[3/8] FreeBSD x86: Remove fallback for detecting signal trampolines by address.

Message ID 20210714140741.6460-4-jhb@FreeBSD.org
State New
Headers show
Series
  • Switch FreeBSD x86 to using register maps for GP registers
Related show

Commit Message

John Baldwin July 14, 2021, 2:07 p.m.
A few FreeBSD releases did not include the page holding the signal
code in core dumps.  As a workaround, a sysctl was used to fetch the
default location of the signal code instead.  The youngest affected
FreeBSD release is 10.1 released in November 2014 and EOLed in
December 2016.  The fallback only works for native processes and would
require a separate unwinder once the FreeBSD arches are converted to
use tramp_frame for signal frames.
---
 gdb/amd64-fbsd-nat.c  | 28 ----------------------------
 gdb/amd64-fbsd-tdep.c |  6 ------
 gdb/amd64-tdep.h      |  2 --
 gdb/i386-fbsd-nat.c   | 26 --------------------------
 gdb/i386-fbsd-tdep.c  |  8 --------
 gdb/i386-tdep.h       |  2 --
 6 files changed, 72 deletions(-)

-- 
2.31.1

Patch

diff --git a/gdb/amd64-fbsd-nat.c b/gdb/amd64-fbsd-nat.c
index bd3687b69c..44dfb5a18f 100644
--- a/gdb/amd64-fbsd-nat.c
+++ b/gdb/amd64-fbsd-nat.c
@@ -278,32 +278,4 @@  Please report this to <bug-gdb@gnu.org>."),
     }
 
   SC_RBP_OFFSET = offset;
-
-#ifdef KERN_PROC_SIGTRAMP
-  /* Normally signal frames are detected via amd64fbsd_sigtramp_p.
-     However, FreeBSD 9.2 through 10.1 do not include the page holding
-     the signal code in core dumps.  These releases do provide a
-     kern.proc.sigtramp.<pid> sysctl that returns the location of the
-     signal trampoline for a running process.  We fetch the location
-     of the current (gdb) process and use this to identify signal
-     frames in core dumps from these releases.  Note that this only
-     works for core dumps of 64-bit (FreeBSD/amd64) processes and does
-     not handle core dumps of 32-bit (FreeBSD/i386) processes.  */
-  {
-    int mib[4];
-    struct kinfo_sigtramp kst;
-    size_t len;
-
-    mib[0] = CTL_KERN;
-    mib[1] = KERN_PROC;
-    mib[2] = KERN_PROC_SIGTRAMP;
-    mib[3] = getpid ();
-    len = sizeof (kst);
-    if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0)
-      {
-	amd64fbsd_sigtramp_start_addr = (uintptr_t) kst.ksigtramp_start;
-	amd64fbsd_sigtramp_end_addr = (uintptr_t) kst.ksigtramp_end;
-      }
-  }
-#endif
 }
diff --git a/gdb/amd64-fbsd-tdep.c b/gdb/amd64-fbsd-tdep.c
index 289431306a..e8ad246f61 100644
--- a/gdb/amd64-fbsd-tdep.c
+++ b/gdb/amd64-fbsd-tdep.c
@@ -117,10 +117,6 @@  static int amd64fbsd_r_reg_offset[] =
   -1				/* %gs */
 };
 
-/* Location of the signal trampoline.  */
-CORE_ADDR amd64fbsd_sigtramp_start_addr;
-CORE_ADDR amd64fbsd_sigtramp_end_addr;
-
 /* From <machine/signal.h>.  */
 int amd64fbsd_sc_reg_offset[] =
 {
@@ -245,8 +241,6 @@  amd64fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 		  amd64_target_description (X86_XSTATE_SSE_MASK, true));
 
   tdep->sigtramp_p = amd64fbsd_sigtramp_p;
-  tdep->sigtramp_start = amd64fbsd_sigtramp_start_addr;
-  tdep->sigtramp_end = amd64fbsd_sigtramp_end_addr;
   tdep->sigcontext_addr = amd64fbsd_sigcontext_addr;
   tdep->sc_reg_offset = amd64fbsd_sc_reg_offset;
   tdep->sc_num_regs = ARRAY_SIZE (amd64fbsd_sc_reg_offset);
diff --git a/gdb/amd64-tdep.h b/gdb/amd64-tdep.h
index 6faa399ceb..b2a29aa5f8 100644
--- a/gdb/amd64-tdep.h
+++ b/gdb/amd64-tdep.h
@@ -145,8 +145,6 @@  extern int amd64nbsd_r_reg_offset[];
 extern int amd64obsd_r_reg_offset[];
 
