WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] [PATCH] xen: ioapic: avoid gcc 4.6 warnings about uninitiali

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] [PATCH] xen: ioapic: avoid gcc 4.6 warnings about uninitialised variables
From: Ian Campbell <ian.campbell@xxxxxxxxxx>
Date: Mon, 9 May 2011 11:43:40 +0100
Cc: 625438@xxxxxxxxxxxxxxx
Delivery-date: Mon, 09 May 2011 03:44:39 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mercurial-patchbomb/1.8.1
# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1304937815 -3600
# Node ID 35abcbcdf8bcabab6e0bbd929f69b613e167edfd
# Parent  4b0692880dfa557d4e1537c7a58c412c1286a416
xen: ioapic: avoid gcc 4.6 warnings about uninitialised variables

gcc 4.6 complains:
        io_apic.c: In function 'restore_IO_APIC_setup':
        
/build/user-xen_4.1.0-3-amd64-zSon7K/xen-4.1.0/debian/build/build-hypervisor_amd64_amd64/xen/include/asm/io_apic.h:150:26:
 error: '*((void *)&entry+4)' may be used uninitialized in this function 
[-Werror=uninitialized]
        io_apic.c:221:32: note: '*((void *)&entry+4)' was declared here
        
/build/user-xen_4.1.0-3-amd64-zSon7K/xen-4.1.0/debian/build/build-hypervisor_amd64_amd64/xen/include/asm/io_apic.h:150:26:
 error: 'entry' may be used uninitialized in this function 
[-Werror=uninitialized]
        io_apic.c:221:32: note: 'entry' was declared here
        cc1: all warnings being treated as errors

Add functions to read/write an entire IO APIC entry using an explicit
union to allow gcc to spot the initialisation.

Reported as Debian bug #625438, thanks to Matthias Klose.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

diff -r 4b0692880dfa -r 35abcbcdf8bc xen/arch/x86/io_apic.c
--- a/xen/arch/x86/io_apic.c    Thu May 05 17:40:34 2011 +0100
+++ b/xen/arch/x86/io_apic.c    Mon May 09 11:43:35 2011 +0100
@@ -156,6 +156,52 @@ nomem:
     return 0;
 }
 
+union entry_union {
+    struct { u32 w1, w2; };
+    struct IO_APIC_route_entry entry;
+};
+
+static struct IO_APIC_route_entry __ioapic_read_entry(int apic, int pin, int 
raw)
+{
+    unsigned int (*read)(unsigned int, unsigned int)
+        = raw ? __io_apic_read : io_apic_read;
+    union entry_union eu;
+    eu.w1 = (*read)(apic, 0x10 + 2 * pin);
+    eu.w2 = (*read)(apic, 0x11 + 2 * pin);
+    return eu.entry;
+}
+
+static struct IO_APIC_route_entry ioapic_read_entry(int apic, int pin, int raw)
+{
+    struct IO_APIC_route_entry entry;
+    unsigned long flags;
+
+    spin_lock_irqsave(&ioapic_lock, flags);
+    entry = __ioapic_read_entry(apic, pin, raw);
+    spin_unlock_irqrestore(&ioapic_lock, flags);
+    return entry;
+}
+
+static void
+__ioapic_write_entry(int apic, int pin, int raw, struct IO_APIC_route_entry e)
+{
+    void (*write)(unsigned int, unsigned int, unsigned int)
+        = raw ? __io_apic_write : io_apic_write;
+    union entry_union eu = {{0, 0}};
+
+    eu.entry = e;
+    (*write)(apic, 0x11 + 2*pin, eu.w2);
+    (*write)(apic, 0x10 + 2*pin, eu.w1);
+}
+
+static void ioapic_write_entry(int apic, int pin, int raw, struct 
IO_APIC_route_entry e)
+{
+    unsigned long flags;
+    spin_lock_irqsave(&ioapic_lock, flags);
+    __ioapic_write_entry(apic, pin, raw, e);
+    spin_unlock_irqrestore(&ioapic_lock, flags);
+}
+
 /*
  * Saves all the IO-APIC RTE's
  */
@@ -170,12 +216,8 @@ int save_IO_APIC_setup(struct IO_APIC_ro
         if (!ioapic_entries[apic])
             return -ENOMEM;
 
