It's worth noting that the vector CSR predicate() has a similar
run-time check logic to the FPU CSR. With the previous patch our
gdbstub can correctly report these vector CSRs via the CSR xml.
Commit 719d3561b2 ("target/riscv: gdb: support vector registers for rv64 & rv32")
inserted these vector CSRs in an ad-hoc, non-standard way in the
riscv-vector.xml. Now we can treat these CSRs no different from
other CSRs.
Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Message-ID: <20230228104035.1879882-13-bmeng@tinylab.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Since commit 94452ac4cf ("target/riscv: remove fflags, frm, and fcsr from riscv-*-fpu.xml")
the 3 FPU CSRs are removed from the XML target decription. The
original intent of that commit was based on the assumption that
the 3 FPU CSRs will show up in the riscv-csr.xml so the ones in
riscv-*-fpu.xml are redundant. But unforuantely that is not true.
As the FPU CSR predicate() has a run-time check on MSTATUS.FS,
at the time when CSR XML is generated MSTATUS.FS is unset, hence
no FPU CSRs will be reported.
The FPU CSR predicate() already considered such a case of being
accessed by a debugger. All we need to do is to turn on debugger
mode before calling predicate().
Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Message-ID: <20230228104035.1879882-12-bmeng@tinylab.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The gdbstub CSR XML is dynamically generated according to the result
of the CSR predicate() result. This has been working fine until
commit 7100fe6c24 ("target/riscv: Enable privileged spec version 1.12")
introduced the privilege spec version check in riscv_csrrw_check().
When debugging the 'sifive_u' machine whose priv spec is at 1.10,
gdbstub reports priv spec 1.12 CSRs like menvcfg in the XML, hence
we see "remote failure reply 'E14'" message when examining all CSRs
via "info register system" from gdb.
Add the priv spec version check in the CSR XML generation logic to
fix this issue.
Fixes: 7100fe6c24 ("target/riscv: Enable privileged spec version 1.12")
Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Message-ID: <20230228104035.1879882-2-bmeng@tinylab.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
While testing some changes to GDB's handling for the RISC-V registers
fcsr, fflags, and frm, I spotted that QEMU includes these registers
twice in the target description it sends to GDB, once in the fpu
feature, and once in the csr feature.
Right now things basically work OK, QEMU maps these registers onto two
different register numbers, e.g. fcsr maps to both 68 and 73, and GDB
can use either of these to access the register.
However, GDB's target descriptions don't really work this way, each
register should appear just once in a target description, mapping the
register name onto the number GDB should use when accessing the
register on the target. Duplicate register names actually result in
duplicate registers on the GDB side, however, as the registers have
the same name, the user can only access one of these registers.
Currently GDB has a hack in place, specifically for RISC-V, to spot
the duplicate copies of these three registers, and hide them from the
user, ensuring the user only ever sees a single copy of each.
In this commit I propose fixing this issue on the QEMU side, and in
the process, simplify the fpu register handling a little.
I think we should, remove fflags, frm, and fcsr from the two (32-bit
and 64-bit) fpu feature xml files. These files will only contain the
32 core floating point register f0 to f31. The fflags, frm, and fcsr
registers will continue to be advertised in the csr feature as they
currently are.
With that change made, I will simplify riscv_gdb_get_fpu and
riscv_gdb_set_fpu, removing the extra handling for the 3 status
registers.
Signed-off-by: Andrew Burgess <aburgess@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <0fbf2a5b12e3210ff3867d5cf7022b3f3462c9c8.1661934573.git.aburgess@redhat.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
At present QEMU RISC-V uses a hardcoded XML to report the feature
"org.gnu.gdb.riscv.csr" [1]. There are two major issues with the
approach being used currently:
- The XML does not specify the "regnum" field of a CSR entry, hence
consecutive numbers are used by the remote GDB client to access
CSRs. In QEMU we have to maintain a map table to convert the GDB
number to the hardware number which is error prone.
- The XML contains some CSRs that QEMU does not implement at all,
which causes an "E14" response sent to remote GDB client.
Change to generate the CSR register list dynamically, based on the
availability presented in the CSR function table. This new approach
will reflect a correct list of CSRs that QEMU actually implements.
