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Determine target description for native aarch64

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I find the following test fail when I test native aarch64 gdb with
arm program,

(gdb) PASS: gdb.base/attach-pie-noexec.exp: attach
set architecture arm^M
warning: Selected architecture arm is not compatible with reported target architecture aarch64^M
Architecture `arm' not recognized.^M
The target architecture is set automatically (currently aarch64)^M
(gdb) FAIL: gdb.base/attach-pie-noexec.exp: set architecture arm

GDB thinks the target is aarch64, but it isn't.  Nowadays, we are
using some entries AT_PHENT and AT_HWCAP in auxv to determine whether
the process is a 32-bit arm one or 64-bit aarch64 one, and get the
right gdbarch.  However, in the process of parsing auxv (in
inf_ptrace_auxv_parse), the size of int and data pointer of
target_gdbarch is used.  If debug program exists (in most of cases),
target_gdbarch is already set according to the debug program, which
is arm in my case.  Then, GDB can parse auxv successfully.  However,
in gdb.base/attach-pie-noexec.exp, the debug program is removed,
target_gdbarch is aarch64 when GDB parse auxv, so GDB can't parse
it successfully.

Instead of using auxv, we check the return value of ptrace NT_ARM_VFP.
If the program is an arm process, NT_ARM_VFP is OK, otherwise, error
is returned.

Additionally, we only return tdesc_arm_with_neon for arm process,
because neon is mandatory on ARMv8.

gdb:

2016-08-04  Yao Qi  <yao.qi@linaro.org>

	* aarch64-linux-nat.c (tdesc_arm_with_vfpv3): Remove the
	declaration.
	(aarch64_linux_read_description): Remove code on getting
	auxv and select target description on it.  Select target
	description by the result of NT_ARM_VFP ptrace request.
This commit is contained in:
Yao Qi 2016-08-04 11:37:57 +01:00
parent fcd4a73d7d
commit 6f67973b42
2 changed files with 19 additions and 39 deletions
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8
gdb/ChangeLog
View file

@ -1,3 +1,11 @@
2016-08-04 Yao Qi <yao.qi@linaro.org>
* aarch64-linux-nat.c (tdesc_arm_with_vfpv3): Remove the
declaration.
(aarch64_linux_read_description): Remove code on getting
auxv and select target description on it. Select target
description by the result of NT_ARM_VFP ptrace request.
2016-08-03 Tom Tromey <tom@tromey.com>
PR python/18565:

50
gdb/aarch64-linux-nat.c
View file

@ -481,7 +481,6 @@ aarch64_linux_child_post_startup_inferior (struct target_ops *self,
super_post_startup_inferior (self, ptid);
}
extern struct target_desc *tdesc_arm_with_vfpv3;
extern struct target_desc *tdesc_arm_with_neon;
/* Implement the "to_read_description" target_ops method. */
@ -489,47 +488,20 @@ extern struct target_desc *tdesc_arm_with_neon;
static const struct target_desc *
aarch64_linux_read_description (struct target_ops *ops)
{
CORE_ADDR at_phent;
int ret, tid;
gdb_byte regbuf[VFP_REGS_SIZE];
struct iovec iovec;
if (target_auxv_search (ops, AT_PHENT, &at_phent) == 1)
{
if (at_phent == sizeof (Elf64_External_Phdr))
return tdesc_aarch64;
else
{
CORE_ADDR arm_hwcap = 0;
tid = ptid_get_lwp (inferior_ptid);
if (target_auxv_search (ops, AT_HWCAP, &arm_hwcap) != 1)
return ops->beneath->to_read_description (ops->beneath);
iovec.iov_base = regbuf;
iovec.iov_len = VFP_REGS_SIZE;
#ifndef COMPAT_HWCAP_VFP
#define COMPAT_HWCAP_VFP (1 << 6)
#endif
#ifndef COMPAT_HWCAP_NEON
#define COMPAT_HWCAP_NEON (1 << 12)
#endif
#ifndef COMPAT_HWCAP_VFPv3
#define COMPAT_HWCAP_VFPv3 (1 << 13)
#endif
if (arm_hwcap & COMPAT_HWCAP_VFP)
{
char *buf;
const struct target_desc *result = NULL;
if (arm_hwcap & COMPAT_HWCAP_NEON)
result = tdesc_arm_with_neon;
else if (arm_hwcap & COMPAT_HWCAP_VFPv3)
result = tdesc_arm_with_vfpv3;
return result;
}
return NULL;
}
}
return tdesc_aarch64;
ret = ptrace (PTRACE_GETREGSET, tid, NT_ARM_VFP, &iovec);
if (ret == 0)
return tdesc_arm_with_neon;
else
return tdesc_aarch64;
}
/* Convert a native/host siginfo object, into/from the siginfo in the