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* [Qemu-devel] [PATCH v2] exec.c: Fix subpage memory access to RAM MemoryRegion
@ 2011-11-30 15:26 Andreas Färber
  2011-12-01  9:29 ` Avi Kivity
                   ` (2 more replies)
  0 siblings, 3 replies; 13+ messages in thread
From: Andreas Färber @ 2011-11-30 15:26 UTC (permalink / raw)
  To: qemu-devel; +Cc: Andreas Färber, Gleb Natapov, Avi Kivity

Commit 95c318f5e1f88d7e5bcc6deac17330fd4806a2d3 (Fix segfault in mmio
subpage handling code.) prevented a segfault by making all subpage
registrations over an existing memory page perform an unassigned access.
Symptoms were writes not taking effect and reads returning zero.

Very small page sizes are not currently supported either,
so subpage memory areas cannot fully be avoided.

Therefore change the previous fix to use a new IO_MEM_SUBPAGE_RAM
instead of IO_MEM_UNASSIGNED. Suggested by Avi.

Signed-off-by: Andreas Färber <afaerber@suse.de>
Cc: Avi Kivity <avi@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
---
 cpu-common.h |    1 +
 exec.c       |   65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/cpu-common.h b/cpu-common.h
index c9878ba..3f45428 100644
--- a/cpu-common.h
+++ b/cpu-common.h
@@ -172,6 +172,7 @@ void cpu_physical_memory_write_rom(target_phys_addr_t addr,
 #define IO_MEM_ROM         (1 << IO_MEM_SHIFT) /* hardcoded offset */
 #define IO_MEM_UNASSIGNED  (2 << IO_MEM_SHIFT)
 #define IO_MEM_NOTDIRTY    (3 << IO_MEM_SHIFT)
+#define IO_MEM_SUBPAGE_RAM (4 << IO_MEM_SHIFT)
 
 /* Acts like a ROM when read and like a device when written.  */
 #define IO_MEM_ROMD        (1)
diff --git a/exec.c b/exec.c
index 6b92198..6c206ff 100644
--- a/exec.c
+++ b/exec.c
@@ -3570,6 +3570,63 @@ static CPUWriteMemoryFunc * const subpage_write[] = {
     &subpage_writel,
 };
 
+static uint32_t subpage_ram_readb(void *opaque, target_phys_addr_t addr)
+{
+    ram_addr_t raddr = addr;
+    void *ptr = qemu_get_ram_ptr(raddr);
+    return ldub_p(ptr);
+}
+
+static void subpage_ram_writeb(void *opaque, target_phys_addr_t addr,
+                               uint32_t value)
+{
+    ram_addr_t raddr = addr;
+    void *ptr = qemu_get_ram_ptr(raddr);
+    stb_p(ptr, value);
+}
+
+static uint32_t subpage_ram_readw(void *opaque, target_phys_addr_t addr)
+{
+    ram_addr_t raddr = addr;
+    void *ptr = qemu_get_ram_ptr(raddr);
+    return lduw_p(ptr);
+}
+
+static void subpage_ram_writew(void *opaque, target_phys_addr_t addr,
+                               uint32_t value)
+{
+    ram_addr_t raddr = addr;
+    void *ptr = qemu_get_ram_ptr(raddr);
+    stw_p(ptr, value);
+}
+
+static uint32_t subpage_ram_readl(void *opaque, target_phys_addr_t addr)
+{
+    ram_addr_t raddr = addr;
+    void *ptr = qemu_get_ram_ptr(raddr);
+    return ldl_p(ptr);
+}
+
+static void subpage_ram_writel(void *opaque, target_phys_addr_t addr,
+                               uint32_t value)
+{
+    ram_addr_t raddr = addr;
+    void *ptr = qemu_get_ram_ptr(raddr);
+    stl_p(ptr, value);
+}
+
+static CPUReadMemoryFunc * const subpage_ram_read[] = {
+    &subpage_ram_readb,
+    &subpage_ram_readw,
+    &subpage_ram_readl,
+};
+
+static CPUWriteMemoryFunc * const subpage_ram_write[] = {
+    &subpage_ram_writeb,
+    &subpage_ram_writew,
+    &subpage_ram_writel,
+};
+
 static int subpage_register (subpage_t *mmio, uint32_t start, uint32_t end,
                              ram_addr_t memory, ram_addr_t region_offset)
 {
@@ -3583,8 +3640,9 @@ static int subpage_register (subpage_t *mmio, uint32_t start, uint32_t end,
     printf("%s: %p start %08x end %08x idx %08x eidx %08x mem %ld\n", __func__,
            mmio, start, end, idx, eidx, memory);
 #endif
-    if ((memory & ~TARGET_PAGE_MASK) == IO_MEM_RAM)
-        memory = IO_MEM_UNASSIGNED;
+    if ((memory & ~TARGET_PAGE_MASK) == IO_MEM_RAM) {
+        memory = IO_MEM_SUBPAGE_RAM;
+    }
     memory = (memory >> IO_MEM_SHIFT) & (IO_MEM_NB_ENTRIES - 1);
     for (; idx <= eidx; idx++) {
         mmio->sub_io_index[idx] = memory;
@@ -3817,6 +3875,9 @@ static void io_mem_init(void)
     cpu_register_io_memory_fixed(IO_MEM_NOTDIRTY, error_mem_read,
                                  notdirty_mem_write, NULL,
                                  DEVICE_NATIVE_ENDIAN);
+    cpu_register_io_memory_fixed(IO_MEM_SUBPAGE_RAM, subpage_ram_read,
+                                 subpage_ram_write, NULL,
+                                 DEVICE_NATIVE_ENDIAN);
     for (i=0; i<5; i++)
         io_mem_used[i] = 1;
 
-- 
1.7.7

^ permalink raw reply related	[flat|nested] 13+ messages in thread
end of thread, other threads:[~2012-08-22 16:53 UTC | newest]

Thread overview: 13+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-11-30 15:26 [Qemu-devel] [PATCH v2] exec.c: Fix subpage memory access to RAM MemoryRegion Andreas Färber
2011-12-01  9:29 ` Avi Kivity
2011-12-01  9:37   ` Gleb Natapov
2011-12-01  9:41     ` Avi Kivity
2011-12-01  9:47       ` Gleb Natapov
2011-12-01  9:54         ` Avi Kivity
2011-12-01 10:06           ` Gleb Natapov
2011-12-01 17:18             ` Andreas Färber
2011-12-01 17:24               ` Avi Kivity
2011-12-09 12:32   ` Andreas Färber
2011-12-11  9:51 ` Avi Kivity
2011-12-15 18:09 ` Anthony Liguori
2012-08-22 16:53   ` Andreas Färber

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