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Kernel linkers: add emergency sysctl to restore old behavior

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allowing linking to static symbols from other files.  Default the new
settings to true, delaying the change of the kernel linker behavior
for other day.

Suggested by:	emaste
PR:	207898
Reviewed by:	emaste, markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D32878
This commit is contained in:
Konstantin Belousov 2021-11-07 11:26:26 +02:00
parent 95c20faf11
commit ecd8245e0d
2 changed files with 19 additions and 2 deletions
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9
sys/kern/link_elf.c
View file

@ -194,6 +194,11 @@ static struct linker_class link_elf_class = {
link_elf_methods, sizeof(struct elf_file)
};
static bool link_elf_leak_locals = true;
SYSCTL_BOOL(_debug, OID_AUTO, link_elf_leak_locals,
CTLFLAG_RWTUN, &link_elf_leak_locals, 0,
"Allow local symbols to participate in global module symbol resolution");
typedef int (*elf_reloc_fn)(linker_file_t lf, Elf_Addr relocbase,
const void *data, int type, elf_lookup_fn lookup);
@ -1552,6 +1557,8 @@ link_elf_lookup_symbol1(linker_file_t lf, const char *name, c_linker_sym_t *sym,
static int
link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
{
if (link_elf_leak_locals)
return (link_elf_lookup_debug_symbol(lf, name, sym));
return (link_elf_lookup_symbol1(lf, name, sym, false));
}
@ -1612,6 +1619,8 @@ static int
link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
linker_symval_t *symval)
{
if (link_elf_leak_locals)
return (link_elf_debug_symbol_values(lf, sym, symval));
return (link_elf_symbol_values1(lf, sym, symval, false));
}

12
sys/kern/link_elf_obj.c
View file

@ -44,6 +44,7 @@ __FBSDID("$FreeBSD$");
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/rwlock.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <machine/elf.h>
@ -183,6 +184,11 @@ static struct linker_class link_elf_class = {
link_elf_methods, sizeof(struct elf_file)
};
static bool link_elf_obj_leak_locals = true;
SYSCTL_BOOL(_debug, OID_AUTO, link_elf_obj_leak_locals,
CTLFLAG_RWTUN, &link_elf_obj_leak_locals, 0,
"Allow local symbols to participate in global module symbol resolution");
static int relocate_file(elf_file_t ef);
static void elf_obj_cleanup_globals_cache(elf_file_t);
@ -1455,7 +1461,8 @@ link_elf_lookup_symbol1(linker_file_t lf, const char *name, c_linker_sym_t *sym,
static int
link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
{
return (link_elf_lookup_symbol1(lf, name, sym, false));
return (link_elf_lookup_symbol1(lf, name, sym,
link_elf_obj_leak_locals));
}
static int
@ -1494,7 +1501,8 @@ static int
link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
linker_symval_t *symval)
{
return (link_elf_symbol_values1(lf, sym, symval, false));
return (link_elf_symbol_values1(lf, sym, symval,
link_elf_obj_leak_locals));
}
static int