[PATCH 7/9] Support TLS variables on FreeBSD/i386.

John Baldwin
2019-01-22T18:43:49Z

Derive the pointer to the DTV array from the gs_base register. As
with FreeBSD/amd64, gs_base is currently only available via the native
target.

gdb/ChangeLog:

* i386-fbsd-tdep.c (i386fbsd_get_thread_local_address): New.
(i386fbsd_init_abi): Install gdbarch
"fetch_tls_load_module_address" and "get_thread_local_address"
methods.
---
gdb/ChangeLog | 7 +++++++
gdb/i386-fbsd-tdep.c | 29 +++++++++++++++++++++++++++++
2 files changed, 36 insertions(+)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 7e97fae997..06c637c80a 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2019-01-22 John Baldwin <jhb@FreeBSD.org>
+
+ * i386-fbsd-tdep.c (i386fbsd_get_thread_local_address): New.
+ (i386fbsd_init_abi): Install gdbarch
+ "fetch_tls_load_module_address" and "get_thread_local_address"
+ methods.
+
2019-01-22 John Baldwin <jhb@FreeBSD.org>

* amd64-fbsd-tdep.c (amd64fbsd_get_thread_local_address): New.
diff --git a/gdb/i386-fbsd-tdep.c b/gdb/i386-fbsd-tdep.c
index 239ca91abe..01141b9e14 100644
--- a/gdb/i386-fbsd-tdep.c
+++ b/gdb/i386-fbsd-tdep.c
@@ -320,6 +320,30 @@ i386fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
"XSAVE extended state", cb_data);
}

+/* Implement the get_thread_local_address gdbarch method. */
+
+static CORE_ADDR
+i386fbsd_get_thread_local_address (struct gdbarch *gdbarch, ptid_t ptid,
+ CORE_ADDR lm_addr, CORE_ADDR offset)
+{
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+ struct regcache *regcache;
+
+ if (tdep->fsbase_regnum == -1)
+ error (_("Unable to fetch %%gsbase"));
+
+ regcache = get_thread_arch_regcache (ptid, gdbarch);
+
+ target_fetch_registers (regcache, tdep->fsbase_regnum + 1);
+
+ ULONGEST gsbase;
+ if (regcache->cooked_read (tdep->fsbase_regnum + 1, &gsbase) != REG_VALID)
+ error (_("Unable to fetch %%gsbase"));
+
+ CORE_ADDR dtv_addr = gsbase + gdbarch_ptr_bit (gdbarch) / 8;
+ return fbsd_get_thread_local_address (gdbarch, dtv_addr, lm_addr, offset);
+}
+
static void
i386fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
@@ -418,6 +442,11 @@ i386fbsd4_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)

set_gdbarch_core_read_description (gdbarch,
i386fbsd_core_read_description);
+
+ set_gdbarch_fetch_tls_load_module_address (gdbarch,
+ svr4_fetch_objfile_link_map);
+ set_gdbarch_get_thread_local_address (gdbarch,
+ i386fbsd_get_thread_local_address);
}

void
--
2.19.2