GDB's remote protocol requires M-profile cores to use the feature
name 'org.gnu.gdb.arm.m-profile' instead of the 'org.gnu.gdb.arm.core'
feature used for A- and R-profile cores. We weren't doing this, which
meant GDB treated our M-profile cores like A-profile ones. This mostly
doesn't matter, but for instance means that it doesn't correctly
handle backtraces where an M-profile exception frame is involved.
Ship a copy of GDB's arm-m-profile.xml and use it on the M-profile
cores. The integer registers have the same offsets as the
arm-core.xml, but register 25 is the M-profile XPSR rather than the
A-profile CPSR, so we need to update arm_cpu_gdb_read_register() and
arm_cpu_gdb_write_register() to handle XSPR reads and writes.
Fixes: https://bugs.launchpad.net/qemu/+bug/1877136
Signed-off-by: Peter Maydell <address@hidden>
---
configure | 4 ++--
target/arm/cpu.c | 1 +
target/arm/gdbstub.c | 22 ++++++++++++++++++----
gdb-xml/arm-m-profile.xml | 27 +++++++++++++++++++++++++++
4 files changed, 48 insertions(+), 6 deletions(-)
create mode 100644 gdb-xml/arm-m-profile.xml
diff --git a/configure b/configure
index 0d69c360c0e..360e7e6a0a4 100755
--- a/configure
+++ b/configure
@@ -7806,14 +7806,14 @@ case "$target_name" in
TARGET_SYSTBL_ABI=common,oabi
bflt="yes"
mttcg="yes"
- gdb_xml_files="arm-core.xml arm-vfp.xml arm-vfp3.xml arm-neon.xml"
+ gdb_xml_files="arm-core.xml arm-vfp.xml arm-vfp3.xml arm-neon.xml
arm-m-profile.xml"
;;
aarch64|aarch64_be)
TARGET_ARCH=aarch64
TARGET_BASE_ARCH=arm
bflt="yes"
mttcg="yes"
- gdb_xml_files="aarch64-core.xml aarch64-fpu.xml arm-core.xml arm-vfp.xml
arm-vfp3.xml arm-neon.xml"
+ gdb_xml_files="aarch64-core.xml aarch64-fpu.xml arm-core.xml arm-vfp.xml
arm-vfp3.xml arm-neon.xml arm-m-profile.xml"
;;
cris)
;;
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 5d64adfe76e..b386bbbfd12 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -2179,6 +2179,7 @@ static void arm_v7m_class_init(ObjectClass *oc, void
*data)
#endif
cc->cpu_exec_interrupt = arm_v7m_cpu_exec_interrupt;
+ cc->gdb_core_xml_file = "arm-m-profile.xml";
}
static const ARMCPRegInfo cortexr5_cp_reginfo[] = {
diff --git a/target/arm/gdbstub.c b/target/arm/gdbstub.c
index 063551df234..ecfa88f8e60 100644
--- a/target/arm/gdbstub.c
+++ b/target/arm/gdbstub.c
@@ -57,8 +57,12 @@ int arm_cpu_gdb_read_register(CPUState *cs, GByteArray
*mem_buf, int n)
}
return gdb_get_reg32(mem_buf, 0);
case 25:
- /* CPSR */
- return gdb_get_reg32(mem_buf, cpsr_read(env));
+ /* CPSR, or XPSR for M-profile */
+ if (arm_feature(env, ARM_FEATURE_M)) {
+ return gdb_get_reg32(mem_buf, xpsr_read(env));
+ } else {
+ return gdb_get_reg32(mem_buf, cpsr_read(env));
+ }
}
/* Unknown register. */
return 0;
@@ -98,8 +102,18 @@ int arm_cpu_gdb_write_register(CPUState *cs, uint8_t
*mem_buf, int n)
}
return 4;
case 25:
- /* CPSR */
- cpsr_write(env, tmp, 0xffffffff, CPSRWriteByGDBStub);
+ /* CPSR, or XPSR for M-profile */
+ if (arm_feature(env, ARM_FEATURE_M)) {
+ /*
+ * Don't allow writing to XPSR.Exception as it can cause
+ * a transition into or out of handler mode (it's not
+ * writeable via the MSR insn so this is a reasonable
+ * restriction). Other fields are safe to update.
+ */
+ xpsr_write(env, tmp, ~XPSR_EXCP);
+ } else {
+ cpsr_write(env, tmp, 0xffffffff, CPSRWriteByGDBStub);
+ }
return 4;
}
/* Unknown register. */
diff --git a/gdb-xml/arm-m-profile.xml b/gdb-xml/arm-m-profile.xml
new file mode 100644
index 00000000000..5319d764eeb
--- /dev/null
+++ b/gdb-xml/arm-m-profile.xml
@@ -0,0 +1,27 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2010-2020 Free Software Foundation, Inc.
+
+ Copying and distribution of this file, with or without modification,
+ are permitted in any medium without royalty provided the copyright
+ notice and this notice are preserved. -->
+
+<!DOCTYPE feature SYSTEM "gdb-target.dtd">
+<feature name="org.gnu.gdb.arm.m-profile">
+ <reg name="r0" bitsize="32"/>
+ <reg name="r1" bitsize="32"/>
+ <reg name="r2" bitsize="32"/>
+ <reg name="r3" bitsize="32"/>
+ <reg name="r4" bitsize="32"/>
+ <reg name="r5" bitsize="32"/>
+ <reg name="r6" bitsize="32"/>
+ <reg name="r7" bitsize="32"/>
+ <reg name="r8" bitsize="32"/>
+ <reg name="r9" bitsize="32"/>
+ <reg name="r10" bitsize="32"/>
+ <reg name="r11" bitsize="32"/>
+ <reg name="r12" bitsize="32"/>
+ <reg name="sp" bitsize="32" type="data_ptr"/>
+ <reg name="lr" bitsize="32"/>
+ <reg name="pc" bitsize="32" type="code_ptr"/>
+ <reg name="xpsr" bitsize="32" regnum="25"/>
+</feature>