From: Julian Seward <jseward@acm.org>
Date: Fri, 25 Feb 2005 02:45:39 +0000 (+0000)
Subject: On AMD64 it's valid to access up to 128 bytes below %rsp.  Or to be
X-Git-Tag: svn/VALGRIND_3_0_0~1066
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2cfb6bc855b07248db0d6c9763d27b95314be81e;p=thirdparty%2Fvalgrind.git

On AMD64 it's valid to access up to 128 bytes below %rsp.  Or to be
more accurate, on the amd64-linux ABI that is allowable.  Anyway,
parameterise the signal handler so it isn't confused by such accesses.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@3252
---

diff --git a/coregrind/amd64/core_arch.h b/coregrind/amd64/core_arch.h
index c7084497e6..16aaf37a4c 100644
--- a/coregrind/amd64/core_arch.h
+++ b/coregrind/amd64/core_arch.h
@@ -77,6 +77,10 @@
    asm("movq %%rbp, %0" : "=r" (lval));      \
 } while (0)
 
+// On AMD64, it's ok to access up to 128 bytes below %rsp.
+// The signal handler needs to know this.
+#define ARCH_STACK_REDZONE_SIZE 128
+
 /* ---------------------------------------------------------------------
    Architecture-specific part of a ThreadState
    ------------------------------------------------------------------ */
diff --git a/coregrind/vg_signals.c b/coregrind/vg_signals.c
index a46cdd3ef7..bebdaa5d6a 100644
--- a/coregrind/vg_signals.c
+++ b/coregrind/vg_signals.c
@@ -1781,17 +1781,17 @@ void vg_sync_signalhandler ( Int sigNo, vki_siginfo_t *info, struct vki_ucontext
 			 VG_(shadow_base), VG_(shadow_end));
       }
 
-      if (info->si_code == 1		&&	/* SEGV_MAPERR */
-	  seg != NULL                   &&
-	  fault >= esp			&&
-	  fault < seg->addr		&&
+      if (info->si_code == 1                        && /* SEGV_MAPERR */
+	  seg != NULL                               &&
+	  fault >= (esp	- ARCH_STACK_REDZONE_SIZE)  &&
+	  fault < seg->addr                         &&
 	  (seg->flags & SF_GROWDOWN)) {
 	 /* If the fault address is above esp but below the current known
 	    stack segment base, and it was a fault because there was
 	    nothing mapped there (as opposed to a permissions fault),
 	    then extend the stack segment. 
 	 */
-	 Addr base = PGROUNDDN(esp);
+	 Addr base = PGROUNDDN(esp - ARCH_STACK_REDZONE_SIZE);
          if (seg->len + (seg->addr - base) <= VG_(threads)[tid].stack_size &&
              (void*)-1 != VG_(mmap)((Char *)base, seg->addr - base,
                               VKI_PROT_READ|VKI_PROT_WRITE|VKI_PROT_EXEC,
diff --git a/coregrind/x86/core_arch.h b/coregrind/x86/core_arch.h
index 471f15f750..9feb3a544d 100644
--- a/coregrind/x86/core_arch.h
+++ b/coregrind/x86/core_arch.h
@@ -77,6 +77,10 @@
    asm("movl %%ebp, %0" : "=r" (ebp));       \
 } while (0)
 
+// On X86, any access below %esp is illegal.
+// The signal handler needs to know this.
+#define ARCH_STACK_REDZONE_SIZE 0
+
 /* ---------------------------------------------------------------------
    Architecture-specific part of a ThreadState
    ------------------------------------------------------------------ */