On 05.02.2017 07:10, Andrew Wesie wrote:
On Windows, RDI and RSI are callee-saved registers, but on Linux they are caller-saved registers. As such, raise_func_trampoline needs to explicitly unwind them.
Signed-off-by: Andrew Wesie awesie@gmail.com
dlls/ntdll/signal_x86_64.c | 12 +++++++++--- dlls/ntdll/tests/exception.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 51 insertions(+), 3 deletions(-)
diff --git a/dlls/ntdll/signal_x86_64.c b/dlls/ntdll/signal_x86_64.c index af16cfd..8b85be7 100644 --- a/dlls/ntdll/signal_x86_64.c +++ b/dlls/ntdll/signal_x86_64.c @@ -2067,9 +2067,11 @@ NTSTATUS context_from_server( CONTEXT *to, const context_t *from ) extern void raise_func_trampoline( EXCEPTION_RECORD *rec, CONTEXT *context, raise_func func ); __ASM_GLOBAL_FUNC( raise_func_trampoline, __ASM_CFI(".cfi_signal_frame\n\t")
__ASM_CFI(".cfi_def_cfa %rbp,144\n\t") /* red zone + rip + rbp */__ASM_CFI(".cfi_rel_offset %rip,8\n\t")__ASM_CFI(".cfi_rel_offset %rbp,0\n\t")
__ASM_CFI(".cfi_def_cfa %rbp,160\n\t") /* red zone + rip + rbp + rdi + rsi */__ASM_CFI(".cfi_rel_offset %rip,24\n\t")__ASM_CFI(".cfi_rel_offset %rbp,16\n\t")__ASM_CFI(".cfi_rel_offset %rdi,8\n\t")__ASM_CFI(".cfi_rel_offset %rsi,0\n\t") "call *%rdx\n\t" "int $3")@@ -2086,6 +2088,8 @@ static EXCEPTION_RECORD *setup_exception( ucontext_t *sigcontext, raise_func fun { CONTEXT context; EXCEPTION_RECORD rec;
ULONG64 rsi;ULONG64 rdi; ULONG64 rbp; ULONG64 rip; ULONG64 red_zone[16];@@ -2155,6 +2159,8 @@ static EXCEPTION_RECORD *setup_exception( ucontext_t *sigcontext, raise_func fun rsp_ptr = (ULONG64 *)RSP_sig(sigcontext) - 16; *(--rsp_ptr) = RIP_sig(sigcontext); *(--rsp_ptr) = RBP_sig(sigcontext);
- *(--rsp_ptr) = RDI_sig(sigcontext);
- *(--rsp_ptr) = RSI_sig(sigcontext);
Good catch!
/* now modify the sigcontext to return to the raise function */ RIP_sig(sigcontext) = (ULONG_PTR)raise_func_trampoline;diff --git a/dlls/ntdll/tests/exception.c b/dlls/ntdll/tests/exception.c index dc8f1e2..80c22d0 100644 --- a/dlls/ntdll/tests/exception.c +++ b/dlls/ntdll/tests/exception.c @@ -2073,6 +2073,47 @@ static DWORD run_exception_test(void *handler, const void* context, return result; }
+static DWORD WINAPI unwind_rdi_rsi_handler( EXCEPTION_RECORD *rec, ULONG64 frame,
CONTEXT *context, DISPATCHER_CONTEXT *dispatcher )+{
- if (rec->ExceptionCode != STATUS_BREAKPOINT)
return ExceptionContinueSearch;- RtlUnwind( (PVOID)context->Rsp, (PVOID)(context->Rip + 1), rec, NULL );
Is it safe to assume that this will always work? Unwinding past the unwind_rdi_rsi_handler function might require unwinding information, but I'm not sure if we have that when compiling with mingw? I thought this was not implemented yet. On the testbot it still passed, probably because it was luckily compiled to a simple leaf function.
- return ExceptionContinueSearch;
+}
+static const BYTE unwind_rdi_test_code[] = {
0x57, /* push %rdi */0x48, 0xc7, 0xc7, 0x55, 0x55, 0x55, 0x55, /* mov $0x55555555, %rdi */0xcc, /* int3 */0x48, 0x89, 0xf8, /* mov %rdi, %rax */0x5f, /* pop %rdi */0xc3, /* ret */+};
+static const BYTE unwind_rsi_test_code[] = {
0x56, /* push %rsi */0x48, 0xc7, 0xc6, 0x33, 0x33, 0x33, 0x33, /* mov $0x33333333, %rsi */0xcc, /* int3 */0x48, 0x89, 0xf0, /* mov %rsi, %rax */0x5e, /* pop %rsi */0xc3, /* ret */+};
+static void test_unwind_rdi_rsi(void) +{
- DWORD result;
- result = run_exception_test(unwind_rdi_rsi_handler, NULL, unwind_rdi_test_code,
sizeof(unwind_rdi_test_code), 0);- ok( result == 0x55555555, "expected %x, got %x\n", 0x55555555, result );
- result = run_exception_test(unwind_rdi_rsi_handler, NULL, unwind_rsi_test_code,
sizeof(unwind_rsi_test_code), 0);- ok( result == 0x33333333, "expected %x, got %x\n", 0x33333333, result );
+}
static DWORD WINAPI dr7_handler( EXCEPTION_RECORD *rec, ULONG64 frame, CONTEXT *context, DISPATCHER_CONTEXT *dispatcher ) { @@ -2651,6 +2692,7 @@ START_TEST(exception) test_virtual_unwind(); test___C_specific_handler(); test_restore_context();
test_unwind_rdi_rsi();
if (pRtlAddFunctionTable && pRtlDeleteFunctionTable && pRtlInstallFunctionTableCallback && pRtlLookupFunctionEntry) test_dynamic_unwind();
-
Sebastian Lackner