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target/arm: Use correct GDB XML for M-profile cores

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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 <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20200507134755.13997-1-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2020-05-07 14:47:55 +01:00
parent 035b448b84
commit c888f7e0fd
4 changed files with 48 additions and 6 deletions
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4
configure vendored
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@ -7806,14 +7806,14 @@ case "$target_name" in
TARGET_SYSTBL_ABI=common,oabi TARGET_SYSTBL_ABI=common,oabi
bflt="yes" bflt="yes"
mttcg="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) aarch64|aarch64_be)
TARGET_ARCH=aarch64 TARGET_ARCH=aarch64
TARGET_BASE_ARCH=arm TARGET_BASE_ARCH=arm
bflt="yes" bflt="yes"
mttcg="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) cris)
;; ;;

27
gdb-xml/arm-m-profile.xml Normal file
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@ -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>

1
target/arm/cpu_tcg.c
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@ -605,6 +605,7 @@ static void arm_v7m_class_init(ObjectClass *oc, void *data)
#endif #endif
cc->cpu_exec_interrupt = arm_v7m_cpu_exec_interrupt; cc->cpu_exec_interrupt = arm_v7m_cpu_exec_interrupt;
cc->gdb_core_xml_file = "arm-m-profile.xml";
} }
static const ARMCPUInfo arm_tcg_cpus[] = { static const ARMCPUInfo arm_tcg_cpus[] = {

22
target/arm/gdbstub.c
View File

@ -57,8 +57,12 @@ int arm_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
} }
return gdb_get_reg32(mem_buf, 0); return gdb_get_reg32(mem_buf, 0);
case 25: case 25:
/* CPSR */ /* CPSR, or XPSR for M-profile */
return gdb_get_reg32(mem_buf, cpsr_read(env)); 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. */ /* Unknown register. */
return 0; return 0;
@ -98,8 +102,18 @@ int arm_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
} }
return 4; return 4;
case 25: case 25:
/* CPSR */ /* CPSR, or XPSR for M-profile */
cpsr_write(env, tmp, 0xffffffff, CPSRWriteByGDBStub); 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; return 4;
} }
/* Unknown register. */ /* Unknown register. */