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Re: [PATCH, FT32] Proper support for address <-> pointer conversions
- From: Yao Qi <qiyaoltc at gmail dot com>
- To: James Bowman <james dot bowman at ftdichip dot com>
- Cc: "gdb-patches\ at sourceware dot org" <gdb-patches at sourceware dot org>
- Date: Tue, 22 Sep 2015 17:36:18 +0100
- Subject: Re: [PATCH, FT32] Proper support for address <-> pointer conversions
- Authentication-results: sourceware.org; auth=none
- References: <CA9BBF0458F83C4F9051448B941B57D119614F72 at glaexch1>
James Bowman <james.bowman@ftdichip.com> writes:
> FT32 is a Harvard architecture with two address spaces -- RAM and flash.
> This patch properly implements the address to pointer conversion method,
> and its reverse. There are some other small fixes to handle address
> spaces.
Hi James,
Thanks for your patch. A few comments below...
Please split your patch, in order to place each independent small fix in
one patch.
>
> OK to apply?
>
> 2015-09-21 James Bowman <james.bowman@ftdichip.com>
>
> * ft32-tdep.c: Properly support address <-> pointer conversions,
> so that FT32's address spaces (RAM and flash) work correctly
> when dereferencing pointers in gdb.
> * ft32-tdep.h: Add a type for an address space 1 pointer.
The changelog entry looks incorrect to me. Please read
https://sourceware.org/gdb/wiki/ContributionChecklist
>
>
> diff --git a/gdb/ft32-tdep.c b/gdb/ft32-tdep.c
> index 2e5deca..d6e8c6d 100644
> --- a/gdb/ft32-tdep.c
> +++ b/gdb/ft32-tdep.c
> @@ -117,7 +117,7 @@ static struct type *
> ft32_register_type (struct gdbarch *gdbarch, int reg_nr)
> {
> if (reg_nr == FT32_PC_REGNUM)
> - return builtin_type (gdbarch)->builtin_func_ptr;
> + return gdbarch_tdep (gdbarch)->pc_type;
> else if (reg_nr == FT32_SP_REGNUM || reg_nr == FT32_FP_REGNUM)
> return builtin_type (gdbarch)->builtin_data_ptr;
> else
> @@ -270,6 +270,88 @@ ft32_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
> return pc;
> }
>
> +/* Convert from address to pointer and vice-versa. */
> +
> +static void
> +ft32_address_to_pointer (struct gdbarch *gdbarch,
> + struct type *type, gdb_byte *buf, CORE_ADDR addr)
> +{
> + enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
> +
> + store_unsigned_integer (buf, TYPE_LENGTH (type), byte_order,
> + addr);
> +}
ft32_address_to_pointer is exactly the same as
unsigned_address_to_pointer, which is the default implementation of
gdbarch method address_to_pointer. IOW, we don't need this function.
> +
> +static CORE_ADDR
> +ft32_pointer_to_address (struct gdbarch *gdbarch,
> + struct type *type, const gdb_byte *buf)
We need comments to this function, like,
"Implementation of ....."
> +{
> + enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
> + CORE_ADDR addr
> + = extract_unsigned_integer (buf, TYPE_LENGTH (type), byte_order);
A blank line is needed here.
> + if (TYPE_ADDRESS_CLASS_1 (type))
> + return addr;
> + else
> + return addr | RAM_BIAS;
> +}
> +
> +static CORE_ADDR
> +ft32_integer_to_address (struct gdbarch *gdbarch,
> + struct type *type, const gdb_byte *buf)
> +{
> + ULONGEST addr = unpack_long (type, buf);
> +
> + return addr;
> +}
> +
Do we really need this function? Looks it makes no differences after
this hook is installed to gdbarch.
>
> static CORE_ADDR
> @@ -498,6 +580,15 @@ ft32_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
> tdep = XNEW (struct gdbarch_tdep);
> gdbarch = gdbarch_alloc (&info, tdep);
>
> + /* Create a type for PC. We can't use builtin types here, as they may not
> + be defined. */
> + tdep->void_type = arch_type (gdbarch, TYPE_CODE_VOID, 1, "void");
> + tdep->func_void_type = make_function_type (tdep->void_type, NULL);
> + tdep->pc_type = arch_type (gdbarch, TYPE_CODE_PTR, 4, NULL);
> + TYPE_TARGET_TYPE (tdep->pc_type) = tdep->func_void_type;
> + TYPE_UNSIGNED (tdep->pc_type) = 1;
> + TYPE_INSTANCE_FLAGS (tdep->pc_type) |= TYPE_INSTANCE_FLAG_ADDRESS_CLASS_1;
> +
> set_gdbarch_read_pc (gdbarch, ft32_read_pc);
> set_gdbarch_write_pc (gdbarch, ft32_write_pc);
> set_gdbarch_unwind_sp (gdbarch, ft32_unwind_sp);
> @@ -510,6 +601,10 @@ ft32_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
>
> set_gdbarch_return_value (gdbarch, ft32_return_value);
>
> + set_gdbarch_address_to_pointer (gdbarch, ft32_address_to_pointer);
> + set_gdbarch_pointer_to_address (gdbarch, ft32_pointer_to_address);
> + set_gdbarch_integer_to_address (gdbarch, ft32_integer_to_address);
> +
> set_gdbarch_skip_prologue (gdbarch, ft32_skip_prologue);
> set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
> set_gdbarch_breakpoint_from_pc (gdbarch, ft32_breakpoint_from_pc);
> @@ -535,6 +630,12 @@ ft32_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
> /* Support simple overlay manager. */
> set_gdbarch_overlay_update (gdbarch, simple_overlay_update);
>
> + set_gdbarch_address_class_type_flags (gdbarch, ft32_address_class_type_flags);
> + set_gdbarch_address_class_name_to_type_flags
> + (gdbarch, ft32_address_class_name_to_type_flags);
> + set_gdbarch_address_class_type_flags_to_name
> + (gdbarch, ft32_address_class_type_flags_to_name);
> +
> return gdbarch;
> }
>
> diff --git a/gdb/ft32-tdep.h b/gdb/ft32-tdep.h
> index 5c52480..f236163 100644
> --- a/gdb/ft32-tdep.h
> +++ b/gdb/ft32-tdep.h
> @@ -22,7 +22,12 @@
>
> struct gdbarch_tdep
> {
> - /* gdbarch target dependent data here. Currently unused for FT32. */
> + /* Type for void. */
> + struct type *void_type;
> + /* Type for a function returning void. */
> + struct type *func_void_type;
> + /* Type for a pointer to a function. Used for the type of PC. */
> + struct type *pc_type;
Only pc_type is used (in ft32_register_type), so we don't need to add
fields void_type and func_void_type.
--
Yao (éå)