Re: [PATCH 01/10] symbols: prefix static symbols with their source file name

[Ian Campbell <ian.campbell@citrix.com>]

On Tue, 2015-10-20 at 04:38 -0600, Jan Beulich wrote:
> This requires adjustments to the tool generating the symbol table and
> its as well as nm's invocation.
> 
> Note: Not warning about duplicate symbols in the EFI case for now, as
> a binutils bug causes misnamed file name entries to appear in EFI
> binaries' symbol tables when the file name is longer than 18 chars.
> (Not doing so also avoids other duplicates getting printed twice.)
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> No changing ARM for now, as xSplice isn't targeted at it just yet.

The improved information from e.g. stack traces (which I'm supposing this
also enables) seems valuable on ARM too. Is this something you plan to add
or shall we ARM folks add it to our todo?

I suspect the answer is no, but do you think there is much scope for making
some of these complex linker runes common instead of arch specific?

>From what I can tell the actual arch change here is s/-n/-pa/ on the NM
invocation (numeric sort => no sort + include debugger symbols) and then
add --sysv --sort and optionally --want-dup to the tools/symbols
invocation. Is it really as simple as that?

Given we don't do a special EFI build/link I think on ARM we do want --warn
-dup if at all possible.

Ian.

> --- a/xen/arch/x86/Makefile
> +++ b/xen/arch/x86/Makefile
> @@ -106,11 +106,13 @@ $(BASEDIR)/common/symbols-dummy.o:
>  $(TARGET)-syms: prelink.o xen.lds $(BASEDIR)/common/symbols-dummy.o
>  	$(LD) $(LDFLAGS) -T xen.lds -N prelink.o \
>  	    $(BASEDIR)/common/symbols-dummy.o -o $(@D)/.$(@F).0
> -	$(NM) -n $(@D)/.$(@F).0 | $(BASEDIR)/tools/symbols
> >$(@D)/.$(@F).0.S
> +	$(NM) -pa --format=sysv $(@D)/.$(@F).0 \
> +		| $(BASEDIR)/tools/symbols --sysv --sort
> >$(@D)/.$(@F).0.S
>  	$(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).0.o
>  	$(LD) $(LDFLAGS) -T xen.lds -N prelink.o \
>  	    $(@D)/.$(@F).0.o -o $(@D)/.$(@F).1
> -	$(NM) -n $(@D)/.$(@F).1 | $(BASEDIR)/tools/symbols
> >$(@D)/.$(@F).1.S
> +	$(NM) -pa --format=sysv $(@D)/.$(@F).1 \
> +		| $(BASEDIR)/tools/symbols --sysv --sort --warn-dup
> >$(@D)/.$(@F).1.S
>  	$(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).1.o
>  	$(LD) $(LDFLAGS) -T xen.lds -N prelink.o \
>  	    $(@D)/.$(@F).1.o -o $@
> @@ -133,13 +135,15 @@ $(TARGET).efi: prelink-efi.o efi.lds efi
>  	          $(guard) $(LD) $(call EFI_LDFLAGS,$(base)) -T efi.lds 
> -N $< efi/relocs-dummy.o \
>  	                $(BASEDIR)/common/symbols-dummy.o -o
> $(@D)/.$(@F).$(base).0 &&) :
>  	$(guard) efi/mkreloc $(foreach base,$(VIRT_BASE)
> $(ALT_BASE),$(@D)/.$(@F).$(base).0) >$(@D)/.$(@F).0r.S
> -	$(guard) $(NM) -n $(@D)/.$(@F).$(VIRT_BASE).0 | $(guard)
> $(BASEDIR)/tools/symbols >$(@D)/.$(@F).0s.S
> +	$(guard) $(NM) -pa --format=sysv $(@D)/.$(@F).$(VIRT_BASE).0 \
> +		| $(guard) $(BASEDIR)/tools/symbols --sysv --sort
> >$(@D)/.$(@F).0s.S
>  	$(guard) $(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).0r.o
> $(@D)/.$(@F).0s.o
>  	$(foreach base, $(VIRT_BASE) $(ALT_BASE), \
>  	          $(guard) $(LD) $(call EFI_LDFLAGS,$(base)) -T efi.lds 
> -N $< \
