ctx->uc_mcontext.gregs[REG_EFL] == ctx->uc_mcontext.gregs[REG_R11] || r11_sentinel == ctx->uc_mcontext.gregs[REG_R11]);
in a FRED system. Let's handle the FRED system scenario too. The 'syscall' instruction in a FRED system doesn't set %r11=%rflags.
There are two patches in this series.
How to test this:
$ make -C tools/testing/selftests/x86 $ tools/testing/selftests/x86/sysret_rip_64
Link: https://lore.kernel.org/lkml/5d4ad3e3-034f-c7da-d141- 9c001c2343af@intel.com Fixes: 660602140103 ("selftests/x86: Add a selftest for SYSRET to noncanonical addresses") Link: https://lore.kernel.org/lkml/25b96960-a07e-a952-5c23- 786b55054126@zytor.com Reported-by: Xin Li xin3.li@intel.com Co-developed-by: H. Peter Anvin (Intel) hpa@zytor.com Signed-off-by: H. Peter Anvin (Intel) hpa@zytor.com Acked-by: H. Peter Anvin (Intel) hpa@zytor.com Signed-off-by: Ammar Faizi ammarfaizi2@gnuweeb.org
## Changelog v3:
- Test that we don't get a mix of REGS_SAVED and REGS_SYSRET, which is a major part of the point (hpa).
## Changelog v2:
- Use "+r"(rsp) as the right way to avoid redzone problems per Andrew's comment (hpa). (Ref: https://lore.kernel.org/lkml/8f5c24df-514d-5d89-f58f-
ec8c3eb1e049@zytor.com )
Ammar Faizi (2): selftests/x86: sysret_rip: Handle syscall in a FRED system selftests/x86: sysret_rip: Add more syscall tests with respect to `%rcx` and `%r11`
tools/testing/selftests/x86/sysret_rip.c | 120 ++++++++++++++++++++++- 1 file changed, 119 insertions(+), 1 deletion(-)
base-commit: e12ad468c22065a2826b2fc4c11d2113a7975301
Ammar Faizi