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[86.156.236.171]) by smtp.gmail.com with ESMTPSA id v5sm12779919wrn.71.2018.11.28.14.49.55 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 28 Nov 2018 14:49:55 -0800 (PST) From: Andrew Burgess To: gdb-patches@sourceware.org Cc: jimw@sifive.com, palmer@sifive.com, jhb@FreeBSD.org, Andrew Burgess Subject: [RFC] gdb/riscv: Add read_description method for riscv_linux_nat_target Date: Wed, 28 Nov 2018 22:49:53 +0000 Message-Id: <20181128224953.22441-1-andrew.burgess@embecosm.com> X-IsSubscribed: yes Adds riscv_linux_nat_target::read_description method to find a suitable target description for the native linux target we are running on. Currently this will supply a suitably sized set of x-registers, and will probe the kernel to see if the f-registers are readable. If they are readable then we currently assume that the f-registers are the same size as the x-registers as I don't know of a good way to probe the f-register length. This will obviously need fixing in future. As of Linux 4.19 there is no ptrace support for reading the f-registers, this should appear in 4.20, so right now we only return target descriptions without f-registers. gdb/ChangeLog: * riscv-linux-nat.c: Add 'inferior.h' and 'target-descriptions.h' header files. (riscv_linux_nat_target::read_description): New method. --- gdb/ChangeLog | 6 ++++++ gdb/riscv-linux-nat.c | 38 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 44 insertions(+) diff --git a/gdb/riscv-linux-nat.c b/gdb/riscv-linux-nat.c index d51f6e30218..f0705bc763f 100644 --- a/gdb/riscv-linux-nat.c +++ b/gdb/riscv-linux-nat.c @@ -21,6 +21,8 @@ #include "gregset.h" #include "linux-nat.h" #include "riscv-tdep.h" +#include "inferior.h" +#include "target-descriptions.h" #include "elf/common.h" @@ -34,6 +36,9 @@ public: /* Add our register access methods. */ void fetch_registers (struct regcache *regcache, int regnum) override; void store_registers (struct regcache *regcache, int regnum) override; + + /* Read suitable target description. */ + const struct target_desc *read_description () override; }; static riscv_linux_nat_target the_riscv_linux_nat_target; @@ -155,6 +160,39 @@ fill_fpregset (const struct regcache *regcache, prfpregset_t *fpregs, regcache->raw_collect (RISCV_CSR_FCSR_REGNUM, &fpregs->__d.__fcsr); } +/* Return a target description for the current target. */ + +const struct target_desc * +riscv_linux_nat_target::read_description () +{ + struct riscv_gdbarch_features features; + struct iovec iov; + elf_fpregset_t regs; + int tid; + + /* Figuring out xlen is easy. */ + features.xlen = sizeof (elf_greg_t); + + tid = inferior_ptid.lwp (); + + iov.iov_base = ®s; + iov.iov_len = sizeof (regs); + + /* Can we fetch the f-registers? */ + if (ptrace (PTRACE_GETREGSET, tid, NT_FPREGSET, + (PTRACE_TYPE_ARG3) &iov) == -1) + features.flen = 0; /* No f-registers. */ + else + { + /* TODO: We need a way to figure out the actual length of the + f-registers. We could have 64-bit x-registers, with 32-bit + f-registers. For now, just assumed xlen and flen match. */ + features.flen = features.xlen; + } + + return riscv_create_target_description (features); +} + /* Fetch REGNUM (or all registers if REGNUM == -1) from the target into REGCACHE using PTRACE_GETREGSET. */