[COMMIT] frv-linux-tdep.c: Adjust an RT signal related constant

Kevin Buettner
2005-03-18T20:28:39Z

I've just committed that patch below. Thanks to Richard Sandiford for
finding the problem and suggesting the fix. (This patch looks bigger
than it really is; it only touches one line of executable code. The
rest of the changes are updates to comments.)

* frv-linux-tdep.c (frv_linux_sigcontext_reg_addr): Update comments.
Adjust incorrectly computed constant for realtime signal frame.

Index: frv-linux-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/frv-linux-tdep.c,v
retrieving revision 1.5
diff -u -p -r1.5 frv-linux-tdep.c
--- frv-linux-tdep.c 11 Feb 2005 18:13:49 -0000 1.5
+++ frv-linux-tdep.c 18 Mar 2005 20:20:38 -0000
@@ -67,14 +67,14 @@ frv_linux_pc_in_sigtramp (CORE_ADDR pc,
return retval;
}

-/* Given NEXT_FRAME, "callee" frame of the sigtramp frame that we
+/* Given NEXT_FRAME, the "callee" frame of the sigtramp frame that we
wish to decode, and REGNO, one of the frv register numbers defined
in frv-tdep.h, return the address of the saved register (corresponding
to REGNO) in the sigtramp frame. Return -1 if the register is not
found in the sigtramp frame. The magic numbers in the code below
were computed by examining the following kernel structs:

- From arch/frvnommu/signal.c:
+ From arch/frv/kernel/signal.c:

struct sigframe
{
@@ -96,7 +96,7 @@ frv_linux_pc_in_sigtramp (CORE_ADDR pc,
uint32_t retcode[2];
};

- From include/asm-frvnommu/ucontext.h:
+ From include/asm-frv/ucontext.h:

struct ucontext {
unsigned long uc_flags;
@@ -106,14 +106,22 @@ frv_linux_pc_in_sigtramp (CORE_ADDR pc,
sigset_t uc_sigmask;
};

- From include/asm-frvnommu/sigcontext.h:
+ From include/asm-frv/signal.h:
+
+ typedef struct sigaltstack {
+ void *ss_sp;
+ int ss_flags;
+ size_t ss_size;
+ } stack_t;
+
+ From include/asm-frv/sigcontext.h:

struct sigcontext {
struct user_context sc_context;
unsigned long sc_oldmask;
} __attribute__((aligned(8)));

- From include/asm-frvnommu/registers.h:
+ From include/asm-frv/registers.h:
struct user_int_regs
{
unsigned long psr;
@@ -184,15 +192,19 @@ frv_linux_sigcontext_reg_addr (struct fr
else if (tramp_type == RT_SIGTRAMP)
{
/* For a realtime sigtramp frame, SP + 12 contains a pointer
- to the a ucontext struct. The ucontext struct contains
- a sigcontext struct starting 12 bytes in. */
+ to the a ucontext struct. The ucontext struct contains a
+ sigcontext struct starting 24 bytes in. (The offset of
+ uc_mcontext within struct ucontext is derived as follows:
+ stack_t is a 12-byte struct and struct sigcontext is
+ 8-byte aligned. This gives an offset of 8 + 12 + 4 (for
+ padding) = 24.) */
if (target_read_memory (sp + 12, buf, sizeof buf) != 0)
{
warning (_("Can't read realtime sigtramp frame."));
return 0;
}
sc_addr = extract_unsigned_integer (buf, sizeof buf);
- sc_addr += 12;
+ sc_addr += 24;
}
else
internal_error (__FILE__, __LINE__, _("not a signal trampoline"));