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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH 2/2] xen/version: Remove xen_build_id() and export the variable instead
The API is unergonomic to use, and leads to poor code generation because of
unnecessary forcing of data to the stack.
Rename build_id_p to xen_build_id, and build_id_len to xen_build_id_len, make
them __ro_after_init, and export the variables directly.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Anthony PERARD <anthony.perard@xxxxxxxxxx>
CC: Michal Orzel <michal.orzel@xxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
Both the code diffstat, and the binary on x86 speaks for themselves:
add/remove: 1/2 grow/shrink: 0/6 up/down: 4/-348 (-344)
Function old new delta
xen_build_id_len - 4 +4
build_id_len 4 - -4
build_id_p 8 - -8
xen_build_id 42 8 -34
livepatch_printall 470 432 -38
build_id_dep 152 113 -39
livepatch_op 7930 7866 -64
do_xen_version 2436 2363 -73
livepatch_op.cold 1420 1332 -88
---
xen/common/kernel.c | 14 ++++----------
xen/common/livepatch.c | 23 ++++++++++-------------
xen/common/version.c | 25 +++++++------------------
xen/include/xen/version.h | 4 +++-
4 files changed, 24 insertions(+), 42 deletions(-)
diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index 5be668ba855a..e6979352e100 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -510,21 +510,15 @@ static long xenver_varbuf_op(int cmd,
XEN_GUEST_HANDLE_PARAM(void) arg)
struct xen_varbuf user_str;
const char *str = NULL;
size_t sz;
- int rc;
switch ( cmd )
{
case XENVER_build_id:
- {
- unsigned int local_sz;
-
- rc = xen_build_id((const void **)&str, &local_sz);
- if ( rc )
- return rc;
-
- sz = local_sz;
+ str = xen_build_id;
+ sz = xen_build_id_len;
+ if ( !sz )
+ return -ENODATA;
goto have_len;
- }
case XENVER_extraversion2:
str = xen_extra_version();
diff --git a/xen/common/livepatch.c b/xen/common/livepatch.c
index 9a0df5363b59..9285f88644f4 100644
--- a/xen/common/livepatch.c
+++ b/xen/common/livepatch.c
@@ -475,8 +475,8 @@ static int parse_buildid(const struct livepatch_elf_sec
*sec,
static int check_xen_buildid(const struct livepatch_elf *elf)
{
- const void *id;
- unsigned int len;
+ const void *id = xen_build_id;
+ unsigned int len = xen_build_id_len;
struct livepatch_build_id lp_id;
const struct livepatch_elf_sec *sec =
livepatch_elf_sec_by_name(elf, ELF_LIVEPATCH_XEN_DEPENDS);
@@ -498,13 +498,12 @@ static int check_xen_buildid(const struct livepatch_elf
*elf)
return -EINVAL;
}
- rc = xen_build_id(&id, &len);
- if ( rc )
+ if ( !len )
{
printk(XENLOG_ERR LIVEPATCH
"%s: unable to get running Xen build-id: %d\n",
elf->name, rc);
- return rc;
+ return -ENODATA;
}
if ( lp_id.len != len || memcmp(id, lp_id.p, len) )
@@ -1984,7 +1983,6 @@ static int build_id_dep(struct payload *payload, bool
internal)
{
const void *id = NULL;
unsigned int len = 0;
- int rc;
const char *name = "hypervisor";
ASSERT(payload->dep.len && payload->dep.p);
@@ -1992,9 +1990,10 @@ static int build_id_dep(struct payload *payload, bool
internal)
/* First time user is against hypervisor. */
if ( internal )
{
- rc = xen_build_id(&id, &len);
- if ( rc )
- return rc;
+ id = xen_build_id;
+ len = xen_build_id_len;
+ if ( !len )
+ return -ENODATA;
}
else
{
@@ -2249,14 +2248,12 @@ static const char *state2str(unsigned int state)
static void cf_check livepatch_printall(unsigned char key)
{
struct payload *data;
- const void *binary_id = NULL;
- unsigned int len = 0;
unsigned int i;
printk("'%c' pressed - Dumping all livepatch patches\n", key);
- if ( !xen_build_id(&binary_id, &len) )
- printk("build-id: %*phN\n", len, binary_id);
+ if ( xen_build_id_len )
+ printk("build-id: %*phN\n", xen_build_id_len, xen_build_id);
if ( !spin_trylock(&payload_lock) )
{
diff --git a/xen/common/version.c b/xen/common/version.c
index 84bd77e74653..553b97ba9b3c 100644
--- a/xen/common/version.c
+++ b/xen/common/version.c
@@ -94,8 +94,8 @@ const char *xen_build_info(void)
return build_info;
}
-static const void *build_id_p __read_mostly;
-static unsigned int build_id_len __read_mostly;
+const void *__ro_after_init xen_build_id;
+unsigned int __ro_after_init xen_build_id_len;
void print_version(void)
{
@@ -106,19 +106,8 @@ void print_version(void)
printk("Latest ChangeSet: %s\n", xen_changeset());
- if ( build_id_len )
- printk("build-id: %*phN\n", build_id_len, build_id_p);
-}
-
-int xen_build_id(const void **p, unsigned int *len)
-{
- if ( !build_id_len )
- return -ENODATA;
-
- *len = build_id_len;
- *p = build_id_p;
-
- return 0;
+ if ( xen_build_id_len )
+ printk("build-id: %*phN\n", xen_build_id_len, xen_build_id);
}
#ifdef BUILD_ID
@@ -193,7 +182,7 @@ void __init xen_build_init(void)
sz = (uintptr_t)__note_gnu_build_id_end - (uintptr_t)n;
- rc = xen_build_id_check(n, sz, &build_id_p, &build_id_len);
+ rc = xen_build_id_check(n, sz, &xen_build_id, &xen_build_id_len);
#ifdef CONFIG_X86
/*
@@ -219,8 +208,8 @@ void __init xen_build_init(void)
if ( info->cv_signature == CVINFO_PDB70_CVSIGNATURE )
{
- build_id_p = info->signature;
- build_id_len = sizeof(info->signature);
+ xen_build_id = info->signature;
+ xen_build_id_len = sizeof(info->signature);
rc = 0;
}
}
diff --git a/xen/include/xen/version.h b/xen/include/xen/version.h
index 4856ad1b446d..6f5d9c956054 100644
--- a/xen/include/xen/version.h
+++ b/xen/include/xen/version.h
@@ -17,10 +17,12 @@ const char *xen_changeset(void);
const char *xen_banner(void);
const char *xen_deny(void);
const char *xen_build_info(void);
-int xen_build_id(const void **p, unsigned int *len);
extern char xen_cap_info[128];
+extern const void *xen_build_id;
+extern unsigned int xen_build_id_len; /* 0 -> No build id. */
+
#ifdef BUILD_ID
void xen_build_init(void);
int xen_build_id_check(const Elf_Note *n, unsigned int n_sz,
--
2.39.5
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