[xen master] libxc: remove / adjust xc_get_cpufreq_para()'s BUILD_BUG_ON()s

[patchbot@xxxxxxx]

commit 43dab6e7eff717a279b9e6bdf493f9a0fe20f39a
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Aug 23 16:14:10 2023 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Aug 23 16:14:10 2023 +0200

    libxc: remove / adjust xc_get_cpufreq_para()'s BUILD_BUG_ON()s
    
    The full structures cannot match in layout, as soon as a 32-bit tool
    stack build comes into play. But it also doesn't need to; the part of
    the layouts that needs to match is merely the union that we memcpy()
    from the sysctl structure to the xc one. Keep (in adjusted form) only
    the relevant ones.
    
    Since the whole block needs touching anyway, move it closer to the
    respective memcpy() and use a wrapper macro to limit verbosity. Also
    tidy the full-size-check there.
    
    Fixes: 2381dfab083f ("xen/sysctl: Nest cpufreq scaling options")
    Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
    Reviewed-by: Jason Andryuk <jandryuk@xxxxxxxxx>
---
 tools/libs/ctrl/xc_pm.c | 62 ++++++++++++++++---------------------------------
 1 file changed, 20 insertions(+), 42 deletions(-)

diff --git a/tools/libs/ctrl/xc_pm.c b/tools/libs/ctrl/xc_pm.c
index 6157f4e3d4..b20b675280 100644
--- a/tools/libs/ctrl/xc_pm.c
+++ b/tools/libs/ctrl/xc_pm.c
@@ -248,45 +248,6 @@ int xc_get_cpufreq_para(xc_interface *xch, int cpuid,
     sys_para->freq_num = user_para->freq_num;
     sys_para->gov_num  = user_para->gov_num;
 
-    /* Sanity check struct layout */
-    BUILD_BUG_ON(sizeof(*user_para) != sizeof(*sys_para));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), cpu_num) !=
-                 offsetof(typeof(*sys_para),  cpu_num));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), freq_num) !=
-                 offsetof(typeof(*sys_para),  freq_num));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), gov_num) !=
-                 offsetof(typeof(*sys_para),  gov_num));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), affected_cpus) !=
-                 offsetof(typeof(*sys_para),  affected_cpus));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), scaling_available_frequencies) !=
-                 offsetof(typeof(*sys_para),  scaling_available_frequencies));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), scaling_available_governors) !=
-                 offsetof(typeof(*sys_para),  scaling_available_governors));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), scaling_driver) !=
-                 offsetof(typeof(*sys_para),  scaling_driver));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), cpuinfo_cur_freq) !=
-                 offsetof(typeof(*sys_para),  cpuinfo_cur_freq));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), cpuinfo_max_freq) !=
-                 offsetof(typeof(*sys_para),  cpuinfo_max_freq));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), cpuinfo_min_freq) !=
-                 offsetof(typeof(*sys_para),  cpuinfo_min_freq));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), u.s.scaling_cur_freq) !=
-                 offsetof(typeof(*sys_para),  u.s.scaling_cur_freq));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), u.s.scaling_governor) !=
-                 offsetof(typeof(*sys_para),  u.s.scaling_governor));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), u.s.scaling_max_freq) !=
-                 offsetof(typeof(*sys_para),  u.s.scaling_max_freq));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), u.s.scaling_min_freq) !=
-                 offsetof(typeof(*sys_para),  u.s.scaling_min_freq));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), u.s.u.userspace) !=
-                 offsetof(typeof(*sys_para),  u.s.u.userspace));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), u.s.u.ondemand) !=
-                 offsetof(typeof(*sys_para),  u.s.u.ondemand));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), u.cppc_para) !=
-                 offsetof(typeof(*sys_para),  u.cppc_para));
-    BUILD_BUG_ON(offsetof(typeof(*user_para), turbo_enabled) !=
-                 offsetof(typeof(*sys_para),  turbo_enabled));
-
     ret = xc_sysctl(xch, &sysctl);
     if ( ret )
     {
@@ -312,9 +273,26 @@ int xc_get_cpufreq_para(xc_interface *xch, int cpuid,
         memcpy(user_para->scaling_driver,
                 sys_para->scaling_driver, CPUFREQ_NAME_LEN);
 
-        /* copy to user_para no matter what cpufreq driver/governor */
-        BUILD_BUG_ON(sizeof(((struct xc_get_cpufreq_para *)0)->u) !=
-                    sizeof(((struct xen_get_cpufreq_para *)0)->u));
+        /*
+         * Copy to user_para no matter what cpufreq driver/governor.
+         *
+         * First sanity check layout of the union subject to memcpy() below.
+         */
+        BUILD_BUG_ON(sizeof(user_para->u) != sizeof(sys_para->u));
+
+#define CHK_FIELD(fld) \
+        BUILD_BUG_ON(offsetof(typeof(user_para->u), fld) != \
+                     offsetof(typeof(sys_para->u),  fld))
+
+        CHK_FIELD(s.scaling_cur_freq);
+        CHK_FIELD(s.scaling_governor);
+        CHK_FIELD(s.scaling_max_freq);
+        CHK_FIELD(s.scaling_min_freq);
+        CHK_FIELD(s.u.userspace);
+        CHK_FIELD(s.u.ondemand);
+        CHK_FIELD(cppc_para);
+
+#undef CHK_FIELD
 
         memcpy(&user_para->u, &sys_para->u, sizeof(sys_para->u));
     }
--
generated by git-patchbot for /home/xen/git/xen.git#master