[PULL,17/21] linux-user: fix segmentation fault passing with h2g(x) != x

Submitted by riku.voipio@linaro.org on July 23, 2013, 3:49 p.m.

Details

Message ID 732f9e89a1c737f738c445ff24929a1bc137d1a9.1374593203.git.riku.voipio@linaro.org
State New
Headers show

Commit Message

riku.voipio@linaro.org July 23, 2013, 3:49 p.m.
From: Alexander Graf <agraf@suse.de>

When forwarding a segmentation fault into the guest process, we were passing
the host's address directly into the guest process's signal descriptor.

That obviously confused the guest process, since it didn't know what to make
of the (usually 32-bit truncated) address. Passing in h2g(address) makes the
guest process a lot happier.

To make the code more obvious, introduce a h2g_nocheck() macro that does the
same as h2g(), but allows us to convert addresses that may be outside of guest
mapped range into the guest's view of address space.

This fixes java running in arm-linux-user for me.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
---
 include/exec/cpu-all.h | 8 ++++++--
 user-exec.c            | 4 ++++
 2 files changed, 10 insertions(+), 2 deletions(-)

Patch hide | download patch | download mbox

diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
index 5084202..f1cde97 100644
--- a/include/exec/cpu-all.h
+++ b/include/exec/cpu-all.h
@@ -209,11 +209,15 @@  extern unsigned long reserved_va;
 })
 #endif
 
-#define h2g(x) ({ \
+#define h2g_nocheck(x) ({ \
     unsigned long __ret = (unsigned long)(x) - GUEST_BASE; \
+    (abi_ulong)__ret; \
+})
+
+#define h2g(x) ({ \
     /* Check if given address fits target address space */ \
     assert(h2g_valid(x)); \
-    (abi_ulong)__ret; \
+    h2g_nocheck(x); \
 })
 
 #define saddr(x) g2h(x)
diff --git a/user-exec.c b/user-exec.c
index d45ca8e..82bfa66 100644
--- a/user-exec.c
+++ b/user-exec.c
@@ -95,6 +95,10 @@  static inline int handle_cpu_signal(uintptr_t pc, unsigned long address,
         return 1;
     }
 
+    /* Convert forcefully to guest address space, invalid addresses
+       are still valid segv ones */
+    address = h2g_nocheck(address);
+
     env = current_cpu->env_ptr;
     /* see if it is an MMU fault */
     ret = cpu_handle_mmu_fault(env, address, is_write, MMU_USER_IDX);