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kpatch-build: detect special section group sizes 

Hard-coding the special section group sizes is unreliable.  Instead,
determine them dynamically by finding the related struct definitions in
the DWARF metadata.

Fixes #517.
Fixes #523.
This commit is contained in:
Josh Poimboeuf 2015-10-27 11:12:56 -05:00
parent a1db97bd7c
commit 1704498471
2 changed files with 91 additions and 6 deletions
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71
kpatch-build/create-diff-object.c
View File

@ -1680,11 +1680,70 @@ void kpatch_reindex_elements(struct kpatch_elf *kelf)
}
int bug_table_group_size(struct kpatch_elf *kelf, int offset) { return 12; }
int smp_locks_group_size(struct kpatch_elf *kelf, int offset) { return 4; }
int parainstructions_group_size(struct kpatch_elf *kelf, int offset) { return 16; }
int ex_table_group_size(struct kpatch_elf *kelf, int offset) { return 8; }
int altinstructions_group_size(struct kpatch_elf *kelf, int offset) { return 12; }
int bug_table_group_size(struct kpatch_elf *kelf, int offset)
{
static int size = 0;
char *str;
if (!size) {
str = getenv("BUG_STRUCT_SIZE");
if (!str)
ERROR("BUG_STRUCT_SIZE not set");
size = atoi(str);
}
return size;
}
int parainstructions_group_size(struct kpatch_elf *kelf, int offset)
{
static int size = 0;
char *str;
if (!size) {
str = getenv("PARA_STRUCT_SIZE");
if (!str)
ERROR("PARA_STRUCT_SIZE not set");
size = atoi(str);
}
return size;
}
int ex_table_group_size(struct kpatch_elf *kelf, int offset)
{
static int size = 0;
char *str;
if (!size) {
str = getenv("EX_STRUCT_SIZE");
if (!str)
ERROR("EX_STRUCT_SIZE not set");
size = atoi(str);
}
return size;
}
int altinstructions_group_size(struct kpatch_elf *kelf, int offset)
{
static int size = 0;
char *str;
if (!size) {
str = getenv("ALT_STRUCT_SIZE");
if (!str)
ERROR("ALT_STRUCT_SIZE not set");
size = atoi(str);
}
return size;
}
int smp_locks_group_size(struct kpatch_elf *kelf, int offset)
{
return 4;
}
/*
* The rela groups in the .fixup section vary in size. The beginning of each
@ -1752,7 +1811,7 @@ struct special_section special_sections[] = {
.group_size = fixup_group_size,
},
{
.name = "__ex_table",
.name = "__ex_table", /* must come after .fixup */
.group_size = ex_table_group_size,
},
{

26
kpatch-build/kpatch-build
View File

@ -452,6 +452,32 @@ cp "$PATCHFILE" "$APPLIEDPATCHFILE" || die
cp -LR "$DATADIR/patch" "$TEMPDIR" || die
export KCFLAGS="-I$DATADIR/patch -ffunction-sections -fdata-sections"
echo "Reading special section data"
SPECIAL_VARS=$(readelf -wi "$VMLINUX" |
gawk --non-decimal-data '
BEGIN { a = b = p = e = 0 }
a == 0 && /DW_AT_name.* alt_instr$/ {a = 1; next}
b == 0 && /DW_AT_name.* bug_entry$/ {b = 1; next}
p == 0 && /DW_AT_name.* paravirt_patch_site$/ {p = 1; next}
e == 0 && /DW_AT_name.* exception_table_entry$/ {e = 1; next}
a == 1 {printf("export ALT_STRUCT_SIZE=%d\n", $4); a = 2}
b == 1 {printf("export BUG_STRUCT_SIZE=%d\n", $4); b = 2}
p == 1 {printf("export PARA_STRUCT_SIZE=%d\n", $4); p = 2}
e == 1 {printf("export EX_STRUCT_SIZE=%d\n", $4); e = 2}
a == 2 && b == 2 && p == 2 && e == 2 {exit}')
[[ -n $SPECIAL_VARS ]] && eval "$SPECIAL_VARS"
if [[ -z $ALT_STRUCT_SIZE ]] || [[ -z $BUG_STRUCT_SIZE ]] ||
[[ -z $PARA_STRUCT_SIZE ]] || [[ -z $EX_STRUCT_SIZE ]]; then
die "can't find special struct size"
fi
for i in $ALT_STRUCT_SIZE $BUG_STRUCT_SIZE $PARA_STRUCT_SIZE $EX_STRUCT_SIZE; do
if [[ ! $i -gt 0 ]] || [[ ! $i -le 16 ]]; then
die "invalid special struct size $i"
fi
done
echo "Building original kernel"
./scripts/setlocalversion --save-scmversion || die
make mrproper >> "$LOGFILE" 2>&1 || die