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[binutils-gdb] gdb/riscv: Add read_description method for riscv_linux_nat_target
- From: Andrew Burgess <aburgess at sourceware dot org>
- To: gdb-cvs at sourceware dot org
- Date: 30 Nov 2018 18:22:25 -0000
- Subject: [binutils-gdb] gdb/riscv: Add read_description method for riscv_linux_nat_target
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=92528b6772a19dd671b52d954c14886b11fc0a8d
commit 92528b6772a19dd671b52d954c14886b11fc0a8d
Author: Andrew Burgess <andrew.burgess@embecosm.com>
Date: Wed Nov 28 22:42:27 2018 +0000
gdb/riscv: Add read_description method for riscv_linux_nat_target
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.
Diff:
---
gdb/ChangeLog | 6 ++++++
gdb/riscv-linux-nat.c | 38 ++++++++++++++++++++++++++++++++++++++
2 files changed, 44 insertions(+)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 666f078..96cab87 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
2018-11-30 Andrew Burgess <andrew.burgess@embecosm.com>
+ * riscv-linux-nat.c: Add 'inferior.h' and 'target-descriptions.h'
+ header files.
+ (riscv_linux_nat_target::read_description): New method.
+
+2018-11-30 Andrew Burgess <andrew.burgess@embecosm.com>
+
* arch/riscv.h (riscv_gdbarch_features::hash): New method.
* arch/riscv.c (struct riscv_gdbarch_features_hasher): New.
(riscv_tdesc_cache): New global.
diff --git a/gdb/riscv-linux-nat.c b/gdb/riscv-linux-nat.c
index d51f6e3..f0705bc 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. */