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[binutils-gdb] Avoid setting or recording negative alignments when the target stores multiple octets in a single by
- From: Nick Clifton <nickc at sourceware dot org>
- To: bfd-cvs at sourceware dot org
- Date: 18 Feb 2016 09:49:22 -0000
- Subject: [binutils-gdb] Avoid setting or recording negative alignments when the target stores multiple octets in a single by
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=9136aa49abcb3f23171e01ebd16ee03cc1032943
commit 9136aa49abcb3f23171e01ebd16ee03cc1032943
Author: Dan Gisselquist <dgisselq@verizon.net>
Date: Thu Feb 18 09:47:31 2016 +0000
Avoid setting or recording negative alignments when the target stores multiple octets in a single byte.
gas * read.c (finish_bundle): Avoid recording a negative alignment.
(do_align): Use unsigned values for n, len and max. Only create
a frag if the alignment requirement is greater than the minimum
byte alignment. Avoid recording a negative alignment.
(s_align): Use unsigned values where appropriate.
(bss_alloc): Use an unsigned value for the alignment.
(sizeof_sleb128): Add a comment noting that we encode one octet
per byte, regardless of the value of OCTETS_PER_BYTE_POWER.
(emit_leb129_expr): Abort if the emitted encoding was longer than
expected.
* read.h (output_leb128): Update prototype.
(sizeof_leb128): Update prototype.
(bss_alloc): Update prototype.
* write.c (record_alignment): Use an unsigned value for the
alignment. Do not record alignments less than the minimum
alignment for a byte.
* write.h (record_alignment): Update prototype.
Diff:
---
gas/ChangeLog | 21 ++++++
gas/read.c | 220 +++++++++++++++++++++++++++++++++-------------------------
gas/read.h | 10 +--
gas/write.c | 7 +-
gas/write.h | 6 +-
5 files changed, 160 insertions(+), 104 deletions(-)
diff --git a/gas/ChangeLog b/gas/ChangeLog
index 3688728..7236c3e 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,24 @@
+2016-02-18 Dan Gisselquist <dgisselq@verizon.net>
+ Nick Clifton <nickc@redhat.com>
+
+ * read.c (finish_bundle): Avoid recording a negative alignment.
+ (do_align): Use unsigned values for n, len and max. Only create
+ a frag if the alignment requirement is greater than the minimum
+ byte alignment. Avoid recording a negative alignment.
+ (s_align): Use unsigned values where appropriate.
+ (bss_alloc): Use an unsigned value for the alignment.
+ (sizeof_sleb128): Add a comment noting that we encode one octet
+ per byte, regardless of the value of OCTETS_PER_BYTE_POWER.
+ (emit_leb129_expr): Abort if the emitted encoding was longer than
+ expected.
+ * read.h (output_leb128): Update prototype.
+ (sizeof_leb128): Update prototype.
+ (bss_alloc): Update prototype.
+ * write.c (record_alignment): Use an unsigned value for the
+ alignment. Do not record alignments less than the minimum
+ alignment for a byte.
+ * write.h (record_alignment): Update prototype.
