[patch] Improve ELF symbols preference (global > weak)
Jan Kratochvil
jan.kratochvil at redhat.com
Tue Oct 9 18:34:38 UTC 2012
On Tue, 09 Oct 2012 20:14:51 +0200, Roland McGrath wrote:
> Don't use a macro. Use a nested inline function.
> I'd make it:
> /* Return true if A's binding is preferable to B's. */
> bool binding_preferred (const GElf_Sym *a, const GElf_Sym *b)
> (But season to taste.)
The comparison is there in both > and >= form so I do not find such function
too convenient with two parameters.
Thanks,
Jan
libdwfl/
2012-10-09 Jan Kratochvil <jan.kratochvil at redhat.com>
* dwfl_module_addrsym.c (dwfl_module_addrsym): New function
binding_value. Use it for both zero and non-zero size symbols
comparisons.
tests/
2012-10-09 Jan Kratochvil <jan.kratochvil at redhat.com>
* run-addrname-test.sh: New test for symbol preferences.
* testfile64.bz2: New file.
diff --git a/libdwfl/dwfl_module_addrsym.c b/libdwfl/dwfl_module_addrsym.c
index 4e0646e..84ce3d4 100644
--- a/libdwfl/dwfl_module_addrsym.c
+++ b/libdwfl/dwfl_module_addrsym.c
@@ -106,12 +106,26 @@ dwfl_module_addrsym (Dwfl_Module *mod, GElf_Addr addr,
if (sym.st_size == 0 || addr - sym.st_value < sym.st_size)
{
+ /* Return GELF_ST_BIND as higher-is-better integer. */
+ inline int binding_value (const GElf_Sym *symp)
+ {
+ switch (GELF_ST_BIND (symp->st_info))
+ {
+ case STB_GLOBAL:
+ return 3;
+ case STB_WEAK:
+ return 2;
+ case STB_LOCAL:
+ return 1;
+ default:
+ return 0;
+ }
+ }
/* This symbol is a better candidate than the current one
if it's closer to ADDR or is global when it was local. */
if (closest_name == NULL
|| closest_sym->st_value < sym.st_value
- || (GELF_ST_BIND (closest_sym->st_info)
- < GELF_ST_BIND (sym.st_info)))
+ || binding_value (closest_sym) < binding_value (&sym))
{
if (sym.st_size != 0)
{
@@ -133,13 +147,17 @@ dwfl_module_addrsym (Dwfl_Module *mod, GElf_Addr addr,
}
}
/* When the beginning of its range is no closer,
- the end of its range might be. But do not
- replace a global symbol with a local! */
+ the end of its range might be. Otherwise follow
+ GELF_ST_BIND preference. If all are equal prefer
+ the first symbol found. */
else if (sym.st_size != 0
&& closest_sym->st_value == sym.st_value
- && closest_sym->st_size > sym.st_size
- && (GELF_ST_BIND (closest_sym->st_info)
- <= GELF_ST_BIND (sym.st_info)))
+ && ((closest_sym->st_size > sym.st_size
+ && (binding_value (closest_sym)
+ <= binding_value (&sym)))
+ || (closest_sym->st_size >= sym.st_size
+ && (binding_value (closest_sym)
+ < binding_value (&sym)))))
{
*closest_sym = sym;
closest_shndx = shndx;
diff --git a/tests/run-addrname-test.sh b/tests/run-addrname-test.sh
index 3531643..034cf6f 100755
--- a/tests/run-addrname-test.sh
+++ b/tests/run-addrname-test.sh
@@ -211,4 +211,85 @@ local_outer+0x9
??:0
EOF
+# .macro global label size
+#\label: .globl \label
+# .size \label, \size
+# .endm
+# .macro weak label size
+#\label: .weak \label
+# .size \label, \size
+# .endm
+# .macro local label size
+#\label: .size \label, \size
+# .endm
+# .macro offset val
+# .ifne (. - _start) - \val
+# .err
+# .endif
+# .byte \val
+# .endm
+#
+#_start:
+# offset 0
+#
+# local glocal, 1
+# weak gweak, 1
+# global gglobal1, 2
+# global gglobal2, 1
+# global gglobal3, 1
+# offset 1
+# /* Symbols end here. */
+# offset 2
+# /* gglobal1 ends here. */
+# offset 3
+#
+# local g0local, 0
+# weak g0weak, 0
+# global g0global1, 0
+# global g0global2, 0
+# offset 4
+#
+# local wlocal, 1
+# weak wweak1, 2
+# weak wweak2, 1
+# weak wweak3, 1
+# offset 5
+# /* Symbols end here. */
+# offset 6
+# /* wweak1 ends here. */
+# offset 7
+#
+# local w0local, 0
+# weak w0weak1, 0
+# weak w0weak2, 0
+# offset 8
+#
+# local llocal1, 2
+# local llocal2, 1
+# local llocal3, 1
+# offset 9
+# /* Symbols end here. */
+# offset 10
+# /* llocal1 ends here. */
+# offset 11
+#
+# local l0local1, 0
+# local l0local2, 0
+# offset 12
+testfiles testfile64
+testrun_compare ../src/addr2line -S -e testfile64 1 4 5 8 9 12 <<\EOF
+gglobal2
+??:0
+g0global2
+??:0
+wweak2
+??:0
+w0weak2
+??:0
+llocal2
+??:0
+l0local2
+??:0
+EOF
+
exit 0
diff --git a/tests/testfile64.bz2 b/tests/testfile64.bz2
new file mode 100644
index 0000000000000000000000000000000000000000..674bd5397137e49a3781b04cb50018d937340011
GIT binary patch
literal 395
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zYX+<|(v#IUpriFqQ`9ufp!A-TCPsq at dYUs(XQ)Pmrh%Xao}d5#0iXZ?2 at z9M(HR;5
zXahq=hCtD#ng*DJiwmabqM7gEtAsjEIf9~vRiA<f9`>pd2~C&Z1o9(GUTGSJ61fo&
z%_5RFm8&WNFvKLWHGqIquWbPWkizy0|2ZfNKKXNI&-+SCb)<x9qTQ)4-c5}Vg)I$<
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pTM&vjR<)mpw7j*1N{*Du34jUjIIUqy29p1axgwk>NLBLcV1V8+t4RO=
literal 0
HcmV?d00001
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