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Re: [PATCH] Fix interrupt.exp fails with m32 in x86_64


On 04/22/14 02:27, Mark Kettenis wrote:
Date: Tue, 22 Apr 2014 00:16:53 +0800
From: Hui Zhu<hui_zhu@mentor.com>

I make a patch that let eax sign-extend in function
amd64_collect_native_gregset
that can handle this issue.
It can handle the issue and pass the regression test.
Please help me review it.
I don't think the generic amd64 target code is the proper place to
work around Linux kernel bugs.  If you really want to work around this
bug in GDB, it should probably be done in the Linux-specific
i386/amd64 native code.

Mark

Hi Mark,

Thanks for your review.
I will keep work on the patch for Linux kernel to Linux can handle it.
But I worried about even if this issue is fixed in Linux kernel.
A lot of GDB will still work with the old Linux kernel. So I make this patch.

I make a new patch the move %eax sign-extend code to amd64-linux-nat.c.

Thanks,
Hui

2014-04-22  Hui Zhu <hui@codesourcery.com>

    * amd64-linux-nat.c (fill_gregset): Make %eax
    sign-extended.
    (amd64_linux_store_inferior_registers): Change
    amd64_collect_native_gregset to fill_gregset.
    * amd64-nat.c (amd64_native_gregset_reg_offset): Remove static.
    * amd64-nat.h (amd64_native_gregset_reg_offset): Add extern.

--- a/gdb/amd64-linux-nat.c
+++ b/gdb/amd64-linux-nat.c
@@ -126,7 +126,27 @@ void
 fill_gregset (const struct regcache *regcache,
           elf_gregset_t *gregsetp, int regnum)
 {
+  struct gdbarch *gdbarch = get_regcache_arch (regcache);
+
   amd64_collect_native_gregset (regcache, gregsetp, regnum);
+
+  if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32
+      && (regnum == I386_EAX_REGNUM || regnum == -1))
+    {
+      /* Make %eax get sign-extended to 64 bits.  */
+      LONGEST val;
+      char *regs = (char *) gregsetp;
+      int offset = amd64_native_gregset_reg_offset (gdbarch,
+                            I386_EAX_REGNUM);
+
+      regcache_raw_collect (regcache, I386_EAX_REGNUM,
+                regs + offset);
+      val = extract_signed_integer ((gdb_byte *)(regs + offset),
+                    4,
+                    gdbarch_byte_order (gdbarch));
+      store_signed_integer ((gdb_byte *)(regs + offset), 8,
+                gdbarch_byte_order (gdbarch), val);
+    }
 }

/* Transfering floating-point registers between GDB, inferiors and cores. */
@@ -232,7 +252,7 @@ amd64_linux_store_inferior_registers (st
       if (ptrace (PTRACE_GETREGS, tid, 0, (long) &regs) < 0)
     perror_with_name (_("Couldn't get registers"));

-      amd64_collect_native_gregset (regcache, &regs, regnum);
+      fill_gregset (regcache, &regs, regnum);

       if (ptrace (PTRACE_SETREGS, tid, 0, (long) &regs) < 0)
     perror_with_name (_("Couldn't write registers"));
--- a/gdb/amd64-nat.c
+++ b/gdb/amd64-nat.c
@@ -51,7 +51,7 @@ int amd64_native_gregset64_num_regs = AM
 /* Return the offset of REGNUM within the appropriate native
    general-purpose register set.  */

-static int
+int
 amd64_native_gregset_reg_offset (struct gdbarch *gdbarch, int regnum)
 {
   int *reg_offset = amd64_native_gregset64_reg_offset;
--- a/gdb/amd64-nat.h
+++ b/gdb/amd64-nat.h
@@ -30,6 +30,12 @@ extern int amd64_native_gregset32_num_re
 extern int *amd64_native_gregset64_reg_offset;
 extern int amd64_native_gregset64_num_regs;

+/* Return the offset of REGNUM within the appropriate native
+   general-purpose register set.  */
+
+extern int amd64_native_gregset_reg_offset (struct gdbarch *gdbarch,
+                        int regnum);
+
 /* Return whether the native general-purpose register set supplies
    register REGNUM.  */



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