So that when we apply the patch again the .bss is cleared.
Otherwise we may find some variables containing old values.
The payloads may contain various .bss - especially if -fdata-sections
is used which can create .bss.<name> sections.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
---
Cc: Ross Lagerwall <ross.lagerw...@citrix.com>
Cc: Jan Beulich <jbeul...@suse.com>
v3: Initial submission
v4: s/EINVAL/EOPNOTSUPP/
Do memset in a single place
Support multiple BSS sections.
---
xen/common/livepatch.c | 60 ++++++++++++++++++++++++++++++++++++++------------
1 file changed, 46 insertions(+), 14 deletions(-)
diff --git a/xen/common/livepatch.c b/xen/common/livepatch.c
index 5da28a3..b5aef57 100644
--- a/xen/common/livepatch.c
+++ b/xen/common/livepatch.c
@@ -70,6 +70,9 @@ struct payload {
unsigned int nsyms; /* Nr of entries in .strtab and
symbols. */
struct livepatch_build_id id; /* ELFNOTE_DESC(.note.gnu.build-id)
of the payload. */
struct livepatch_build_id dep; /* ELFNOTE_DESC(.livepatch.depends).
*/
+ void **bss; /* .bss's of the payload. */
+ size_t *bss_size; /* and their sizes. */
+ size_t n_bss; /* Size of the array. */
char name[XEN_LIVEPATCH_NAME_SIZE]; /* Name of it. */
};
@@ -255,12 +258,18 @@ static struct payload *find_payload(const char *name)
static void free_payload_data(struct payload *payload)
{
/* Set to zero until "move_payload". */
- if ( !payload->pages )
- return;
-
- vfree((void *)payload->text_addr);
+ if ( payload->pages )
+ {
+ vfree((void *)payload->text_addr);
+ payload->pages = 0;
+ }
- payload->pages = 0;
+ if ( payload->n_bss )
+ {
+ xfree(payload->bss);
+ xfree(payload->bss_size);
+ payload->n_bss = 0;
+ }
}
/*
@@ -287,6 +296,7 @@ static int move_payload(struct payload *payload, struct
livepatch_elf *elf)
unsigned int i;
size_t size = 0;
unsigned int *offset;
+ unsigned int n_bss = 0;
int rc = 0;
offset = xmalloc_array(unsigned int, elf->hdr->e_shnum);
@@ -309,7 +319,11 @@ static int move_payload(struct payload *payload, struct
livepatch_elf *elf)
calc_section(&elf->sec[i], &payload->text_size, &offset[i]);
else if ( !(elf->sec[i].sec->sh_flags & SHF_EXECINSTR) &&
(elf->sec[i].sec->sh_flags & SHF_WRITE) )
+ {
calc_section(&elf->sec[i], &payload->rw_size, &offset[i]);
+ if ( elf->sec[i].sec->sh_type == SHT_NOBITS )
+ n_bss++;
+ }
else if ( !(elf->sec[i].sec->sh_flags & SHF_EXECINSTR) &&
!(elf->sec[i].sec->sh_flags & SHF_WRITE) )
calc_section(&elf->sec[i], &payload->ro_size, &offset[i]);
@@ -334,12 +348,8 @@ static int move_payload(struct payload *payload, struct
livepatch_elf *elf)
size = PFN_UP(size); /* Nr of pages. */
text_buf = vmalloc_xen(size * PAGE_SIZE);
if ( !text_buf )
- {
- dprintk(XENLOG_ERR, LIVEPATCH "%s: Could not allocate memory for
payload!\n",
- elf->name);
- rc = -ENOMEM;
- goto out;
- }
+ goto out_mem;
+
rw_buf = text_buf + PAGE_ALIGN(payload->text_size);
ro_buf = rw_buf + PAGE_ALIGN(payload->rw_size);
@@ -348,6 +358,14 @@ static int move_payload(struct payload *payload, struct
livepatch_elf *elf)
payload->rw_addr = rw_buf;
payload->ro_addr = ro_buf;
+ payload->bss = xmalloc_array(void *, n_bss);
+ payload->bss_size = xmalloc_array(size_t, n_bss);
+ if ( !payload->bss || !payload->bss_size )
+ goto out_mem;
+
+ payload->n_bss = n_bss;
+ n_bss = 0; /* Reusing as counter. */
+
for ( i = 1; i < elf->hdr->e_shnum; i++ )
{
if ( elf->sec[i].sec->sh_flags & SHF_ALLOC )
@@ -374,14 +392,24 @@ static int move_payload(struct payload *payload, struct
livepatch_elf *elf)
elf->name, elf->sec[i].name, elf->sec[i].load_addr);
}
else
- memset(elf->sec[i].load_addr, 0, elf->sec[i].sec->sh_size);
+ {
+ payload->bss[n_bss] = elf->sec[i].load_addr;
+ payload->bss_size[n_bss++] = elf->sec[i].sec->sh_size;
+ }
}
}
+ ASSERT(n_bss == payload->n_bss);
out:
xfree(offset);
return rc;
+
+ out_mem:
+ dprintk(XENLOG_ERR, LIVEPATCH "%s: Could not allocate memory for
payload!\n",
+ elf->name);
+ rc = -ENOMEM;
+ goto out;
}
static int secure_payload(struct payload *payload, struct livepatch_elf *elf)
@@ -997,6 +1025,10 @@ static int apply_payload(struct payload *data)
printk(XENLOG_INFO LIVEPATCH "%s: Applying %u functions\n",
data->name, data->nfuncs);
+ /* And clear the BSS for subsequent operation. */
+ for ( i = 0; i < data->n_bss; i++ )
+ memset(data->bss[i], 0, data->bss_size[i]);
+
arch_livepatch_quiesce();
for ( i = 0; i < data->nfuncs; i++ )
@@ -1513,9 +1545,9 @@ static void livepatch_printall(unsigned char key)
list_for_each_entry ( data, &payload_list, list )
{
- printk(" name=%s state=%s(%d) %p (.data=%p, .rodata=%p) using %u
pages.\n",
+ printk(" name=%s state=%s(%d) %p (.data=%p, .rodata=%p) using %u pages
(%zu .bss).\n",
data->name, state2str(data->state), data->state,
data->text_addr,
- data->rw_addr, data->ro_addr, data->pages);
+ data->rw_addr, data->ro_addr, data->pages, data->n_bss);
for ( i = 0; i < data->nfuncs; i++ )
{
--
2.4.11
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