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Rename MRB_USE_ETEXT_EDATA to MRB_USE_LINK_TIME_RO_DATA_P and support lld linked programs

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In lld linked programs, .rodata comes before .text, thus mrb_ro_data_p
will return false for strings in .rodata. Change the lower bound from
_etext to __ehdr_start to catch these cases. This works for ld.bfd, gold
and lld, and it does not have false positives even if .init_array does
not exist.

Remove the branch that uses _edata: strings in .data can be modified so
this is semantically incorrect. Delete the __APPLE__ branch (its
manpages say get_etext() and get_edata() are strongly discouraged).
.init_array has been adopted by most ELF platforms to supersede .ctors.

Neither _etext nor _edata is used, so rename MRB_USE_ETEXT_EDATA to
MRB_USE_EHDR_START.
This commit is contained in:
Fangrui Song
2019-09-16 07:44:05 -07:00
parent 8db7dfb5c4
commit 7f044341f9
4 changed files with 20 additions and 41 deletions
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include/mruby/value.h
+10 -22
View File
@@ -309,37 +309,25 @@ mrb_undef_value(void)
return v;
}
#if defined(MRB_USE_ETEXT_EDATA) && !defined(MRB_USE_LINK_TIME_RO_DATA_P)
# ifdef __GNUC__
# warning MRB_USE_ETEXT_EDATA is deprecated. Define MRB_USE_LINK_TIME_RO_DATA_P instead.
# endif
# define MRB_USE_LINK_TIME_RO_DATA_P
#endif
#if defined(MRB_USE_CUSTOM_RO_DATA_P)
/* If you define `MRB_USE_CUSTOM_RO_DATA_P`, you must implement `mrb_ro_data_p()`. */
mrb_bool mrb_ro_data_p(const char *p);
#elif defined(MRB_USE_ETEXT_EDATA)
#if (defined(__APPLE__) && defined(__MACH__))
#include <mach-o/getsect.h>
static inline mrb_bool
mrb_ro_data_p(const char *p)
{
return (const char*)get_etext() < p && p < (const char*)get_edata();
}
#else
extern char _etext[];
#ifdef MRB_NO_INIT_ARRAY_START
extern char _edata[];
static inline mrb_bool
mrb_ro_data_p(const char *p)
{
return _etext < p && p < _edata;
}
#else
#elif defined(MRB_USE_LINK_TIME_RO_DATA_P)
extern char __ehdr_start[];
extern char __init_array_start[];
static inline mrb_bool
mrb_ro_data_p(const char *p)
{
return _etext < p && p < (char*)&__init_array_start;
return __ehdr_start < p && p < __init_array_start;
}
#endif
#endif
#else
# define mrb_ro_data_p(p) FALSE
#endif