-        for (pin = 0; pin < nr_ioapic_registers[apic]; pin++) {
-            *(((int *)&ioapic_entries[apic][pin])+0) =
-                __io_apic_read(apic, 0x10+pin*2);
-            *(((int *)&ioapic_entries[apic][pin])+1) =
-                __io_apic_read(apic, 0x11+pin*2);
-        }
+        for (pin = 0; pin < nr_ioapic_registers[apic]; pin++)
+           ioapic_entries[apic][pin] = __ioapic_read_entry(apic, pin, 1);
     }
 
     return 0;
@@ -197,16 +239,12 @@ void mask_IO_APIC_setup(struct IO_APIC_r
 
         for (pin = 0; pin < nr_ioapic_registers[apic]; pin++) {
             struct IO_APIC_route_entry entry;
-            unsigned long flags;
 
             entry = ioapic_entries[apic][pin];
             if (!entry.mask) {
                 entry.mask = 1;
 
-                spin_lock_irqsave(&ioapic_lock, flags);
-                __io_apic_write(apic, 0x11+2*pin, *(((int *)&entry)+1));
-                __io_apic_write(apic, 0x10+2*pin, *(((int *)&entry)+0));
-                spin_unlock_irqrestore(&ioapic_lock, flags);
+                ioapic_write_entry(apic, pin, 1, entry);
             }
         }
     }
@@ -218,8 +256,6 @@ void mask_IO_APIC_setup(struct IO_APIC_r
 int restore_IO_APIC_setup(struct IO_APIC_route_entry **ioapic_entries)
 {
     int apic, pin;
-    unsigned long flags;
-    struct IO_APIC_route_entry entry;
 
     if (!ioapic_entries)
         return -ENOMEM;
@@ -229,11 +265,7 @@ int restore_IO_APIC_setup(struct IO_APIC
             return -ENOMEM;
 
         for (pin = 0; pin < nr_ioapic_registers[apic]; pin++)
-            entry = ioapic_entries[apic][pin];
-            spin_lock_irqsave(&ioapic_lock, flags);
-            __io_apic_write(apic, 0x11+2*pin, *(((int *)&entry)+1));
-            __io_apic_write(apic, 0x10+2*pin, *(((int *)&entry)+0));
-            spin_unlock_irqrestore(&ioapic_lock, flags);
+           ioapic_write_entry(apic, pin, 1, ioapic_entries[apic][pin]);
     }
 
     return 0;
@@ -338,18 +370,10 @@ static void eoi_IO_APIC_irq(unsigned int
 #define clear_IO_APIC_pin_raw(a,p) __clear_IO_APIC_pin(a,p,1)
 static void __clear_IO_APIC_pin(unsigned int apic, unsigned int pin, int raw)
 {
-    unsigned int (*read)(unsigned int, unsigned int)
-        = raw ? __io_apic_read : io_apic_read;
-    void (*write)(unsigned int, unsigned int, unsigned int)
-        = raw ? __io_apic_write : io_apic_write;
     struct IO_APIC_route_entry entry;
-    unsigned long flags;
-    
+
     /* Check delivery_mode to be sure we're not clearing an SMI pin */
-    spin_lock_irqsave(&ioapic_lock, flags);
-    *(((int*)&entry) + 0) = (*read)(apic, 0x10 + 2 * pin);
-    *(((int*)&entry) + 1) = (*read)(apic, 0x11 + 2 * pin);
-    spin_unlock_irqrestore(&ioapic_lock, flags);
+    entry = ioapic_read_entry(apic, pin, raw);
     if (entry.delivery_mode == dest_SMI)
         return;
 
