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[Ping] [PATCH] Add support for accessing VFP registers to ARM native Linux
- From: Matthew Gretton-Dann <matthew dot gretton-dann at arm dot com>
- To: gdb-patches at sourceware dot org
- Date: Mon, 08 Mar 2010 09:54:21 +0000
- Subject: [Ping] [PATCH] Add support for accessing VFP registers to ARM native Linux
- References: <1267444251.6165.10.camel@e102111-lin.cambridge.arm.com>
Hi,
Has anybody had a chance to look at this patch which I submitted last
week yet? I am not concerned if it is just taking a while to review - I
just want to make sure it does not get missed by accident.
Thanks,
Matt
On Mon, 2010-03-01 at 11:50 +0000, Matthew Gretton-Dann wrote:
> All,
>
> The attached patch adds support for VFP registers to GDB running
> natively under ARM Linux. The patch is based in large part on the
> equivalent functionality in gdbserver for remote debugging of ARM Linux.
>
> I have tested it with arm-unknown-linux-gnueabi on a target with Neon,
> one with VFPv3-D16, one with VFPv2, and a target without VFP. I have
> also tested it on arm-none-linux on a target without VFP. The patch has
> not been tested on an XScale as I do not have access to an appropriate
> device.
>
> Can someone please review the patch, comment, and if appropriate commit
> it?
>
> Proposed ChangeLog:
>
> 2010-03-01 Matthew Gretton-Dann <matthew.gretton-dann@arm.com>
>
> * arm-tdep.h (gdb_regnum): Add ARM_FPSCR_REGNUM
> * arm-linux-nat.c (arm_linux_vfp_register_count): Add new
> variable.
> (fetch_vfp_registers): New function to fetch VFP registers.
> (store_vfp_registers): New function to store VFP registers.
> (arm_linux_fetch_inferior_registers): Add support for VFP
> registers.
> (arm_linux_store_inferior_registers): Likewise.
> (arm_linux_read_description): Likewise.
> (arm_read_auxv, arm_get_hwcap): New function.
> (_initialize_arm_linux_nat): Delay initialising iWMMX tdesc
> until we need it.
>
> Thanks,
>
> Matt
--
Matthew Gretton-Dann
Principal Engineer - Tools, PD Software
ARM Limited
Index: gdb/arm-linux-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/arm-linux-nat.c,v
retrieving revision 1.42
diff -u -p -r1.42 arm-linux-nat.c
--- gdb/arm-linux-nat.c 1 Jan 2010 07:31:29 -0000 1.42
+++ gdb/arm-linux-nat.c 1 Mar 2010 11:33:32 -0000
@@ -29,6 +29,7 @@
#include "arm-tdep.h"
#include "arm-linux-tdep.h"
+#include <elf/common.h>
#include <sys/user.h>
#include <sys/ptrace.h>
#include <sys/utsname.h>
@@ -41,6 +42,9 @@
#include "gdb_proc_service.h"
#include "features/arm-with-iwmmxt.c"
+#include "features/arm-with-vfpv2.c"
+#include "features/arm-with-vfpv3.c"
+#include "features/arm-with-neon.c"
#ifndef PTRACE_GET_THREAD_AREA
#define PTRACE_GET_THREAD_AREA 22
@@ -51,9 +55,25 @@
#define PTRACE_SETWMMXREGS 19
#endif
+#ifndef PTRACE_GETVFPREGS
+#define PTRACE_GETVFPREGS 27
+#define PTRACE_SETVFPREGS 28
+#endif
+
+/* These are in <asm/elf.h> in current kernels. */
+#define HWCAP_VFP 64
+#define HWCAP_IWMMXT 512
+#define HWCAP_NEON 4096
+#define HWCAP_VFPv3 8192
+#define HWCAP_VFPv3D16 16384
+
/* A flag for whether the WMMX registers are available. */
static int arm_linux_has_wmmx_registers;
+/* The number of 64-bit VFP registers we have (expect this to be 0, 16, or
+ 32). */
+static int arm_linux_vfp_register_count;
