From 6cdd651fda1315cb43a6a50223350da0da3f6dcf Mon Sep 17 00:00:00 2001 From: Luis Machado Date: Mon, 18 Nov 2019 16:36:53 -0300 Subject: [PATCH] Improve target description check for SVE in gdbserver The current code checks for the presence of a SVE target description by comparing the number of registers. This is a bit fragile since the number of registers can change whenever we add new sets. Like PAC, for example. If the comparison breaks, then we're left with SVE registers in the description, but gdbserver doesn't send the registers to GDB, which in turn displays stale information to the user. The following patch changes the check to use the SVE feature string instead, which hopefully should be more stable. gdb/gdbserver/ChangeLog: 2019-11-20 Luis Machado * linux-aarch64-low.c (is_sve_tdesc): Check against target feature instead of register count. * tdesc.c (tdesc_contains_feature): New function. * tdesc.h (tdesc_contains_feature): New prototype. Change-Id: I28b782cb1677560ca9a06a1be442974b25aabae4 --- gdb/gdbserver/ChangeLog | 7 +++++++ gdb/gdbserver/linux-aarch64-low.c | 2 +- gdb/gdbserver/tdesc.c | 16 ++++++++++++++++ gdb/gdbserver/tdesc.h | 5 +++++ 4 files changed, 29 insertions(+), 1 deletion(-) diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog index fde6abbecb3..a5da6b584de 100644 --- a/gdb/gdbserver/ChangeLog +++ b/gdb/gdbserver/ChangeLog @@ -1,3 +1,10 @@ +2019-11-20 Luis Machado + + * linux-aarch64-low.c (is_sve_tdesc): Check against target feature + instead of register count. + * tdesc.c (tdesc_contains_feature): New function. + * tdesc.h (tdesc_contains_feature): New prototype. + 2019-11-15 Christian Biesinger * Makefile.in: Add safe-strerror.c. diff --git a/gdb/gdbserver/linux-aarch64-low.c b/gdb/gdbserver/linux-aarch64-low.c index 87a21a0e774..9e234e0578b 100644 --- a/gdb/gdbserver/linux-aarch64-low.c +++ b/gdb/gdbserver/linux-aarch64-low.c @@ -83,7 +83,7 @@ is_sve_tdesc (void) { struct regcache *regcache = get_thread_regcache (current_thread, 0); - return regcache->tdesc->reg_defs.size () == AARCH64_SVE_NUM_REGS; + return tdesc_contains_feature (regcache->tdesc, "org.gnu.gdb.aarch64.sve"); } static void diff --git a/gdb/gdbserver/tdesc.c b/gdb/gdbserver/tdesc.c index 92a0a6005f3..817e69a58f2 100644 --- a/gdb/gdbserver/tdesc.c +++ b/gdb/gdbserver/tdesc.c @@ -186,3 +186,19 @@ tdesc_create_feature (struct target_desc *tdesc, const char *name) tdesc->features.emplace_back (new_feature); return new_feature; } + +/* See gdbsupport/tdesc.h. */ + +bool +tdesc_contains_feature (const target_desc *tdesc, const std::string &feature) +{ + gdb_assert (tdesc != nullptr); + + for (const tdesc_feature_up &f : tdesc->features) + { + if (f->name == feature) + return true; + } + + return false; +} diff --git a/gdb/gdbserver/tdesc.h b/gdb/gdbserver/tdesc.h index b93f53c8d44..da21cdaad47 100644 --- a/gdb/gdbserver/tdesc.h +++ b/gdb/gdbserver/tdesc.h @@ -93,4 +93,9 @@ void init_target_desc (struct target_desc *tdesc, const struct target_desc *current_target_desc (void); +/* Return true if TDESC contains the feature described by string FEATURE. + Return false otherwise. */ +bool tdesc_contains_feature (const target_desc *tdesc, + const std::string &feature); + #endif /* GDBSERVER_TDESC_H */ -- 2.30.2