>  	                $(@D)/.$(@F).0r.o $(@D)/.$(@F).0s.o -o
> $(@D)/.$(@F).$(base).1 &&) :
>  	$(guard) efi/mkreloc $(foreach base,$(VIRT_BASE)
> $(ALT_BASE),$(@D)/.$(@F).$(base).1) >$(@D)/.$(@F).1r.S
> -	$(guard) $(NM) -n $(@D)/.$(@F).$(VIRT_BASE).1 | $(guard)
> $(BASEDIR)/tools/symbols >$(@D)/.$(@F).1s.S
> +	$(guard) $(NM) -pa --format=sysv $(@D)/.$(@F).$(VIRT_BASE).1 \
> +		| $(guard) $(BASEDIR)/tools/symbols --sysv --sort
> >$(@D)/.$(@F).1s.S
>  	$(guard) $(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).1r.o
> $(@D)/.$(@F).1s.o
>  	$(guard) $(LD) $(call EFI_LDFLAGS,$(VIRT_BASE)) -T efi.lds -N $<
> \
>  	                $(@D)/.$(@F).1r.o $(@D)/.$(@F).1s.o -o $@
> --- a/xen/tools/symbols.c
> +++ b/xen/tools/symbols.c
> @@ -30,6 +30,7 @@
>  #include <stdlib.h>
>  #include <string.h>
>  #include <stdint.h>
> +#include <stdbool.h>
>  #include <ctype.h>
>  
>  #define KSYM_NAME_LEN		127
> @@ -40,13 +41,14 @@ struct sym_entry {
>  	unsigned int len;
>  	unsigned char *sym;
>  };
> -
> +#define SYMBOL_NAME(s) ((char *)(s)->sym + 1)
>  
>  static struct sym_entry *table;
>  static unsigned int table_size, table_cnt;
>  static unsigned long long _stext, _etext, _sinittext, _einittext,
> _sextratext, _eextratext;
>  static int all_symbols = 0;
>  static char symbol_prefix_char = '\0';
> +static enum { fmt_bsd, fmt_sysv } input_format;
>  
>  int token_profit[0x10000];
>  
> @@ -73,11 +75,25 @@ static inline int is_arm_mapping_symbol(
>  
>  static int read_symbol(FILE *in, struct sym_entry *s)
>  {
> -	char str[500];
> +	char str[500], type[20] = "";
>  	char *sym, stype;
> -	int rc;
> -
> -	rc = fscanf(in, "%llx %c %499s\n", &s->addr, &stype, str);
> +	static enum { symbol, source_file, object_file } last;
> +	static char *filename;
> +	int rc = -1;
> +
> +	switch (input_format) {
> +	case fmt_bsd:
> +		rc = fscanf(in, "%llx %c %499s\n", &s->addr, &stype,
> str);
> +		break;
> +	case fmt_sysv:
> +		while (fscanf(in, "\n") == 1)
> +			/* nothing */;
> +		rc = fscanf(in, "%499[^ |] |%llx | %c |",
> +			    str, &s->addr, &stype);
> +		if (rc == 3 && fscanf(in, " %19[^ |] |", type) != 1)
> +			*type = '\0';
> +		break;
> +	}
>  	if (rc != 3) {
>  		if (rc != EOF) {
>  			/* skip line */
> @@ -87,6 +103,28 @@ static int read_symbol(FILE *in, struct 
>  		return -1;
>  	}
>  
> +	sym = strrchr(str, '.');
> +	if (strcasecmp(type, "FILE") == 0 ||
> +	    (/* GNU nm prior to XXX doesn't produce a type for EFI
> binaries. */
> +	     input_format == fmt_sysv && !*type && stype == '?' && sym
> &&
> +	     sym[1] && strchr("cSsoh", sym[1]) && !sym[2])) {
> +		/*
> +		 * gas prior to XXX outputs symbol table entries
> resulting
> +		 * from .file in reverse order. If we get two
> consecutive file
> +		 * symbols, prefer the first one if that names an object
> file
> +		 * (to cover multiply compiled files).
> +		 */
> +		if ((sym && sym[1] == 'o') || last != object_file) {
> +			free(filename);
> +			filename = *str ? strdup(str) : NULL;
> +		}
> +		last = !sym || sym[1] != 'o' ? source_file :
> object_file;
> +		goto skip_tail;
> +	}
> +
> +	last = symbol;
> +	rc = -1;
> +
>  	sym = str;
>  	/* skip prefix char */
>  	if (symbol_prefix_char && str[0] == symbol_prefix_char)