+
2016-02-17 Max Filippov <jcmvbkbc@gmail.com>
* config/tc-xtensa.c (xtensa_move_literals): Fix check for
diff --git a/gas/read.c b/gas/read.c
index 5c04789..f8fff78 100644
--- a/gas/read.c
+++ b/gas/read.c
@@ -238,7 +238,6 @@ static unsigned int bundle_lock_depth;
#endif
static void do_s_func (int end_p, const char *default_prefix);
-static void do_align (int, char *, int, int);
static void s_align (int, int);
static void s_altmacro (int);
static void s_bad_end (int);
@@ -487,6 +486,7 @@ static offsetT
get_absolute_expr (expressionS *exp)
{
expression_and_evaluate (exp);
+
if (exp->X_op != O_constant)
{
if (exp->X_op != O_absent)
@@ -685,7 +685,8 @@ finish_bundle (fragS *frag, unsigned int size)
/* We do this every time rather than just in s_bundle_align_mode
so that we catch any affected section without needing hooks all
over for all paths that do section changes. It's cheap enough. */
- record_alignment (now_seg, bundle_align_p2 - OCTETS_PER_BYTE_POWER);
+ if (bundle_align_p2 > OCTETS_PER_BYTE_POWER)
+ record_alignment (now_seg, bundle_align_p2 - OCTETS_PER_BYTE_POWER);
}
/* Assemble one instruction. This takes care of the bundle features
@@ -736,6 +737,75 @@ single instruction is %u bytes long but .bundle_align_mode limit is %u"),
#endif /* HANDLE_BUNDLE */
+static bfd_boolean
+in_bss (void)
+{
+ flagword flags = bfd_get_section_flags (stdoutput, now_seg);
+
+ return (flags & SEC_ALLOC) && !(flags & (SEC_LOAD | SEC_HAS_CONTENTS));
+}
+
+/* Guts of .align directive:
+ N is the power of two to which to align. A value of zero is accepted but
+ ignored: the default alignment of the section will be at least this.
+ FILL may be NULL, or it may point to the bytes of the fill pattern.
+ LEN is the length of whatever FILL points to, if anything. If LEN is zero
+ but FILL is not NULL then LEN is treated as if it were one.
+ MAX is the maximum number of characters to skip when doing the alignment,
+ or 0 if there is no maximum. */
+
+static void
+do_align (unsigned int n, char *fill, unsigned int len, unsigned int max)
+{
+ if (now_seg == absolute_section || in_bss ())
+ {
+ if (fill != NULL)
+ while (len-- > 0)
+ if (*fill++ != '\0')
+ {
+ if (now_seg == absolute_section)
+ as_warn (_("ignoring fill value in absolute section"));
+ else
+ as_warn (_("ignoring fill value in section `%s'"),
+ segment_name (now_seg));
+ break;
+ }
+ fill = NULL;
+ len = 0;
+ }
+
+#ifdef md_flush_pending_output
+ md_flush_pending_output ();
+#endif
+
+#ifdef md_do_align
+ md_do_align (n, fill, len, max, just_record_alignment);
+#endif
+
+ /* Only make a frag if we HAVE to... */
+ if ((n > OCTETS_PER_BYTE_POWER) && !need_pass_2)
+ {
+ if (fill == NULL)
+ {
+ if (subseg_text_p (now_seg))
+ frag_align_code (n, max);
+ else
+ frag_align (n, 0, max);
+ }
+ else if (len <= 1)
+ frag_align (n, *fill, max);
+ else
+ frag_align_pattern (n, fill, len, max);
+ }
+
+#ifdef md_do_align
+ just_record_alignment: ATTRIBUTE_UNUSED_LABEL
+#endif
+
+ if (n > OCTETS_PER_BYTE_POWER)
+ record_alignment (now_seg, n - OCTETS_PER_BYTE_POWER);
+}
+
/* We read the file, putting things into a web that represents what we
have been reading. */
void
@@ -1337,14 +1407,6 @@ convert_to_bignum (expressionS *exp, int sign)
exp->X_add_number = i;
}
-static bfd_boolean
-in_bss (void)
-{
- flagword flags = bfd_get_section_flags (stdoutput, now_seg);
-
- return (flags & SEC_ALLOC) && !(flags & (SEC_LOAD | SEC_HAS_CONTENTS));
-}
-
/* For most MRI pseudo-ops, the line actually ends at the first
nonquoted space. This function looks for that point, stuffs a null
in, and sets *STOPCP to the character that used to be there, and
@@ -1401,62 +1463,6 @@ s_abort (int ignore ATTRIBUTE_UNUSED)
as_fatal (_(".abort detected. Abandoning ship."));
}
-/* Guts of .align directive. N is the power of two to which to align.
- FILL may be NULL, or it may point to the bytes of the fill pattern.
