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dynamic: Fix -U for -fpatchable-function-entry #1799

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merged 1 commit into from
Sep 12, 2023
Merged

dynamic: Fix -U for -fpatchable-function-entry #1799

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1 change: 1 addition & 0 deletions arch/x86_64/mcount-dynamic.c
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Original file line number Diff line number Diff line change
Expand Up @@ -623,6 +623,7 @@ int mcount_unpatch_func(struct mcount_dynamic_info *mdi, struct uftrace_symbol *

switch (mdi->type) {
case DYNAMIC_FENTRY:
case DYNAMIC_PATCHABLE:
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But there's nothing to unpatch for -fpatchable-function-entry as they are already NOPs.

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It does its job in the following example.

$ g++ -fpatchable-function-entry=5 example.cpp

$ uftrace record -P. -U ^std:: a.out

Since -P. asks patching all the available functions, we need a way to suppress the previous patching request.

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Ok, multiple updates also make it useful.

result = unpatch_fentry_func(mdi, sym);
break;

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14 changes: 13 additions & 1 deletion libmcount/dynamic.c
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Expand Up @@ -508,6 +508,8 @@ static void patch_patchable_func_matched(struct mcount_dynamic_info *mdi, struct
.size = UINT_MAX,
.name = namebuf,
};
bool found = false;
int match;
char *soname = get_soname(map->libname);

symtab = &map->mod->symtab;
Expand All @@ -531,9 +533,19 @@ static void patch_patchable_func_matched(struct mcount_dynamic_info *mdi, struct
continue;
}

mcount_patch_func_with_stats(mdi, sym);
found = true;
match = match_pattern_list(map, soname, sym->name);
if (!match)
continue;
else if (match == 1)
mcount_patch_func_with_stats(mdi, sym);
else
mcount_unpatch_func(mdi, sym, NULL);
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IIRC I saw this change in the Ciena's work.

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Right, it looks 151fb61 missed fixing patch_patchable_func_matched along with patch_normal_func_matched.

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As it has other problems, I think I can merge this one first.

}

if (!found)
stats.nomatch++;

free(soname);
}

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