 /* Variables exported from amd64-fbsd-tdep.c.  */
-extern CORE_ADDR amd64fbsd_sigtramp_start_addr;
-extern CORE_ADDR amd64fbsd_sigtramp_end_addr;
 extern int amd64fbsd_sc_reg_offset[];
 
 #endif /* amd64-tdep.h */
diff --git a/gdb/i386-fbsd-nat.c b/gdb/i386-fbsd-nat.c
index f15fd625b1..9b5913d88e 100644
--- a/gdb/i386-fbsd-nat.c
+++ b/gdb/i386-fbsd-nat.c
@@ -182,30 +182,4 @@  _initialize_i386fbsd_nat ()
 
   /* Support debugging kernel virtual memory images.  */
   bsd_kvm_add_target (i386fbsd_supply_pcb);
-
-#ifdef KERN_PROC_SIGTRAMP
-  /* Normally signal frames are detected via i386fbsd_sigtramp_p.
-     However, FreeBSD 9.2 through 10.1 do not include the page holding
-     the signal code in core dumps.  These releases do provide a
-     kern.proc.sigtramp.<pid> sysctl that returns the location of the
-     signal trampoline for a running process.  We fetch the location
-     of the current (gdb) process and use this to identify signal
-     frames in core dumps from these releases.  */
-  {
-    int mib[4];
-    struct kinfo_sigtramp kst;
-    size_t len;
-
-    mib[0] = CTL_KERN;
-    mib[1] = KERN_PROC;
-    mib[2] = KERN_PROC_SIGTRAMP;
-    mib[3] = getpid ();
-    len = sizeof (kst);
-    if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0)
-      {
-	i386fbsd_sigtramp_start_addr = (uintptr_t) kst.ksigtramp_start;
-	i386fbsd_sigtramp_end_addr = (uintptr_t) kst.ksigtramp_end;
-      }
-  }
-#endif
 }
diff --git a/gdb/i386-fbsd-tdep.c b/gdb/i386-fbsd-tdep.c
index 6248eaf1c4..4d235541ea 100644
--- a/gdb/i386-fbsd-tdep.c
+++ b/gdb/i386-fbsd-tdep.c
@@ -122,10 +122,6 @@  static int i386fbsd_r_reg_offset[] =
   2 * 4, 1 * 4, 0 * 4, 18 * 4	/* %ds, %es, %fs, %gs */
 };
 
-/* Sigtramp routine location.  */
-CORE_ADDR i386fbsd_sigtramp_start_addr;
-CORE_ADDR i386fbsd_sigtramp_end_addr;
-
 /* From <machine/signal.h>.  */
 int i386fbsd_sc_reg_offset[] =
 {
@@ -292,10 +288,6 @@  i386fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 
   tdep->sigtramp_p = i386fbsd_sigtramp_p;
 
-  /* FreeBSD uses a different memory layout.  */
-  tdep->sigtramp_start = i386fbsd_sigtramp_start_addr;
-  tdep->sigtramp_end = i386fbsd_sigtramp_end_addr;
-
   /* FreeBSD has a more complete `struct sigcontext'.  */
   tdep->sc_reg_offset = i386fbsd_sc_reg_offset;
   tdep->sc_num_regs = ARRAY_SIZE (i386fbsd_sc_reg_offset);
diff --git a/gdb/i386-tdep.h b/gdb/i386-tdep.h
index 4c45a9a75d..92f0257916 100644
--- a/gdb/i386-tdep.h
+++ b/gdb/i386-tdep.h
@@ -472,8 +472,6 @@  extern int i386_mpx_enabled (void);
 /* Functions and variables exported from i386-bsd-tdep.c.  */
 
 extern void i386bsd_init_abi (struct gdbarch_info, struct gdbarch *);
-extern CORE_ADDR i386fbsd_sigtramp_start_addr;
-extern CORE_ADDR i386fbsd_sigtramp_end_addr;
 extern CORE_ADDR i386obsd_sigtramp_start_addr;
 extern CORE_ADDR i386obsd_sigtramp_end_addr;
 extern int i386fbsd_sc_reg_offset[];