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[PATCH] hurd: Add enough auxv support for AT_ENTRY for PIE binaries
- From: Samuel Thibault <samuel dot thibault at ens-lyon dot org>
- To: gdb-patches at sourceware dot org
- Cc: Samuel Thibault <samuel dot thibault at ens-lyon dot org>
- Date: Wed, 27 Dec 2017 16:41:56 +0100
- Subject: [PATCH] hurd: Add enough auxv support for AT_ENTRY for PIE binaries
- Authentication-results: sourceware.org; auth=none
gdb/ChangeLog:
* gdb/gnu-nat.c: Include <elf.h> and <link.h>.
(gnu_xfer_auxv): New function.
(gnu_xfer_partial): Call gnu_xfer_auxv when `object' is
TARGET_OBJECT_AUXV.
---
gdb/ChangeLog | 7 +++++++
gdb/gnu-nat.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 65 insertions(+)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 4d85029b99..40d8e6e1cf 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2017-12-22 Samuel Thibault <samuel.thibault@ens-lyon.org>
+
+ * gdb/gnu-nat.c: Include <elf.h> and <link.h>.
+ (gnu_xfer_auxv): New function.
+ (gnu_xfer_partial): Call gnu_xfer_auxv when `object' is
+ TARGET_OBJECT_AUXV.
+
2017-12-27 Franck Jullien <franck.jullien@gmail.com>
Stafford Horne <shorne@gmail.com>
diff --git a/gdb/gnu-nat.c b/gdb/gnu-nat.c
index 0d500ea38d..7d9c7d8dfa 100644
--- a/gdb/gnu-nat.c
+++ b/gdb/gnu-nat.c
@@ -52,6 +52,8 @@ extern "C"
#include <setjmp.h>
#include <signal.h>
#include <sys/ptrace.h>
+#include <elf.h>
+#include <link.h>
#include "inferior.h"
#include "symtab.h"
@@ -2541,6 +2543,60 @@ gnu_xfer_memory (gdb_byte *readbuf, const gdb_byte *writebuf,
}
}
+/* GNU does not have auxv, but we can at least fake the AT_ENTRY entry for PIE
+ binaries. */
+static enum target_xfer_status
+gnu_xfer_auxv (gdb_byte *readbuf, const gdb_byte *writebuf,
+ CORE_ADDR memaddr, ULONGEST len, ULONGEST *xfered_len)
+{
+ task_t task = (gnu_current_inf
+ ? (gnu_current_inf->task
+ ? gnu_current_inf->task->port : 0)
+ : 0);
+ process_t proc;
+ int res;
+ kern_return_t err;
+ vm_address_t entry;
+ ElfW(auxv_t) auxv[2];
+
+ if (task == MACH_PORT_NULL)
+ return TARGET_XFER_E_IO;
+ if (writebuf != NULL)
+ return TARGET_XFER_E_IO;
+
+ if (memaddr == sizeof (auxv))
+ return TARGET_XFER_EOF;
+ if (memaddr > sizeof (auxv))
+ return TARGET_XFER_E_IO;
+
+ err = proc_task2proc (proc_server, task, &proc);
+ if (err != 0)
+ return TARGET_XFER_E_IO;
+
+ /* Get entry from proc server. */
+ err = proc_get_entry (proc, &entry);
+ if (err != 0)
+ return TARGET_XFER_E_IO;
+
+ /* Fake auxv entry. */
+ auxv[0].a_type = AT_ENTRY;
+ auxv[0].a_un.a_val = entry;
+ auxv[1].a_type = AT_NULL;
+ auxv[1].a_un.a_val = 0;
+
+ inf_debug (gnu_current_inf, "reading auxv %s[%s] --> %s",
+ paddress (target_gdbarch (), memaddr), pulongest (len),
+ host_address_to_string (readbuf));
+
+ if (memaddr + len > sizeof (auxv))
+ len = sizeof (auxv) - memaddr;
+
+ memcpy (readbuf, (gdb_byte *) &auxv + memaddr, len);
+ *xfered_len = len;
+
+ return TARGET_XFER_OK;
+}
+
/* Target to_xfer_partial implementation. */
static enum target_xfer_status
@@ -2553,6 +2609,8 @@ gnu_xfer_partial (struct target_ops *ops, enum target_object object,
{
case TARGET_OBJECT_MEMORY:
return gnu_xfer_memory (readbuf, writebuf, offset, len, xfered_len);
+ case TARGET_OBJECT_AUXV:
+ return gnu_xfer_auxv (readbuf, writebuf, offset, len, xfered_len);
default:
return TARGET_XFER_E_IO;
}
--
2.11.0