From: Thiago Jung Bauermann via Gdb-patches <gdb-patches@sourceware.org>
To: gdb-patches@sourceware.org
Subject: [PATCH v2 1/2] gdb/aarch64: Fix thread's gdbarch when SVE vector length changes
Date: Fri, 5 Aug 2022 00:46:47 +0000 [thread overview]
Message-ID: <20220805004648.111358-2-thiago.bauermann@linaro.org> (raw)
In-Reply-To: <20220805004648.111358-1-thiago.bauermann@linaro.org>
When the inferior program changes the SVE length, GDB can stop tracking
some registers as it obtains the new gdbarch that corresponds to the
updated length:
Breakpoint 1, do_sve_ioctl_test () at sve-ioctls.c:44
44 res = prctl(PR_SVE_SET_VL, i, 0, 0, 0, 0);
(gdb) print i
$2 = 32
(gdb) info registers
⋮
[ snip registers x0 to x30 ]
⋮
sp 0xffffffffeff0 0xffffffffeff0
pc 0xaaaaaaaaa8ac 0xaaaaaaaaa8ac <do_sve_ioctl_test+112>
cpsr 0x60000000 [ EL=0 BTYPE=0 C Z ]
fpsr 0x0 0
fpcr 0x0 0
vg 0x8 8
tpidr 0xfffff7fcb320 0xfffff7fcb320
(gdb) next
45 if (res < 0) {
(gdb) info registers
⋮
[ snip registers x0 to x30 ]
⋮
sp 0xffffffffeff0 0xffffffffeff0
pc 0xaaaaaaaaa8cc 0xaaaaaaaaa8cc <do_sve_ioctl_test+144>
cpsr 0x200000 [ EL=0 BTYPE=0 SS ]
fpsr 0x0 0
fpcr 0x0 0
vg 0x4 4
(gdb)
Notice that register tpidr disappeared when vg (which holds the vector
length) changed from 8 to 4. The tpidr register is provided by the
org.gnu.gdb.aarch64.tls feature.
This happens because the code that searches for a new gdbarch to match the
new vector length in aarch64_linux_nat_target::thread_architecture doesn't
take into account the features present in the target description associated
with the previous gdbarch. This patch makes it do that.
Since the id member of struct gdbarch_info is now unused, it's removed.
---
gdb/aarch64-linux-nat.c | 11 ++++++++---
gdb/aarch64-tdep.c | 41 ++++++++++++++++++++++++-----------------
gdb/aarch64-tdep.h | 2 ++
gdb/gdbarch.h | 13 ++-----------
4 files changed, 36 insertions(+), 31 deletions(-)
diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
index a457fcd48ad8..eda79ec6d35c 100644
--- a/gdb/aarch64-linux-nat.c
+++ b/gdb/aarch64-linux-nat.c
@@ -900,11 +900,16 @@ aarch64_linux_nat_target::thread_architecture (ptid_t ptid)
/* We reach here if the vector length for the thread is different from its
value at process start. Lookup gdbarch via info (potentially creating a
- new one), stashing the vector length inside id. Use -1 for when SVE
- unavailable, to distinguish from an unset value of 0. */
+ new one) by using a target description that corresponds to the new vq value
+ and the current architecture features. */
+
+ const struct target_desc *tdesc = gdbarch_target_desc (inf->gdbarch);
+ aarch64_features features = aarch64_features_from_target_desc (tdesc);
+ features.vq = vq;
+
struct gdbarch_info info;
info.bfd_arch_info = bfd_lookup_arch (bfd_arch_aarch64, bfd_mach_aarch64);
- info.id = (int *) (vq == 0 ? -1 : vq);
+ info.target_desc = aarch64_read_description (features);
return gdbarch_find_by_info (info);
}
diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c
index 8670197a8889..c9ce4f95447c 100644
--- a/gdb/aarch64-tdep.c
+++ b/gdb/aarch64-tdep.c
@@ -3372,6 +3372,27 @@ aarch64_get_tdesc_vq (const struct target_desc *tdesc)
return sve_vq_from_vl (vl);
}
+/* Get the AArch64 features present in the given target description. */
+
+aarch64_features
+aarch64_features_from_target_desc (const struct target_desc *tdesc)
+{
+ aarch64_features features;
+
+ if (tdesc == nullptr)
+ return features;
+
+ features.vq = aarch64_get_tdesc_vq (tdesc);
+ features.pauth
+ = (tdesc_find_feature (tdesc, "org.gnu.gdb.aarch64.pauth") != nullptr);
+ features.mte
+ = (tdesc_find_feature (tdesc, "org.gnu.gdb.aarch64.mte") != nullptr);