[1] https://sourceware.org/gdb/current/onlinedocs/gdb/RISC_002dV-Features.html#RISC_002dV-Features
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210116054123.5457-2-bmeng.cn@gmail.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Add the Hypervisor CSRs to CPUState and at the same time (to avoid
bisect issues) update the CSR macros for the v0.5 Hyp spec.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
The size of the FPU registers is dictated by the 'f' and 'd' features,
not the core processor register size. Processors with the 'd' feature
have 64-bit FPU registers. Processors without the 'd' feature but with
the 'f' feature have 32-bit FPU registers.
Signed-off-by: Keith Packard <keithp@keithp.com>
[Palmer: This requires manually triggering a rebuild of
riscv32-softmmu/gdbstub-xml.c]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Currently only PRV_U, PRV_S and PRV_M are supported, so this patch ensures that
the privilege mode is set to one of them. Once support for the H-extension is
added, this code will also need to properly update the virtualization status
when switching between VU/VS-modes and M-mode.
Signed-off-by: Jonathan Behrens <jonathan@fintelia.io>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This patch enables a debugger to read the current privilege level via a virtual
"priv" register. When compiled with CONFIG_USER_ONLY the register is still
visible but always reports the value zero.
Signed-off-by: Jonathan Behrens <jonathan@fintelia.io>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
If the number of registers reported to the gdbstub code does not match the
number in the associated XML file, then the register numbers used by the stub
may get out of sync with a remote GDB instance.
Signed-off-by: Jonathan Behrens <jonathan@fintelia.io>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
While debugging an application with GDB the following might happen:
(gdb) return
Make xxx return now? (y or n) y
Could not fetch register "fflags"; remote failure reply 'E14'
This is because riscv_gdb_get_fpu calls riscv_csrrw_debug with a wrong csr
number (8). It should use the csr_register_map in order to reach the
riscv_cpu_get_fflags callback.
Signed-off-by: KONRAD Frederic <frederic.konrad@adacore.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
No header includes qemu-common.h after this commit, as prescribed by
qemu-common.h's file comment.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190523143508.25387-5-armbru@redhat.com>
[Rebased with conflicts resolved automatically, except for
include/hw/arm/xlnx-zynqmp.h hw/arm/nrf51_soc.c hw/arm/msf2-soc.c
block/qcow2-refcount.c block/qcow2-cluster.c block/qcow2-cache.c
target/arm/cpu.h target/lm32/cpu.h target/m68k/cpu.h target/mips/cpu.h
target/moxie/cpu.h target/nios2/cpu.h target/openrisc/cpu.h
target/riscv/cpu.h target/tilegx/cpu.h target/tricore/cpu.h
target/unicore32/cpu.h target/xtensa/cpu.h; bsd-user/main.c and
net/tap-bsd.c fixed up]
The gdb CSR xml file has registers in documentation order, not numerical
order, so we need a table to map the register numbers. This also adds
fairly standard gdb hooks to access xml specified registers.
notice:
The fpu xml from gdb 8.3 has unused register #, 65 and make first
csr register # become 69. We register extra register on gdb to correct
csr offset calculation
Signed-off-by: Jim Wilson <jimw@sifive.com>
Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Previous CSR code uses csr_read_helper and csr_write_helper
to update CSR registers however this interface prevents
atomic read/modify/write CSR operations; in addition
there is no trap-free method to access to CSRs due
to the monolithic CSR functions call longjmp.
The current iCSR interface is not safe to be called by
target/riscv/gdbstub.c as privilege checks or missing CSRs
may call longjmp to generate exceptions. It needs to
indicate existence so traps can be generated in the
CSR instruction helpers.
This commit moves CSR access from the monolithic switch
statements in target/riscv/op_helper.c into modular
read/write functions in target/riscv/csr.c using a new
function pointer table for dispatch (which can later
be used to allow CPUs to hook up model specific CSRs).
A read/modify/write interface is added to support atomic
CSR operations and a non-trapping interface is added
to allow exception-free access to CSRs by the debugger.
The CSR functions and CSR dispatch table are ordered
to match The RISC-V Instruction Set Manual, Volume II:
Privileged Architecture Version 1.10, 2.2 CSR Listing.
An API is added to allow derived cpu instances to modify
or implement new CSR operations.
Signed-off-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
