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lookup: fix Module.symvers reading for newer kernels 

With Linux commit 5190044c2965 ("modpost: move the namespace field in
Module.symvers last"), the format of Module.symvers has changed yet
again.

Use a completely different approach for figuring out the format.  If a
column has "vmlinux", assume that's the "Module" column.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
This commit is contained in:
Josh Poimboeuf 2020-04-14 09:57:19 -05:00
parent 1cc52bf19b
commit 4e0db559c1
1 changed files with 36 additions and 30 deletions
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66
kpatch-build/lookup.c
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@ -296,25 +296,44 @@ static void symtab_read(struct lookup_table *table, char *path)
}
/*
* Symvers file format is the following for kernels v5.3 and newer:
* <CRC> <Symbol> <Namespace> <Module> <Export Type>
* The Module.symvers file format is one of the following, depending on kernel
* version:
*
* Separated by tabs. <Namespace> can be blank (i.e. ""). Kernels before v5.3
* don't have namespace column at all.
* <CRC> <Symbol> <Module> <Export Type>
* <CRC> <Symbol> <Namespace> <Module> <Export Type>
* <CRC> <Symbol> <Module> <Export Type> <Namespace>
*
* All we care about is Symbol and Module. Since the format is unpredictable,
* we have to dynamically determine which column is Module by looking for
* "vmlinux".
*/
static void symvers_read(struct lookup_table *table, char *path)
{
FILE *file;
unsigned int i = 0;
int i, column, mod_column = 0;
char line[4096];
char *objname, *symname;
char *tmp, *objname, *symname;
if ((file = fopen(path, "r")) == NULL)
ERROR("fopen");
while (fgets(line, 4096, file))
while (fgets(line, 4096, file)) {
table->exp_nr++;
if (mod_column)
continue;
/* Find the module column */
for (column = 1, tmp = line; (tmp = strchr(tmp, '\t')); column++) {
tmp++;
if (*tmp && !strncmp(tmp, "vmlinux", 7))
mod_column = column;
}
}
if (table->exp_nr && !mod_column)
ERROR("Module.symvers: invalid format");
table->exp_syms = malloc(table->exp_nr * sizeof(*table->exp_syms));
if (!table->exp_syms)
ERROR("malloc table.exp_syms");
@ -322,32 +341,20 @@ static void symvers_read(struct lookup_table *table, char *path)
table->exp_nr * sizeof(*table->exp_syms));
rewind(file);
for (i = 0; fgets(line, 4096, file); i++) {
char *name = NULL, *mod = NULL;
while (fgets(line, 4096, file)) {
char *name, *namespace, *mod, *tmp;
if (!(name = strchr(line, '\t')))
continue;
*name++ = '\0';
if (!(namespace = strchr(name, '\t')))
continue;
*namespace++ = '\0';
if (!(mod = strchr(namespace, '\t')))
continue;
*mod++ = '\0';
if ((tmp = strchr(mod, '\t')) != NULL) {
for (column = 1, tmp = line; (tmp = strchr(tmp, '\t')); column++) {
*tmp++ = '\0';
} else {
/*
* Looks like it's an old symvers file with no
* namespace column.
*/
mod = namespace;
if (*tmp && column == 1)
name = tmp;
else if (*tmp && column == mod_column)
mod = tmp;
}
if (!name || !mod)
continue;
symname = strdup(name);
if (!symname)
perror("strdup");
@ -356,7 +363,6 @@ static void symvers_read(struct lookup_table *table, char *path)
table->exp_syms[i].name = symname;
table->exp_syms[i].objname = objname;
i++;
}
fclose(file);