- LEN is the length of whatever FILL points to, if anything. MAX is
- the maximum number of characters to skip when doing the alignment,
- or 0 if there is no maximum. */
-
-static void
-do_align (int n, char *fill, int len, int max)
-{
- if (now_seg == absolute_section || in_bss ())
- {
- if (fill != NULL)
- while (len-- > 0)
- if (*fill++ != '\0')
- {
- if (now_seg == absolute_section)
- as_warn (_("ignoring fill value in absolute section"));
- else
- as_warn (_("ignoring fill value in section `%s'"),
- segment_name (now_seg));
- break;
- }
- fill = NULL;
- len = 0;
- }
-
-#ifdef md_flush_pending_output
- md_flush_pending_output ();
-#endif
-#ifdef md_do_align
- md_do_align (n, fill, len, max, just_record_alignment);
-#endif
-
- /* Only make a frag if we HAVE to... */
- if (n != 0 && !need_pass_2)
- {
- if (fill == NULL)
- {
- if (subseg_text_p (now_seg))
- frag_align_code (n, max);
- else
- frag_align (n, 0, max);
- }
- else if (len <= 1)
- frag_align (n, *fill, max);
- else
- frag_align_pattern (n, fill, len, max);
- }
-
-#ifdef md_do_align
- just_record_alignment: ATTRIBUTE_UNUSED_LABEL
-#endif
-
- record_alignment (now_seg, n - OCTETS_PER_BYTE_POWER);
-}
-
/* Handle the .align pseudo-op. A positive ARG is a default alignment
(in bytes). A negative ARG is the negative of the length of the
fill pattern. BYTES_P is non-zero if the alignment value should be
@@ -1466,14 +1472,14 @@ do_align (int n, char *fill, int len, int max)
#endif
static void
-s_align (int arg, int bytes_p)
+s_align (signed int arg, int bytes_p)
{
unsigned int align_limit = TC_ALIGN_LIMIT;
unsigned int align;
char *stop = NULL;
char stopc = 0;
offsetT fill = 0;
- int max;
+ unsigned int max;
int fill_p;
if (flag_mri)
@@ -1553,15 +1559,16 @@ s_align (int arg, int bytes_p)
}
else
{
- int fill_len;
+ unsigned int fill_len;
if (arg >= 0)
fill_len = 1;
else
fill_len = -arg;
+
if (fill_len <= 1)
{
- char fill_char;
+ char fill_char = 0;
fill_char = fill;
do_align (align, &fill_char, fill_len, max);
@@ -1571,7 +1578,12 @@ s_align (int arg, int bytes_p)
char ab[16];
if ((size_t) fill_len > sizeof ab)
- abort ();
+ {
+ as_warn (_("fill pattern too long, truncating to %u"),
+ (unsigned) sizeof ab);
+ fill_len = sizeof ab;
+ }
+
md_number_to_chars (ab, fill, fill_len);
do_align (align, ab, fill_len, max);
}
@@ -2429,7 +2441,7 @@ s_linkonce (int ignore ATTRIBUTE_UNUSED)
}
void
-bss_alloc (symbolS *symbolP, addressT size, int align)
+bss_alloc (symbolS *symbolP, addressT size, unsigned int align)
{
char *pfrag;
segT current_seg = now_seg;
@@ -2453,7 +2465,7 @@ bss_alloc (symbolS *symbolP, addressT size, int align)
#endif
subseg_set (bss_seg, 1);
- if (align)
+ if (align > OCTETS_PER_BYTE_POWER)
{
record_alignment (bss_seg, align);
frag_align (align, 0, 0);
@@ -2907,7 +2919,7 @@ s_mri_sect (char *type ATTRIBUTE_UNUSED)
if (c == ',')
{
- int align;
+ unsigned int align;
++input_line_pointer;
align = get_absolute_expression ();
@@ -3006,7 +3018,7 @@ s_mri_sect (char *type ATTRIBUTE_UNUSED)
}
else if (strcasecmp (seccmd, "align") == 0)
{
- int align;
+ unsigned int align;
(void) restore_line_pointer (c);
align = get_absolute_expression ();
@@ -4993,9 +5005,25 @@ float_cons (/* Clobbers input_line-pointer, checks end-of-line. */
demand_empty_rest_of_line ();
}
-/* Return the size of a LEB128 value. */
+/* LEB128 Encoding.