@@ -358,10 +382,7 @@ static void __clear_IO_APIC_pin(unsigned
      */
     memset(&entry, 0, sizeof(entry));
     entry.mask = 1;
-    spin_lock_irqsave(&ioapic_lock, flags);
-    (*write)(apic, 0x10 + 2 * pin, *(((int *)&entry) + 0));
-    (*write)(apic, 0x11 + 2 * pin, *(((int *)&entry) + 1));
-    spin_unlock_irqrestore(&ioapic_lock, flags);
+    ioapic_write_entry(apic, pin, raw, entry);
 }
 
 static void clear_IO_APIC (void)
@@ -990,11 +1011,10 @@ static void __init setup_IO_APIC_irqs(vo
             SET_DEST(entry.dest.dest32, entry.dest.logical.logical_dest,
                      cpu_mask_to_apicid(&cfg->cpu_mask));
             spin_lock_irqsave(&ioapic_lock, flags);
-            io_apic_write(apic, 0x11+2*pin, *(((int *)&entry)+1));
-            io_apic_write(apic, 0x10+2*pin, *(((int *)&entry)+0));
+            __ioapic_write_entry(apic, pin, 0, entry);
             set_native_irq_info(irq, TARGET_CPUS);
             spin_unlock_irqrestore(&ioapic_lock, flags);
-       }
+        }
     }
 
     if (!first_notcon)
@@ -1007,7 +1027,6 @@ static void __init setup_IO_APIC_irqs(vo
 static void __init setup_ExtINT_IRQ0_pin(unsigned int apic, unsigned int pin, 
int vector)
 {
     struct IO_APIC_route_entry entry;
-    unsigned long flags;
 
     memset(&entry,0,sizeof(entry));
 
@@ -1038,10 +1057,7 @@ static void __init setup_ExtINT_IRQ0_pin
     /*
      * Add it to the IO-APIC irq-routing table:
      */
-    spin_lock_irqsave(&ioapic_lock, flags);
-    io_apic_write(apic, 0x11+2*pin, *(((int *)&entry)+1));
-    io_apic_write(apic, 0x10+2*pin, *(((int *)&entry)+0));
-    spin_unlock_irqrestore(&ioapic_lock, flags);
+    ioapic_write_entry(apic, pin, 0, entry);
 
     enable_8259A_irq(0);
 }
@@ -1148,10 +1164,7 @@ static void /*__init*/ __print_IO_APIC(v
        for (i = 0; i <= reg_01.bits.entries; i++) {
             struct IO_APIC_route_entry entry;
 
-            spin_lock_irqsave(&ioapic_lock, flags);
-            *(((int *)&entry)+0) = io_apic_read(apic, 0x10+i*2);
-            *(((int *)&entry)+1) = io_apic_read(apic, 0x11+i*2);
-            spin_unlock_irqrestore(&ioapic_lock, flags);
+            entry = ioapic_read_entry(apic, i, 0);
 
             printk(KERN_DEBUG " %02x %03X %02X  ",
                    i,
@@ -1212,7 +1225,6 @@ static void __init enable_IO_APIC(void)
 {
     int i8259_apic, i8259_pin;
     int i, apic;
-    unsigned long flags;
 
     /* Initialise dynamic irq_2_pin free list. */
     irq_2_pin = xmalloc_array(struct irq_pin_list, PIN_MAP_SIZE);
@@ -1227,12 +1239,7 @@ static void __init enable_IO_APIC(void)
         int pin;
         /* See if any of the pins is in ExtINT mode */
         for (pin = 0; pin < nr_ioapic_registers[apic]; pin++) {
-            struct IO_APIC_route_entry entry;
-            spin_lock_irqsave(&ioapic_lock, flags);
-            *(((int *)&entry) + 0) = io_apic_read(apic, 0x10 + 2 * pin);
-            *(((int *)&entry) + 1) = io_apic_read(apic, 0x11 + 2 * pin);
-            spin_unlock_irqrestore(&ioapic_lock, flags);
-
+            struct IO_APIC_route_entry entry = ioapic_read_entry(apic, pin, 0);
 
