Re: [PATCH v4] Add dll trampoline code handling for windows 64bit

Pedro Alves
2012-07-27T17:25:52Z

Hi Kai,

On 07/25/2012 06:57 PM, Kai Tietz wrote:
> Hello,
>
> I have now this patch for a while on my radar. I contacted Roland
> Schwingel about the status of his paperwork with FSF, and he told me
> that he completed it.

Thanks.

> So I want to ping this patch for him, as he
> isn't able to ping on that patch himself for the next week(s).

A patch with the comments addressed would have been better than just a ping. ;-)

>>> 2012-04-02 Roland Schwingel <roland.schwingel@onevision.com>
>>
>> Should be two spaces after your name.
>>

>>> +/* Check win64 DLL jmp trampolines and find jump destination. */
>>
>> The correct spelling is "Win64" capitalized.

>>> static void
>>> amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
>>> {
>>> struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
>>>
>>> + /* Register trampoline handling code. */
>>> + set_gdbarch_skip_trampoline_code (gdbarch, amd64_windows_skip_trampoline_code);
>>
>> A nit, but it'd be cleaner/clearer to put this after the amd64_init_abi call, or
>> better, near the end of the function, after set_gdbarch_skip_main_prologue. The current
>> code reads "initialize the base arch, then install overrides.". This new call
>> here breaks that flow.
>>
>>> +
>>> amd64_init_abi (info, gdbarch);

I confirm his paperwork is okay. I've done the changes mentioned above, and
also a few other formatting fixes. I've checked it in, as below.

2012-07-27 Roland Schwingel <roland.schwingel@onevision.com>

* amd64-windows-tdep.c: Include "frame.h".
(amd64_windows_skip_trampoline_code): New function.
(amd64_windows_init_abi): Add trampoline registration.

---

gdb/amd64-windows-tdep.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)

diff --git a/gdb/amd64-windows-tdep.c b/gdb/amd64-windows-tdep.c
index 41e0efa..528fbb6 100644
--- a/gdb/amd64-windows-tdep.c
+++ b/gdb/amd64-windows-tdep.c
@@ -24,6 +24,7 @@
#include "gdbcore.h"
#include "regcache.h"
#include "windows-tdep.h"
+#include "frame.h"

/* The registers used to pass integer arguments during a function call. */
static int amd64_windows_dummy_call_integer_regs[] =
@@ -154,6 +155,40 @@ amd64_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
return pc;
}

+/* Check Win64 DLL jmp trampolines and find jump destination. */
+
+static CORE_ADDR
+amd64_windows_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
+{
+ CORE_ADDR destination = 0;
+ struct gdbarch *gdbarch = get_frame_arch (frame);
+ enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+
+ /* Check for jmp *<offset>(%rip) (jump near, absolute indirect (/4)). */
+ if (pc && read_memory_unsigned_integer (pc, 2, byte_order) == 0x25ff)
+ {
+ /* Get opcode offset and see if we can find a reference in our data. */
+ ULONGEST offset
+ = read_memory_unsigned_integer (pc + 2, 4, byte_order);
+
+ /* Get address of function pointer at end of pc. */
+ CORE_ADDR indirect_addr = pc + offset + 6;
+
+ struct minimal_symbol *indsym
+ = indirect_addr ? lookup_minimal_symbol_by_pc (indirect_addr) : NULL;
+ const char *symname = indsym ? SYMBOL_LINKAGE_NAME (indsym) : NULL;
+
+ if (symname)
+ {
+ if (strncmp (symname, "__imp_", 6) == 0
+ || strncmp (symname, "_imp_", 5) == 0)
+ destination
+ = read_memory_unsigned_integer (indirect_addr, 8, byte_order);
+ }
+ }
+
+ return destination;
+}

static void
amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
@@ -174,6 +209,8 @@ amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
tdep->integer_param_regs_saved_in_caller_frame = 1;
set_gdbarch_return_value (gdbarch, amd64_windows_return_value);
set_gdbarch_skip_main_prologue (gdbarch, amd64_skip_main_prologue);
+ set_gdbarch_skip_trampoline_code (gdbarch,
+ amd64_windows_skip_trampoline_code);

set_gdbarch_iterate_over_objfiles_in_search_order
(gdbarch, windows_iterate_over_objfiles_in_search_order);