mig was being invoked without any -arch argument, causing it to assume
the build system’s native architecture, which would be x86_64. This is
not correct for iOS device builds, which use arm64. The -arch argument
must be plumbed to mig for correct behavior.
When building for iOS, mig was being invoked without any -isysroot
argument, causing it to use the root for the build system, which runs
macOS and not iOS. The macOS SDK doesn’t include the ARM definitions
needed for iOS device builds.
<mach/exc.defs> and <mach/mach_exc.defs> depend on a small number of
other .defs files to provide definitions of standard types. All .defs
files are absent from the iOS SDK. These .defs files are borrowed from
xnu and placed in third_party/xnu. An additional --include argument is
added to allow mig to locate these files.
Bug: crashpad:31
Change-Id: I27154310352939ebe2fb6329bbbfda701c369289
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/2159291
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Mark Mentovai <mark@chromium.org>
This updates (and corrects) 8dbbaff2e1a5, which added exc.defs, by
adding mach_exc.defs too.
The difference betwen the exc and mach_exc subsystems is that the |code|
parameter is int[] in exc and int64_t[] in mach_exc. Many exceptions
carry the exception address in code[1], and a 32-bit int results in the
exception address being truncated in exc. No information is lost in
mach_exc, where a 64-bit int64_t is used.
In 8dbbaff2e1a5, I misremembered the type of the |code| parameter as a
type derived from uintptr_t, such as vm_address_t, an integer as wide as
a pointer. I was wrong, and mach_exc is necessary. I also noted that
Apple normally forbids mach_-prefixed interfaces in favor of the
prefix-less ones for the reasons I mentioned, and that, all else being
equal, it was desirable to adhere to the spirit of that convention.
Because neither exc nor mach_exc are available in the SDK, it’s moot
from a technical perspective, as we need to provide our own stubs either
way.
Bug: crashpad:31
Change-Id: Ied1be470e653b2bead1a283cb8b9283d210c328d
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/2159286
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Mark Mentovai <mark@chromium.org>
The iOS SDK doesn’t include a copy of <mach/exc.defs>. It only provides
<mach/exc.h>, which is just the user-side header. To obtain declarations
and implementations of the server-side stubs, a current copy of
<mach/exc.defs> is added to third_party, and the mig action in util is
updated to use it on iOS.
The three other mig subsystems that Crashpad uses are not brought to
iOS:
- mach_exc is identical to exc except it always uses 64-bit quantities
for addresses in place of exc’s use of quantiies sized for native
pointers. Because all iOS work is limited to a single process, there
is no need to consider cross-process operation with variable bitness,
so mach_exc is unnecessary. We’re also only targeting 64-bit for iOS,
so exc will always suffice. This follows the spirit of other
mach_-prefixed routines on iOS, where Apple forbids mach_vm_read to
user applications but permits vm_read.
- notify is primarily used on macOS in the Crashpad handler process to
receive a no-senders notification, which is used to trigger handler
shutdown when it has no more clients. This is not believed to be
useful to Crashpad on iOS, which is restricted to single-process
operation.
- child_port is a Crashpad-specific subsystem used to pass Mach rights
between processes, but is similarly useless when restricted to
single-process operation as on iOS.
Bug: crashpad:31
Change-Id: Id4cb3cdd529814438d378c20702c82c1e89dd2be
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/2154530
Commit-Queue: Mark Mentovai <mark@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
