[Bug middle-end/84095] [8 Regression] false-positive -Wrestrict warnings for memcpy within array

[arnd at linaro dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84095

--- Comment #5 from Arnd Bergmann <arnd at linaro dot org> ---
Here are some additional instances in the kernel. I'm currently trying to get a
reliable build first and haven't got a log of all the messages, but there are a
number of changes I did that are related, shutting up the -Wrestrict warning
(some may be -Warray-bounds).

Here are some false-positives:

--- a/arch/x86/oprofile/nmi_int.c
+++ b/arch/x86/oprofile/nmi_int.c
@@ -282,9 +282,7 @@ static void mux_clone(int cpu)
        if (!has_mux())
                return;

-       memcpy(per_cpu(cpu_msrs, cpu).multiplex,
-              per_cpu(cpu_msrs, 0).multiplex,
-              sizeof(struct op_msr) * model->num_virt_counters);
+       per_cpu(cpu_msrs, cpu).multiplex = per_cpu(cpu_msrs, 0).multiplex;
 }

 #else
@@ -463,6 +461,7 @@ static int nmi_setup(void)
                if (!cpu)
                        continue;

+#ifdef CONFIG_SMP
                memcpy(per_cpu(cpu_msrs, cpu).counters,
                       per_cpu(cpu_msrs, 0).counters,
                       sizeof(struct op_msr) * model->num_counters);
@@ -470,7 +469,7 @@ static int nmi_setup(void)
                memcpy(per_cpu(cpu_msrs, cpu).controls,
                       per_cpu(cpu_msrs, 0).controls,
                       sizeof(struct op_msr) * model->num_controls);
-
+#endif
                mux_clone(cpu);
        }
--- a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
+++ b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
@@ -1643,7 +1643,7 @@ static int cfg80211_rtw_scan(struct wiphy *wiphy
        spin_lock_bh(&pmlmepriv->lock);
        if (request->n_channels == 1) {
                for (i = 1;i<survey_times_for_one_ch;i++)
-                       memcpy(&ch[i], &ch[0], sizeof(struct
rtw_ieee80211_channel));
+                       ch[i] = ch[0];
                _status = rtw_sitesurvey_cmd(padapter, ssid,
RTW_SSID_SCAN_AMOUNT, ch, survey_times_for_one_ch);
        } else if (request->n_channels <= 4) {
                for (j =request->n_channels-1;j>= 0;j--)


This one was weird, I suspect my change is incorrect:

diff --git a/drivers/fmc/fmc-fakedev.c b/drivers/fmc/fmc-fakedev.c
index 941d0930969a..0d322380d952 100644
--- a/drivers/fmc/fmc-fakedev.c
+++ b/drivers/fmc/fmc-fakedev.c
@@ -305,7 +305,7 @@ static int ff_init(void)

        /* Replicate the default eeprom for the max number of mezzanines */
        for (i = 1; i < FF_MAX_MEZZANINES; i++)
-               memcpy(ff_eeimg[i], ff_eeimg[0], sizeof(ff_eeimg[0]));
+               memcpy(&ff_eeimg[i][0], &ff_eeimg[0][0], sizeof(ff_eeimg[0]));

        if (ff_nr_eeprom > ff_nr_dev)
                ff_nr_dev = ff_nr_eeprom;

This one seems to be a kernel bug:

--- a/kernel/debug/kdb/kdb_support.c
+++ b/kernel/debug/kdb/kdb_support.c
@@ -129,13 +129,13 @@ int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
                }
                if (i >= ARRAY_SIZE(kdb_name_table)) {
                        debug_kfree(kdb_name_table[0]);
-                       memcpy(kdb_name_table, kdb_name_table+1,
+                       memmove(kdb_name_table, kdb_name_table+1,
                               sizeof(kdb_name_table[0]) *
                               (ARRAY_SIZE(kdb_name_table)-1));
                } else {
                        debug_kfree(knt1);
                        knt1 = kdb_name_table[i];
-                       memcpy(kdb_name_table+i, kdb_name_table+i+1,
+                       memmove(kdb_name_table+i, kdb_name_table+i+1,
                               sizeof(kdb_name_table[0]) *
                               (ARRAY_SIZE(kdb_name_table)-i-1));
                }