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fix PointsToValidCall for some types of CALL instructions

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get a stack frame if we eg. "CALL NULL"
This commit is contained in:
Glenn Maynard
2004-04-10 20:18:49 +00:00
parent c3b3df6d69
commit 2cfb403220
1 changed files with 28 additions and 9 deletions
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stepmania/src/archutils/Unix/Backtrace.cpp
+28 -9
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@@ -184,13 +184,20 @@ struct StackFrame
const void *return_address;
};
/* Return true if the given stack pointer is in readable memory. */
/* Return true if the given pointer is in readable memory, and on the stack. */
bool IsOnStack( const void *p )
{
int val = find_address( p, g_ReadableBegin, g_ReadableEnd );
return val != -1 && (val == g_StackBlock1 || val == g_StackBlock2 );
}
/* Return true if the given pointer is in executable memory. */
bool IsExecutableAddress( const void *p )
{
int val = find_address( p, g_ExecutableBegin, g_ExecutableEnd );
return val != -1;
}
/* Return true if the given stack frame is in readable memory. */
bool IsReadableFrame( const StackFrame *frame )
{
@@ -242,15 +249,15 @@ static bool PointsToValidCall( const void *ptr )
return true;
// FF D0-D7 CALL reg32
if (len >= 2 && buf[-2] == '\xff' && (buf[-1]&0xF8) == '\xd0')
if (len >= 2 && buf[-2] == '\xff' && char(buf[-1]&0xF8) == '\xd0')
return true;
// FF 50-57 xx CALL [reg32+reg32*scale+disp8]
if (len >= 3 && buf[-3] == '\xff' && (buf[-2]&0xF8) == '\x50')
if (len >= 3 && buf[-3] == '\xff' && char(buf[-2]&0xF8) == '\x50')
return true;
// FF 90-97 xx xx xx xx xx CALL [reg32+reg32*scale+disp32]
if (len >= 7 && buf[-7] == '\xff' && (buf[-6]&0xF8) == '\x90')
if (len >= 7 && buf[-7] == '\xff' && char(buf[-6]&0xF8) == '\x90')
return true;
return false;
@@ -272,8 +279,7 @@ bool IsValidFrame( const StackFrame *frame )
return false;
/* The return address should be in a readable, executable page. */
int val = find_address( frame->return_address, g_ExecutableBegin, g_ExecutableEnd );
if( val == -1 )
if( !IsExecutableAddress( frame->return_address ) )
return false;
/* The return address should follow a CALL opcode. */
@@ -285,7 +291,7 @@ bool IsValidFrame( const StackFrame *frame )
/* This x86 backtracer attempts to walk the stack frames. If we come to a
* place that doesn't look like a valid frame, we'll look forward and try
* to find it again. */
* to find one again. */
static void do_backtrace( const void **buf, size_t size, const BacktraceContext *ctx )
{
/* Read /proc/pid/maps to find the address range of the stack. */
@@ -296,17 +302,30 @@ static void do_backtrace( const void **buf, size_t size, const BacktraceContext
g_StackBlock1 = find_address( ctx->esp, g_ReadableBegin, g_ReadableEnd );
g_StackBlock2 = find_address( SavedStackPointer, g_ReadableBegin, g_ReadableEnd );
/* If eip is valid, put it at the top of the backtrace. */
/* Put eip at the top of the backtrace. */
/* XXX: We want EIP even if it's not valid, but we can't put NULL on the
* list, since it's NULL-terminated. Hmm. */
unsigned i=0;
if( i < size-1 && ctx->eip ) // -1 for NULL
buf[i++] = ctx->eip;
/* If we did a CALL to an invalid address (eg. call a NULL callback), then
* we won't have a stack frame for the function that called it (since the
* stack frame is set up by the called function), but if esp hasn't been
* changed after the CALL, the return address will be esp[0]. Grab it. */
if( IsOnStack( ctx->esp ) )
{
const void *p = ((const void **) ctx->esp)[0];
if( IsExecutableAddress( p ) && PointsToValidCall( p ) && i < size-1 ) // -1 for NULL
buf[i++] = p;
}
/* ebp is usually the frame pointer. */
const StackFrame *frame = (StackFrame *) ctx->ebp;
/* If ebp doesn't point to a valid stack frame, we're probably in
* -fomit-frame-pointer code. Ignore it; use esp instead. It probably
* won't * point to a stack frame, but it should at least give us a starting
* won't point to a stack frame, but it should at least give us a starting
* point in the stack. */
if( !IsValidFrame( frame ) )
frame = (StackFrame *) ctx->esp;