-static inline int
+ Note - we are using the DWARF standard's definition of LEB128 encoding
+ where each 7-bit value is a stored in a byte, *not* an octet. This
+ means that on targets where a byte contains multiple octets there is
+ a *huge waste of space*. (This also means that we do not have to
+ have special versions of these functions for when OCTETS_PER_BYTE_POWER
+ is non-zero).
+
+ If the 7-bit values were to be packed into N-bit bytes (where N > 8)
+ we would then have to consider whether multiple, successive LEB128
+ values should be packed into the bytes without padding (bad idea) or
+ whether each LEB128 number is padded out to a whole number of bytes.
+ Plus you have to decide on the endianness of packing octets into a
+ byte. */
+
+/* Return the size of a LEB128 value in bytes. */
+
+static inline unsigned int
sizeof_sleb128 (offsetT value)
{
int size = 0;
@@ -5016,7 +5044,7 @@ sizeof_sleb128 (offsetT value)
return size;
}
-static inline int
+static inline unsigned int
sizeof_uleb128 (valueT value)
{
int size = 0;
@@ -5031,7 +5059,7 @@ sizeof_uleb128 (valueT value)
return size;
}
-int
+unsigned int
sizeof_leb128 (valueT value, int sign)
{
if (sign)
@@ -5040,9 +5068,9 @@ sizeof_leb128 (valueT value, int sign)
return sizeof_uleb128 (value);
}
-/* Output a LEB128 value. */
+/* Output a LEB128 value. Returns the number of bytes used. */
-static inline int
+static inline unsigned int
output_sleb128 (char *p, offsetT value)
{
char *orig = p;
@@ -5069,7 +5097,7 @@ output_sleb128 (char *p, offsetT value)
return p - orig;
}
-static inline int
+static inline unsigned int
output_uleb128 (char *p, valueT value)
{
char *orig = p;
@@ -5077,6 +5105,7 @@ output_uleb128 (char *p, valueT value)
do
{
unsigned byte = (value & 0x7f);
+
value >>= 7;
if (value != 0)
/* More bytes to follow. */
@@ -5089,7 +5118,7 @@ output_uleb128 (char *p, valueT value)
return p - orig;
}
-int
+unsigned int
output_leb128 (char *p, valueT value, int sign)
{
if (sign)
@@ -5100,10 +5129,11 @@ output_leb128 (char *p, valueT value, int sign)
/* Do the same for bignums. We combine sizeof with output here in that
we don't output for NULL values of P. It isn't really as critical as
- for "normal" values that this be streamlined. */
+ for "normal" values that this be streamlined. Returns the number of
+ bytes used. */
-static inline int
-output_big_sleb128 (char *p, LITTLENUM_TYPE *bignum, int size)
+static inline unsigned int
+output_big_sleb128 (char *p, LITTLENUM_TYPE *bignum, unsigned int size)
{
char *orig = p;
valueT val = 0;
@@ -5157,8 +5187,8 @@ output_big_sleb128 (char *p, LITTLENUM_TYPE *bignum, int size)
return p - orig;
}
-static inline int
-output_big_uleb128 (char *p, LITTLENUM_TYPE *bignum, int size)
+static inline unsigned int
+output_big_uleb128 (char *p, LITTLENUM_TYPE *bignum, unsigned int size)
{
char *orig = p;
valueT val = 0;
@@ -5196,8 +5226,8 @@ output_big_uleb128 (char *p, LITTLENUM_TYPE *bignum, int size)
return p - orig;
}
-static int
-output_big_leb128 (char *p, LITTLENUM_TYPE *bignum, int size, int sign)
+static unsigned int
+output_big_leb128 (char *p, LITTLENUM_TYPE *bignum, unsigned int size, int sign)
{
if (sign)
return output_big_sleb128 (p, bignum, size);
@@ -5270,23 +5300,25 @@ emit_leb128_expr (expressionS *exp, int sign)
/* If we've got a constant, emit the thing directly right now. */
valueT value = exp->X_add_number;
- int size;