+
extern int arm_apcs_32;
/* The following variables are used to determine the version of the
@@ -447,6 +467,67 @@ store_wmmx_regs (const struct regcache *
}
}
+/* Fetch and store VFP Registers. The kernel object has space for 32
+ 64-bit registers, and the FPSCR. This is even when on a VFPv2 or
+ VFPv3D16 target. */
+#define VFP_REGS_SIZE (32 * 8 + 4)
+
+static void
+fetch_vfp_regs (struct regcache *regcache)
+{
+ char regbuf[VFP_REGS_SIZE];
+ int ret, regno, tid;
+
+ /* Get the thread id for the ptrace call. */
+ tid = GET_THREAD_ID (inferior_ptid);
+
+ ret = ptrace (PTRACE_GETVFPREGS, tid, 0, regbuf);
+ if (ret < 0)
+ {
+ warning (_("Unable to fetch VFPv3 registers."));
+ return;
+ }
+
+ for (regno = 0; regno < arm_linux_vfp_register_count; regno++)
+ regcache_raw_supply (regcache, regno + ARM_D0_REGNUM,
+ (char *) regbuf + regno * 8);
+
+ regcache_raw_supply (regcache, ARM_FPSCR_REGNUM,
+ (char *) regbuf + 32 * 8);
+}
+
+static void
+store_vfp_regs (const struct regcache *regcache)
+{
+ char regbuf[VFP_REGS_SIZE];
+ int ret, regno, tid;
+
+ /* Get the thread id for the ptrace call. */
+ tid = GET_THREAD_ID (inferior_ptid);
+
+ ret = ptrace (PTRACE_GETVFPREGS, tid, 0, regbuf);
+ if (ret < 0)
+ {
+ warning (_("Unable to fetch VFPv3 registers."));
+ return;
+ }
+
+ for (regno = 0; regno < arm_linux_vfp_register_count; regno++)
+ regcache_raw_collect (regcache, regno + ARM_D0_REGNUM,
+ (char *) regbuf + regno * 8);
+
+ regcache_raw_collect (regcache, ARM_FPSCR_REGNUM,
+ (char *) regbuf + 32 * 8);
+
+ ret = ptrace (PTRACE_SETVFPREGS, tid, 0, regbuf);
+
+ if (ret < 0)
+ {
+ warning (_("Unable to store VFPv3 registers."));
+ return;
+ }
+}
+
/* Fetch registers from the child process. Fetch all registers if
regno == -1, otherwise fetch all general registers or all floating
point registers depending upon the value of regno. */
@@ -461,6 +542,8 @@ arm_linux_fetch_inferior_registers (stru
fetch_fpregs (regcache);
if (arm_linux_has_wmmx_registers)
fetch_wmmx_regs (regcache);
+ if (arm_linux_vfp_register_count > 0)
+ fetch_vfp_regs (regcache);
}
else
{
@@ -471,6 +554,10 @@ arm_linux_fetch_inferior_registers (stru
else if (arm_linux_has_wmmx_registers
&& regno >= ARM_WR0_REGNUM && regno <= ARM_WCGR7_REGNUM)
fetch_wmmx_regs (regcache);
+ else if (arm_linux_vfp_register_count > 0
+ && regno >= ARM_D0_REGNUM
+ && regno <= ARM_D0_REGNUM + arm_linux_vfp_register_count)
+ fetch_vfp_regs (regcache);
}
}
@@ -488,6 +575,8 @@ arm_linux_store_inferior_registers (stru
store_fpregs (regcache);
if (arm_linux_has_wmmx_registers)
store_wmmx_regs (regcache);
+ if (arm_linux_vfp_register_count > 0)
+ store_vfp_regs (regcache);
}
else
{
@@ -498,6 +587,10 @@ arm_linux_store_inferior_registers (stru
else if (arm_linux_has_wmmx_registers
&& regno >= ARM_WR0_REGNUM && regno <= ARM_WCGR7_REGNUM)
store_wmmx_regs (regcache);
+ else if (arm_linux_vfp_register_count > 0
+ && regno >= ARM_D0_REGNUM
+ && regno <= ARM_D0_REGNUM + arm_linux_vfp_register_count)
+ store_vfp_regs (regcache);
}
}
@@ -575,23 +668,118 @@ get_linux_version (unsigned int *vmajor,
return ((*vmajor << 16) | (*vminor << 8) | *vrelease);
}
+/* Copy LEN bytes from inferior's auxiliary vector starting at OFFSET
+ to debugger memory starting at MYADDR. */
+
+static int
