Patchwork cpu_physical_memory_write_rom() needs to do TB invalidates

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Submitter David Gibson
Date Sept. 3, 2012, 12:58 a.m.
Message ID <1346633908-31386-1-git-send-email-david@gibson.dropbear.id.au>
Download mbox | patch
Permalink /patch/181278/
State New
Headers show

Comments

David Gibson - Sept. 3, 2012, 12:58 a.m.
cpu_physical_memory_write_rom(), despite the name, can also be used to
write images into RAM - and will often be used that way if the machine
uses load_image_targphys() into RAM addresses.

However, cpu_physical_memory_write_rom(), unlike
cpu_physical_memory_rw() doesn't invalidate any cached TBs which might
be affected by the region written.

This was breaking reset (under full emu) on the pseries machine - we loaded
our firmware image into RAM, and while executing it rewrite the code at
the entry point (correctly causing a TB invalidate/refresh).  When we
reset the firmware image was reloaded, but the TB from the rewrite was
still active and caused us to get an illegal instruction trap.

This patch fixes the bug by duplicating the tb invalidate code from
cpu_physical_memory_rw() in cpu_physical_memory_write_rom().

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 exec.c |    7 +++++++
 1 file changed, 7 insertions(+)

I've sent this before, and there was some discussion about the
details, but as far as I can tell the conclusion was that this patch
was as good as any, at least for fixing the existing bug in 1.2 /
stable.  However, it still hasn't been merged.

Please apply for stable as well as mainline.

Patch

diff --git a/exec.c b/exec.c
index 5834766..eff40d7 100644
--- a/exec.c
+++ b/exec.c
@@ -3523,6 +3523,13 @@  void cpu_physical_memory_write_rom(target_phys_addr_t addr,
             /* ROM/RAM case */
             ptr = qemu_get_ram_ptr(addr1);
             memcpy(ptr, buf, l);
+            if (!cpu_physical_memory_is_dirty(addr1)) {
+                /* invalidate code */
+                tb_invalidate_phys_page_range(addr1, addr1 + l, 0);
+                /* set dirty bit */
+                cpu_physical_memory_set_dirty_flags(
+                    addr1, (0xff & ~CODE_DIRTY_FLAG));
+            }
             qemu_put_ram_ptr(ptr);
         }
         len -= l;