+ unsigned int size;
char *p;
size = sizeof_leb128 (value, sign);
p = frag_more (size);
- output_leb128 (p, value, sign);
+ if (output_leb128 (p, value, sign) > size)
+ abort ();
}
else if (op == O_big)
{
/* O_big is a different sort of constant. */
- int size;
+ unsigned int size;
char *p;
size = output_big_leb128 (NULL, generic_bignum, exp->X_add_number, sign);
p = frag_more (size);
- output_big_leb128 (p, generic_bignum, exp->X_add_number, sign);
+ if (output_big_leb128 (p, generic_bignum, exp->X_add_number, sign) > size)
+ abort ();
}
else
{
diff --git a/gas/read.h b/gas/read.h
index c1b040a..146dc36 100644
--- a/gas/read.h
+++ b/gas/read.h
@@ -128,17 +128,17 @@ extern void emit_expr_with_reloc (expressionS *exp, unsigned int nbytes,
TC_PARSE_CONS_RETURN_TYPE);
extern void emit_expr_fix (expressionS *, unsigned int, fragS *, char *,
TC_PARSE_CONS_RETURN_TYPE);
-extern void equals (char *sym_name, int reassign);
-extern void float_cons (int float_type);
+extern void equals (char *, int);
+extern void float_cons (int);
extern void ignore_rest_of_line (void);
#define discard_rest_of_line ignore_rest_of_line
-extern int output_leb128 (char *, valueT, int sign);
+extern unsigned output_leb128 (char *, valueT, int);
extern void pseudo_set (symbolS * symbolP);
extern void read_a_source_file (char *name);
extern void read_begin (void);
extern void read_print_statistics (FILE *);
extern char *read_symbol_name (void);
-extern int sizeof_leb128 (valueT, int sign);
+extern unsigned sizeof_leb128 (valueT, int);
extern void stabs_generate_asm_file (void);
extern void stabs_generate_asm_lineno (void);
extern void stabs_generate_asm_func (const char *, const char *);
@@ -153,7 +153,7 @@ extern void generate_lineno_debug (void);
extern void s_abort (int) ATTRIBUTE_NORETURN;
extern void s_align_bytes (int arg);
extern void s_align_ptwo (int);
-extern void bss_alloc (symbolS *, addressT, int);
+extern void bss_alloc (symbolS *, addressT, unsigned);
extern offsetT parse_align (int);
extern symbolS *s_comm_internal (int, symbolS *(*) (int, symbolS *, addressT));
extern symbolS *s_lcomm_internal (int, symbolS *, addressT);
diff --git a/gas/write.c b/gas/write.c
index f9d5da9..46d8d96 100644
--- a/gas/write.c
+++ b/gas/write.c
@@ -355,12 +355,15 @@ record_alignment (/* Segment to which alignment pertains. */
segT seg,
/* Alignment, as a power of 2 (e.g., 1 => 2-byte
boundary, 2 => 4-byte boundary, etc.) */
- int align)
+ unsigned int align)
{
if (seg == absolute_section)
return;
- if ((unsigned int) align > bfd_get_section_alignment (stdoutput, seg))
+ if (align <= OCTETS_PER_BYTE_POWER)
+ return;
+
+ if (align > bfd_get_section_alignment (stdoutput, seg))
bfd_set_section_alignment (stdoutput, seg, align);
}
diff --git a/gas/write.h b/gas/write.h
index b1bc778..4aee78d 100644
--- a/gas/write.h
+++ b/gas/write.h
@@ -166,9 +166,9 @@ extern addressT dot_value;
extern fragS *dot_frag;
extern struct reloc_list* reloc_list;
-extern void append (char **charPP, char *fromP, unsigned long length);
-extern void record_alignment (segT seg, int align);
-extern int get_recorded_alignment (segT seg);
+extern void append (char **, char *, unsigned long);
+extern void record_alignment (segT, unsigned);
+extern int get_recorded_alignment (segT);
extern void write_object_file (void);
extern long relax_frag (segT, fragS *, long);
extern int relax_segment (struct frag *, segT, int);