[X86] Use ptrace(PTRACE_GETREGSET, NT_PRSTATUS) to get registers.

Unlike PTRACE_GETREGS, this new method detects 32-bit processes
reliably, without checking segment register values which
are undocumented and aren't part of any sort of API.
While at it, also fixed x32 detection to use __X32_SYSCALL_BIT,
as it should have been from the beginning.

* defs.h: Declare os_release and KERNEL_VERSION.
* strace.c: Make os_release non-static, remove KERNEL_VERSION define.
* syscall.c: New struct i386_user_regs_struct,
static union x86_regs_union and struct iovec x86_io.
(printcall): Use i386_regs or x86_64_regs depending on x86_io.iov_len.
(get_regs): On x86 and kernels 2.6.30+, use PTRACE_GETREGSET,
on earlier kernels fall back to old method.
(get_scno): [X86] Determine personality based on regset size
on scno & __X32_SYSCALL_BIT.
(syscall_fixup_on_sysenter): Use i386_regs or x86_64_regs depending
on x86_io.iov_len.
(get_syscall_args): Likewise.
(get_error): Likewise.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 1 insertions, 4 deletions

diff --git a/strace.c b/strace.c
index eac6ba59..bc98d365 100644
--- a/strace.c
+++ b/strace.c
@@ -58,9 +58,6 @@ extern char *optarg;
 # define my_tkill(tid, sig) kill((tid), (sig))
 #endif
 
-#undef KERNEL_VERSION
-#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
-
 cflag_t cflag = CFLAG_NONE;
 unsigned int followfork = 0;
 unsigned int ptrace_setoptions = 0;
@@ -146,7 +143,7 @@ static struct tcb **tcbtab;
 static unsigned int nprocs, tcbtabsize;
 static const char *progname;
 
-static unsigned os_release; /* generated from uname()'s u.release */
+unsigned os_release; /* generated from uname()'s u.release */
 
 static int detach(struct tcb *tcp);
 static int trace(void);