unsigned long insn;
int i;
- read_memory (pc, buf, sizeof (buf));
+ /* If we can't read the instruction at PC, return zero. */
+ if (target_read_memory (pc, buf, sizeof (buf)))
+ return 0;
insn = 0;
for (i = 0; i < sizeof (buf); i++)
insn = (insn << 8) | buf[i];
return insn;
}
+\f
+
+/* OpenBSD/sparc includes StackGhost, which according to the author's
+ website http://stackghost.cerias.purdue.edu "... transparently and
+ automatically protects applications' stack frames; more
+ specifically, it guards the return pointers. The protection
+ mechanisms require no application source or binary modification and
+ imposes only a negligible performance penalty."
+
+ The same website provides the following description of how
+ StackGhost works:
+
+ "StackGhost interfaces with the kernel trap handler that would
+ normally write out registers to the stack and the handler that
+ would read them back in. By XORing a cookie into the
+ return-address saved in the user stack when it is actually written
+ to the stack, and then XOR it out when the return-address is pulled
+ from the stack, StackGhost can cause attacker corrupted return
+ pointers to behave in a manner the attacker cannot predict.
+ StackGhost can also use several unused bits in the return pointer
+ to detect a smashed return pointer and abort the process."
+
+ For GDB this means that whenever we're reading %i7 from a stack
+ frame's window save area, we'll have to XOR the cookie.
+
+ More information on StackGuard can be found on in:
+
+ Mike Frantzen and Mike Shuey. "StackGhost: Hardware Facilitated
+ Stack Protection." 2001. Published in USENIX Security Symposium
+ '01. */
+
+/* Fetch StackGhost Per-Process XOR cookie. */
+
+ULONGEST
+sparc_fetch_wcookie (void)
+{
+ /* FIXME: kettenis/20040131: We should fetch the cookie from the
+ target. For now, return zero, which is right for targets without
+ StackGhost. */
+ return 0;
+}
+
\f
/* Return the contents if register REGNUM as an address. */
return;
}
+ /* Handle StackGhost. */
+ {
+ ULONGEST wcookie = sparc_fetch_wcookie ();
+
+ if (wcookie != 0 && !cache->frameless_p && regnum == SPARC_I7_REGNUM)
+ {
+ *optimizedp = 0;
+ *lvalp = not_lval;
+ *addrp = 0;
+ *realnump = -1;
+ if (valuep)
+ {
+ CORE_ADDR addr = cache->base + (regnum - SPARC_L0_REGNUM) * 4;
+ ULONGEST i6;
+
+ /* Read the value in from memory. */
+ i6 = get_frame_memory_unsigned (next_frame, addr, 4);
+ store_unsigned_integer (valuep, 4, i6 ^ wcookie);
+ }
+ return;
+ }
+ }
+
/* The previous frame's `local' and `in' registers have been saved
in the register save area. */
if (!cache->frameless_p
#if 0
/* NOTE: cagney/2004-01-17: For the moment disable this method. The
architecture and CORE-gdb will need new code (and a replacement for
- EXTRACT_STRUCT_VALUE_ADDRESS) before this can be made to work
- robustly. Here is a possible function signature: */
+ DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS) before this can be made to
+ work robustly. Here is a possible function signature: */
/* NOTE: cagney/2004-01-17: So far only the 32-bit SPARC ABI has been
identifed as having a way to robustly recover the address of a
struct-convention return-value (after the function has returned).
{
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
- if (strcmp (sect_name, ".reg") == 0 && sect_size == tdep->sizeof_gregset)
+ if (strcmp (sect_name, ".reg") == 0 && sect_size >= tdep->sizeof_gregset)
return tdep->gregset;
- if (strcmp (sect_name, ".reg2") == 0 && sect_size == tdep->sizeof_fpregset)
+ if (strcmp (sect_name, ".reg2") == 0 && sect_size >= tdep->sizeof_fpregset)
return tdep->fpregset;
return NULL;
tdep->pc_regnum = SPARC32_PC_REGNUM;
tdep->npc_regnum = SPARC32_NPC_REGNUM;
tdep->gregset = NULL;
- tdep->sizeof_gregset = 20 * 4;
+ tdep->sizeof_gregset = 0;
tdep->fpregset = NULL;
- tdep->sizeof_fpregset = 33 * 4;
+ tdep->sizeof_fpregset = 0;
tdep->plt_entry_size = 0;
set_gdbarch_long_double_bit (gdbarch, 128);
frame_unwind_append_sniffer (gdbarch, sparc32_frame_sniffer);
/* If we have register sets, enable the generic core file support. */
- if (tdep->gregset && tdep->fpregset)
+ if (tdep->gregset)
set_gdbarch_regset_from_core_section (gdbarch,
sparc_regset_from_core_section);
{
target_read_memory (sp + ((i - SPARC_L0_REGNUM) * 4),
buf + offset, 4);
+
+ /* Handle StackGhost. */
+ if (i == SPARC_I7_REGNUM)
+ {
+ ULONGEST wcookie = sparc_fetch_wcookie ();
+ ULONGEST i6 = extract_unsigned_integer (buf + offset, 4);
+
+ store_unsigned_integer (buf + offset, 4, i6 ^ wcookie);
+ }
+
regcache_raw_supply (regcache, i, buf);
}
}
if (regnum == -1 || regnum == SPARC_SP_REGNUM || regnum == i)
{
regcache_raw_collect (regcache, i, buf);
+
+ /* Handle StackGhost. */
+ if (i == SPARC_I7_REGNUM)
+ {
+ ULONGEST wcookie = sparc_fetch_wcookie ();
+ ULONGEST i6 = extract_unsigned_integer (buf + offset, 4);
+
+ store_unsigned_integer (buf + offset, 4, i6 ^ wcookie);
+ }
+
target_write_memory (sp + ((i - SPARC_L0_REGNUM) * 4),
buf + offset, 4);
}
projects / deliverable / binutils-gdb.git / blobdiff