Replace RDMSR with OUT so that testing single-step #DBs on emulated
instructions can be run in userspace (by modifying IOPL). OUT is also
more interesting in that it is guaranteed to exit to host userspace,
whereas RDMSR will do so if and only if userspace is filtering the target
MSR.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
x86/debug.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/x86/debug.c b/x86/debug.c
index 98bdfe36..4b2fbe97 100644
--- a/x86/debug.c
+++ b/x86/debug.c
@@ -124,14 +124,13 @@ static unsigned long singlestep_basic(void)
static void report_singlestep_emulated_instructions(unsigned long start)
{
- report(n == 7 &&
+ report(n == 6 &&
is_single_step_db(dr6[0]) && db_addr[0] == start &&
is_single_step_db(dr6[1]) && db_addr[1] == start + 1 &&
is_single_step_db(dr6[2]) && db_addr[2] == start + 1 + 3 &&
is_single_step_db(dr6[3]) && db_addr[3] == start + 1 + 3 + 2 &&
- is_single_step_db(dr6[4]) && db_addr[4] == start + 1 + 3 + 2 + 5 &&
- is_single_step_db(dr6[5]) && db_addr[5] == start + 1 + 3 + 2 + 5 + 2 &&
- is_single_step_db(dr6[6]) && db_addr[6] == start + 1 + 3 + 2 + 5 + 2 + 1,
+ is_single_step_db(dr6[4]) && db_addr[4] == start + 1 + 3 + 2 + 2 &&
+ is_single_step_db(dr6[5]) && db_addr[5] == start + 1 + 3 + 2 + 2 + 1,
"Single-step #DB on emulated instructions");
}
@@ -153,8 +152,7 @@ static unsigned long singlestep_emulated_instructions(void)
"1:push %%rax\n\t"
"xor %%rax,%%rax\n\t"
"cpuid\n\t"
- "movl $0x1a0,%%ecx\n\t"
- "rdmsr\n\t"
+ "out %%eax, $0x80\n\t"
"popf\n\t"
"lea 1b,%0\n\t"
: "=r" (start) : : "rax", "ebx", "ecx", "edx"
--
2.34.1.703.g22d0c6ccf7-goog