+arm_read_auxv(int offset, unsigned char *myaddr, unsigned int len)
+{
+ char filename[PATH_MAX];
+ int fd, n;
+ int pid = GET_LWP (inferior_ptid);
+
+ snprintf (filename, sizeof filename, "/proc/%d/auxv", pid);
+
+ fd = open (filename, O_RDONLY);
+ if (fd < 0)
+ return -1;
+
+ if (offset != (CORE_ADDR) 0
+ && lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset)
+ n = -1;
+ else
+ n = read (fd, myaddr, len);
+
+ close (fd);
+
+ return n;
+}
+
+static int
+arm_get_hwcap (unsigned long *valp)
+{
+ unsigned char *data = alloca (8);
+ int offset = 0;
+
+ while (arm_read_auxv (offset, data, 8) == 8)
+ {
+ unsigned int *data_p = (unsigned int *)data;
+ if (data_p[0] == AT_HWCAP)
+ {
+ *valp = data_p[1];
+ return 1;
+ }
+
+ offset += 8;
+ }
+
+ *valp = 0;
+ return 0;
+}
+
static const struct target_desc *
arm_linux_read_description (struct target_ops *ops)
{
- int ret;
- char regbuf[IWMMXT_REGS_SIZE];
+ unsigned long arm_hwcap = 0;
+ arm_linux_has_wmmx_registers = 0;
+ arm_linux_vfp_register_count = 0;
+
+ if (arm_get_hwcap (&arm_hwcap) == 0)
+ {
+ return NULL;
+ }
+
+ if (arm_hwcap & HWCAP_IWMMXT)
+ {
+ arm_linux_has_wmmx_registers = 1;
+ if (tdesc_arm_with_iwmmxt == NULL)
+ initialize_tdesc_arm_with_iwmmxt ();
+ return tdesc_arm_with_iwmmxt;
+ }
+
+ if (arm_hwcap & HWCAP_VFP)
+ {
+ int pid;
+ char *buf;
+ const struct target_desc * result = NULL;
+
+ /* NEON implies VFPv3-D32 or no-VFP unit. Say that we only support
+ Neon with VFPv3-D32. */
+ if (arm_hwcap & HWCAP_NEON)
+ {
+ arm_linux_vfp_register_count = 32;
+ if (tdesc_arm_with_neon == NULL)
+ initialize_tdesc_arm_with_neon ();
+ result = tdesc_arm_with_neon;
+ }
+ else if ((arm_hwcap & (HWCAP_VFPv3 | HWCAP_VFPv3D16)) == HWCAP_VFPv3)
+ {
+ arm_linux_vfp_register_count = 32;
+ if (tdesc_arm_with_vfpv3 == NULL)
+ initialize_tdesc_arm_with_vfpv3 ();
+ result = tdesc_arm_with_vfpv3;
+ }
+ else
+ {
+ arm_linux_vfp_register_count = 16;
+ if (tdesc_arm_with_vfpv2 == NULL)
+ initialize_tdesc_arm_with_vfpv2 ();
+ result = tdesc_arm_with_vfpv2;
+ }
+
+ /* Now make sure that the kernel supports reading these
+ registers. Support was added in 2.6.30. */
+ pid = GET_LWP (inferior_ptid);
+ errno = 0;
+ buf = alloca (VFP_REGS_SIZE);
+ if (ptrace (PTRACE_GETVFPREGS, pid, 0, buf) < 0
+ && errno == EIO)
+ result = NULL;
- ret = ptrace (PTRACE_GETWMMXREGS, GET_THREAD_ID (inferior_ptid),
- 0, regbuf);
- if (ret < 0)
- arm_linux_has_wmmx_registers = 0;
- else
- arm_linux_has_wmmx_registers = 1;
+ return result;
+ }
- if (arm_linux_has_wmmx_registers)
- return tdesc_arm_with_iwmmxt;
- else
- return NULL;
+ return NULL;
}
void _initialize_arm_linux_nat (void);
@@ -614,7 +802,4 @@ _initialize_arm_linux_nat (void)
/* Register the target. */
linux_nat_add_target (t);
-
- /* Initialize the standard target descriptions. */
- initialize_tdesc_arm_with_iwmmxt ();
}
Index: gdb/arm-tdep.h
===================================================================
RCS file: /cvs/src/src/gdb/arm-tdep.h,v
retrieving revision 1.39
diff -u -p -r1.39 arm-tdep.h
--- gdb/arm-tdep.h 1 Feb 2010 16:13:15 -0000 1.39
+++ gdb/arm-tdep.h 1 Mar 2010 11:33:32 -0000
@@ -50,6 +50,7 @@ enum gdb_regnum {
ARM_WCGR7_REGNUM = ARM_WCGR0_REGNUM + 7,
ARM_D0_REGNUM, /* VFP double-precision registers. */
ARM_D31_REGNUM = ARM_D0_REGNUM + 31,
+ ARM_FPSCR_REGNUM,
ARM_NUM_REGS,