> @@ -109,24 +147,37 @@ static int read_symbol(FILE *in, struct 
>  	{
>  		/* Keep these useful absolute symbols */
>  		if (strcmp(sym, "__gp"))
> -			return -1;
> -
> +			goto skip_tail;
>  	}
>  	else if (toupper((uint8_t)stype) == 'U' ||
> +		 toupper((uint8_t)stype) == 'N' ||
>  		 is_arm_mapping_symbol(sym))
> -		return -1;
> +		goto skip_tail;
>  	/* exclude also MIPS ELF local symbols ($L123 instead of .L123)
> */
>  	else if (str[0] == '$')
> -		return -1;
> +		goto skip_tail;
>  
>  	/* include the type field in the symbol name, so that it gets
>  	 * compressed together */
>  	s->len = strlen(str) + 1;
> +	if (islower(stype) && filename)
> +		s->len += strlen(filename) + 1;
>  	s->sym = malloc(s->len + 1);
> -	strcpy((char *)s->sym + 1, str);
> +	sym = SYMBOL_NAME(s);
> +	if (islower(stype) && filename) {
> +		sym = stpcpy(sym, filename);
> +		*sym++ = '#';
> +	}
> +	strcpy(sym, str);
>  	s->sym[0] = stype;
>  
> -	return 0;
> +	rc = 0;
> +
> + skip_tail:
> +	if (input_format == fmt_sysv)
> +		fgets(str, 500, in); /* discard rest of line */
> +
> +	return rc;
>  }
>  
>  static int symbol_valid(struct sym_entry *s)
> @@ -460,11 +512,37 @@ static void optimize_token_table(void)
>  	optimize_result();
>  }
>  
> +static int compare_value(const void *p1, const void *p2)
> +{
> +	const struct sym_entry *sym1 = p1;
> +	const struct sym_entry *sym2 = p2;
> +
> +	if (sym1->addr < sym2->addr)
> +		return -1;
> +	if (sym1->addr > sym2->addr)
> +		return +1;
> +	/* Prefer global symbols. */
> +	if (isupper(*sym1->sym))
> +		return -1;
> +	if (isupper(*sym2->sym))
> +		return +1;
> +	return 0;
> +}
> +
> +static int compare_name(const void *p1, const void *p2)
> +{
> +	const struct sym_entry *sym1 = p1;
> +	const struct sym_entry *sym2 = p2;
> +
> +	return strcmp(SYMBOL_NAME(sym1), SYMBOL_NAME(sym2));
> +}
>  
>  int main(int argc, char **argv)
>  {
> +	unsigned int i;
> +	bool unsorted = false, warn_dup = false;
> +
>  	if (argc >= 2) {
> -		int i;
>  		for (i = 1; i < argc; i++) {
>  			if(strcmp(argv[i], "--all-symbols") == 0)
>  				all_symbols = 1;
> @@ -474,13 +552,36 @@ int main(int argc, char **argv)
>  				if ((*p == '"' && *(p+2) == '"') || (*p
> == '\'' && *(p+2) == '\''))
>  					p++;
>  				symbol_prefix_char = *p;
> -			} else
> +			} else if (strcmp(argv[i], "--sysv") == 0)
> +				input_format = fmt_sysv;
> +			else if (strcmp(argv[i], "--sort") == 0)
> +				unsorted = true;
> +			else if (strcmp(argv[i], "--warn-dup") == 0)
> +				warn_dup = true;
> +			else
>  				usage();
>  		}
>  	} else if (argc != 1)
>  		usage();
>  
>  	read_map(stdin);
> +
> +	if (warn_dup) {
> +		qsort(table, table_cnt, sizeof(*table), compare_name);
> +		for (i = 1; i < table_cnt; ++i)
> +			if (strcmp(SYMBOL_NAME(table + i - 1),
> +				   SYMBOL_NAME(table + i)) == 0 &&
> +			    table[i - 1].addr != table[i].addr)
> +				fprintf(stderr,
> +					"Duplicate symbol '%s' (%llx !=
> %llx)\n",
> +					SYMBOL_NAME(table + i),
> +					table[i].addr, table[i -
> 1].addr);
> +		unsorted = true;
> +	}
> +
> +	if (unsorted)
> +		qsort(table, table_cnt, sizeof(*table), compare_value);
> +
>  	optimize_token_table();
>  	write_src();
>  
> 
>