+ features.tls
+ = (tdesc_find_feature (tdesc, "org.gnu.gdb.aarch64.tls") != nullptr);
+
+ return features;
+}
+
/* Implement the "cannot_store_register" gdbarch method. */
static int
@@ -3422,17 +3443,7 @@ aarch64_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
int i, num_regs = 0, num_pseudo_regs = 0;
int first_pauth_regnum = -1, ra_sign_state_offset = -1;
int first_mte_regnum = -1, tls_regnum = -1;
-
- /* Use the vector length passed via the target info. Here -1 is used for no
- SVE, and 0 is unset. If unset then use the vector length from the existing
- tdesc. */
- uint64_t vq = 0;
- if (info.id == (int *) -1)
- vq = 0;
- else if (info.id != 0)
- vq = (uint64_t) info.id;
- else
- vq = aarch64_get_tdesc_vq (info.target_desc);
+ uint64_t vq = aarch64_get_tdesc_vq (info.target_desc);
if (vq > AARCH64_MAX_SVE_VQ)
internal_error (__FILE__, __LINE__, _("VQ out of bounds: %s (max %d)"),
@@ -3452,12 +3463,8 @@ aarch64_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
/* Ensure we always have a target descriptor, and that it is for the given VQ
value. */
const struct target_desc *tdesc = info.target_desc;
- if (!tdesc_has_registers (tdesc) || vq != aarch64_get_tdesc_vq (tdesc))
- {
- aarch64_features features;
- features.vq = vq;
- tdesc = aarch64_read_description (features);
- }
+ if (!tdesc_has_registers (tdesc))
+ tdesc = aarch64_read_description ({});
gdb_assert (tdesc);
feature_core = tdesc_find_feature (tdesc,"org.gnu.gdb.aarch64.core");
diff --git a/gdb/aarch64-tdep.h b/gdb/aarch64-tdep.h
index 5bdd733dce32..d8513023c376 100644
--- a/gdb/aarch64-tdep.h
+++ b/gdb/aarch64-tdep.h
@@ -121,6 +121,8 @@ struct aarch64_gdbarch_tdep : gdbarch_tdep_base
};
const target_desc *aarch64_read_description (const aarch64_features &features);
+aarch64_features
+aarch64_features_from_target_desc (const struct target_desc *tdesc);
extern int aarch64_process_record (struct gdbarch *gdbarch,
struct regcache *regcache, CORE_ADDR addr);
diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h
index 324958469a7e..1287f0214885 100644
--- a/gdb/gdbarch.h
+++ b/gdb/gdbarch.h
@@ -250,17 +250,8 @@ struct gdbarch_info
bfd *abfd = nullptr;
- union
- {
- /* Architecture-specific target description data. Numerous targets
- need only this, so give them an easy way to hold it. */
- struct tdesc_arch_data *tdesc_data;
-
- /* SPU file system ID. This is a single integer, so using the
- generic form would only complicate code. Other targets may
- reuse this member if suitable. */
- int *id;
- };
+ /* Architecture-specific target description data. */
+ struct tdesc_arch_data *tdesc_data;
enum gdb_osabi osabi = GDB_OSABI_UNKNOWN;
next prev parent reply other threads:[~2022-08-05 0:47 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-05 0:46 [PATCH v2 0/2] Fix bug in aarch64-linux GDB when inferior changes SVE vector length Thiago Jung Bauermann via Gdb-patches
2022-08-05 0:46 ` Thiago Jung Bauermann via Gdb-patches [this message]
2022-08-05 17:26 ` [PATCH v2 1/2] gdb/aarch64: Fix thread's gdbarch when SVE vector length changes Luis Machado via Gdb-patches
2022-08-05 0:46 ` [PATCH v2 2/2] gdb/testsuite: Add test for AArch64 Scalable Vector Extension Thiago Jung Bauermann via Gdb-patches
2022-08-05 17:23 ` Luis Machado via Gdb-patches
2022-08-05 21:57 ` Thiago Jung Bauermann via Gdb-patches
2022-08-17 20:46 ` Thiago Jung Bauermann via Gdb-patches
2022-08-18 8:56 ` Luis Machado via Gdb-patches
2022-08-18 11:37 ` Thiago Jung Bauermann via Gdb-patches
2022-08-18 13:47 ` Luis Machado via Gdb-patches
2022-08-18 14:08 ` Thiago Jung Bauermann via Gdb-patches
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