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112 lines
3.5 KiB
Diff
112 lines
3.5 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Brian Gianforcaro <b.gianfo@gmail.com>
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Date: Sun, 20 Feb 2022 00:32:51 -0800
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Subject: [PATCH] serenity: Implement custom wait override for the
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serenity_nat_target
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While troubleshooting why gdb wasn't working when attempting to debug
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serenity programs I noticed two things:
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- The contract of serenity's `waitpid(..)` appears to be slightly
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different than the generic ptrace target expects. We need to make
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sure we pass `WSTOPPED`, and it can return different errno values
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that we would want to re-try on.
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- The contract of serenity's `ptrace(..)` implementation appears to
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diverge as well, as we are expected to call `PT_ATTACH` before we
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call `PT_CONTINUE`, otherwise `ptrace(..)` will just error out.
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Allow gdb to understand these differences, I've overloaded the
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serenity_nat_target::wait(..) method and added the logic there.
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---
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gdb/serenity-nat.c | 62 +++++++++++++++++++++++++++++++++++++++++++++-
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gdb/serenity-nat.h | 4 +++
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2 files changed, 65 insertions(+), 1 deletion(-)
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diff --git a/gdb/serenity-nat.c b/gdb/serenity-nat.c
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index ff740d4..b1d39d4 100644
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--- a/gdb/serenity-nat.c
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+++ b/gdb/serenity-nat.c
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@@ -10,4 +10,64 @@
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#include "gdbsupport/gdb_wait.h"
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#include "inf-child.h"
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-#include "serenity-nat.h"
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\ No newline at end of file
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+#include "serenity-nat.h"
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+
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+ptid_t serenity_nat_target::wait (ptid_t ptid, struct target_waitstatus* ourstatus, target_wait_flags)
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+{
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+ int pid;
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+ int status, save_errno;
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+
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+ do
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+ {
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+ set_sigint_trap ();
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+
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+ do
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+ {
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+ errno = 0;
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+ pid = waitpid (ptid.pid (), &status, WSTOPPED);
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+ if (errno != 0)
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+ {
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+ save_errno = errno;
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+ perror_with_name (("waitpid"));
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+ }
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+ }
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+ while (pid == -1 && (save_errno == EINTR || save_errno == EAGAIN));
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+
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+ clear_sigint_trap ();
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+
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+ if (pid == -1)
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+ {
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+ fprintf_unfiltered (gdb_stderr,
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+ _("Child process unexpectedly missing: %s.\n"),
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+ safe_strerror (save_errno));
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+
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+ /* Claim it exited with unknown signal. */
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+ ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
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+ ourstatus->value.sig = GDB_SIGNAL_UNKNOWN;
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+ return inferior_ptid;
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+ }
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+
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+ /* Ignore terminated detached child processes. */
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+ if (!WIFSTOPPED (status) && find_inferior_pid (this, pid) == nullptr)
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+ pid = -1;
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+ }
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+ while (pid == -1);
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+
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+ store_waitstatus (ourstatus, status);
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+
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+ /* Serenity requires us to PT_ATTACH before we PT_CONTINUE, however GDB doesn't
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+ * provide a hook for us to do that before we issue the PT_CONTINUE, so we are
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+ * forced to do it here.
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+ */
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+ if (!m_attach_before_continue_called) {
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+ errno = 0;
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+ ptrace (PT_ATTACH, pid, (PTRACE_TYPE_ARG3)0, 0);
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+ if (errno != 0) {
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+ save_errno = errno;
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+ printf_unfiltered (_("PT_ATTACH failed: %d - %s \n"), save_errno, safe_strerror (save_errno));
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+ }
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+ m_attach_before_continue_called = true;
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+ }
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+
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+ return ptid_t (pid);
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+}
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diff --git a/gdb/serenity-nat.h b/gdb/serenity-nat.h
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index dcd24ce..9ae3b87 100644
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--- a/gdb/serenity-nat.h
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+++ b/gdb/serenity-nat.h
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@@ -11,6 +11,10 @@
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class serenity_nat_target : public inf_ptrace_target
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{
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+ ptid_t wait (ptid_t, struct target_waitstatus *, target_wait_flags) override;
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+
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+private:
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+ bool m_attach_before_continue_called { false };
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};
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#endif /* serenity-nat.h */
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