             /* If the interrupt line is enabled and in ExtInt mode
              * I have found the pin where the i8259 is connected.
@@ -1288,7 +1295,6 @@ void disable_IO_APIC(void)
      */
     if (ioapic_i8259.pin != -1) {
         struct IO_APIC_route_entry entry;
-        unsigned long flags;
 
         memset(&entry, 0, sizeof(entry));
         entry.mask            = 0; /* Enabled */
@@ -1305,12 +1311,7 @@ void disable_IO_APIC(void)
         /*
          * Add it to the IO-APIC irq-routing table:
          */
-        spin_lock_irqsave(&ioapic_lock, flags);
-        io_apic_write(ioapic_i8259.apic, 0x11+2*ioapic_i8259.pin,
-                      *(((int *)&entry)+1));
-        io_apic_write(ioapic_i8259.apic, 0x10+2*ioapic_i8259.pin,
-                      *(((int *)&entry)+0));
-        spin_unlock_irqrestore(&ioapic_lock, flags);
+        ioapic_write_entry(ioapic_i8259.apic, ioapic_i8259.pin, 0, entry);
     }
     disconnect_bsp_APIC(ioapic_i8259.pin != -1);
 }
@@ -1838,17 +1839,13 @@ static void __init unlock_ExtINT_logic(v
     int apic, pin, i;
     struct IO_APIC_route_entry entry0, entry1;
     unsigned char save_control, save_freq_select;
-    unsigned long flags;
 
     pin = find_isa_irq_pin(8, mp_INT);
     apic = find_isa_irq_apic(8, mp_INT);
     if (pin == -1)
         return;
 
-    spin_lock_irqsave(&ioapic_lock, flags);
-    *(((int *)&entry0) + 1) = io_apic_read(apic, 0x11 + 2 * pin);
-    *(((int *)&entry0) + 0) = io_apic_read(apic, 0x10 + 2 * pin);
-    spin_unlock_irqrestore(&ioapic_lock, flags);
+    entry0 = ioapic_read_entry(apic, pin, 0);
     clear_IO_APIC_pin(apic, pin);
 
     memset(&entry1, 0, sizeof(entry1));
@@ -1862,10 +1859,7 @@ static void __init unlock_ExtINT_logic(v
     entry1.trigger = 0;
     entry1.vector = 0;
 
-    spin_lock_irqsave(&ioapic_lock, flags);
-    io_apic_write(apic, 0x11 + 2 * pin, *(((int *)&entry1) + 1));
-    io_apic_write(apic, 0x10 + 2 * pin, *(((int *)&entry1) + 0));
-    spin_unlock_irqrestore(&ioapic_lock, flags);
+    ioapic_write_entry(apic, pin, 0, entry1);
 
     save_control = CMOS_READ(RTC_CONTROL);
     save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
@@ -1884,10 +1878,7 @@ static void __init unlock_ExtINT_logic(v
     CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
     clear_IO_APIC_pin(apic, pin);
 
-    spin_lock_irqsave(&ioapic_lock, flags);
-    io_apic_write(apic, 0x11 + 2 * pin, *(((int *)&entry0) + 1));
-    io_apic_write(apic, 0x10 + 2 * pin, *(((int *)&entry0) + 0));
-    spin_unlock_irqrestore(&ioapic_lock, flags);
+    ioapic_write_entry(apic, pin, 0, entry0);
 }
 
 /*
@@ -2262,8 +2253,7 @@ int io_apic_set_pci_routing (int ioapic,
         disable_8259A_irq(irq);
 
     spin_lock_irqsave(&ioapic_lock, flags);
-    io_apic_write(ioapic, 0x11+2*pin, *(((int *)&entry)+1));
-    io_apic_write(ioapic, 0x10+2*pin, *(((int *)&entry)+0));
+    __ioapic_write_entry(ioapic, pin, 0, entry);
     set_native_irq_info(irq, TARGET_CPUS);
     spin_unlock(&ioapic_lock);
 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel