x86: Fix implicit stack addressing in 64-bit mode

When in 64-bit mode, if the stack is accessed implicitly by an instruction,
the alternate address prefix should be ignored if present.

This patch adds an extra flag to the ldstop which signifies when the
address override should be ignored. Then, for all of the affected
instructions, this patch adds two options to the ld and st opcode to
use the current stack addressing mode for all addresses and to ignore the
AddressSizeFlagBit.
Finally, this patch updates the x86 TLB to not truncate the address if it
is in 64-bit mode and the IgnoreAddrSizeFlagBit is set.

This fixes a problem when calling __libc_start_main with a binary that
is linked with a recent version of ld. This version of ld uses the
address override prefix (0x67) on the call instruction instead of a nop.

Note: This has not been tested in compatibility mode and only the call
instruction with the address override prefix has been tested.

See [1] page 9 (pdf page 45)

For instructions that are affected see [1] page 519 (pdf page 555).

[1] http://support.amd.com/TechDocs/24594.pdf

Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>

src/arch/x86/isa/insts/general_purpose/control_transfer/call.py

@@ -45,7 +45,7 @@ def macroop CALL_NEAR_I
     limm t1, imm
     rdip t7
     # Check target of call
-    st t7, ss, [0, t0, rsp], "-env.dataSize"
+    st_stack t7, ss, [0, t0, rsp], "-env.dataSize"
     subi rsp, rsp, ssz
     wrip t7, t1
 };
@@ -58,7 +58,7 @@ def macroop CALL_NEAR_R
 
     rdip t1
     # Check target of call
-    st t1, ss, [0, t0, rsp], "-env.dataSize"
+    st_stack t1, ss, [0, t0, rsp], "-env.dataSize"
     subi rsp, rsp, ssz
     wripi reg, 0
 };

src/arch/x86/isa/insts/general_purpose/data_transfer/stack_operations.py

@@ -40,7 +40,7 @@ def macroop POP_R {
     # Make the default data size of pops 64 bits in 64 bit mode
     .adjust_env oszIn64Override
 
-    ld t1, ss, [1, t0, rsp], dataSize=ssz
+    ld_stack t1, ss, [1, t0, rsp], dataSize=ssz
     addi rsp, rsp, ssz, dataSize=asz
     mov reg, reg, t1
 };
@@ -49,7 +49,7 @@ def macroop POP_M {
     # Make the default data size of pops 64 bits in 64 bit mode
     .adjust_env oszIn64Override
 
-    ld t1, ss, [1, t0, rsp], dataSize=ssz
+    ld_stack t1, ss, [1, t0, rsp], dataSize=ssz
     cda seg, sib, disp, dataSize=ssz
     addi rsp, rsp, ssz, dataSize=asz
     st t1, seg, sib, disp, dataSize=ssz
@@ -70,7 +70,7 @@ def macroop PUSH_R {
     # Make the default data size of pops 64 bits in 64 bit mode
     .adjust_env oszIn64Override
 
-    st reg, ss, [1, t0, rsp], "-env.stackSize", dataSize=ssz
+    st_stack reg, ss, [1, t0, rsp], "-env.stackSize", dataSize=ssz
     subi rsp, rsp, ssz
 };
 
@@ -79,7 +79,7 @@ def macroop PUSH_I {
     .adjust_env oszIn64Override
 
     limm t1, imm
-    st t1, ss, [1, t0, rsp], "-env.stackSize", dataSize=ssz
+    st_stack t1, ss, [1, t0, rsp], "-env.stackSize", dataSize=ssz
     subi rsp, rsp, ssz
 };
 
@@ -138,7 +138,7 @@ def macroop LEAVE {
     .adjust_env oszIn64Override
 
     mov t1, t1, rbp, dataSize=ssz
-    ld rbp, ss, [1, t0, t1], dataSize=ssz
+    ld_stack rbp, ss, [1, t0, t1], dataSize=ssz
     mov rsp, rsp, t1, dataSize=ssz
     addi rsp, rsp, ssz, dataSize=ssz
 };
@@ -156,7 +156,7 @@ def macroop ENTER_I_I {
     # t1 is now the masked nesting level, and t2 is the amount of storage.
 
     # Push rbp.
-    st rbp, ss, [1, t0, rsp], "-env.dataSize"
+    st_stack rbp, ss, [1, t0, rsp], "-env.dataSize"
     subi rsp, rsp, ssz
 
     # Save the stack pointer for later
@@ -172,8 +172,8 @@ def macroop ENTER_I_I {
 
     limm t4, "ULL(-1)", dataSize=8
 topOfLoop:
-    ld t5, ss, [dsz, t4, rbp]
+    ld_stack t5, ss, [dsz, t4, rbp]
-    st t5, ss, [1, t0, rsp], "-env.dataSize"
+    st_stack t5, ss, [1, t0, rsp], "-env.dataSize"
     subi rsp, rsp, ssz
 
     # If we're not done yet, loop
@@ -183,7 +183,7 @@ topOfLoop:
 
 bottomOfLoop:
     # Push the old rbp onto the stack
-    st t6, ss, [1, t0, rsp], "-env.dataSize"
+    st_stack t6, ss, [1, t0, rsp], "-env.dataSize"
     subi rsp, rsp, ssz
 
 skipLoop:

src/arch/x86/isa/microops/ldstop.isa

@@ -315,7 +315,8 @@ def template MicroLdStSplitOpConstructor {{
 let {{
     class LdStOp(X86Microop):
         def __init__(self, data, segment, addr, disp,
-                dataSize, addressSize, baseFlags, atCPL0, prefetch, nonSpec):
+                dataSize, addressSize, baseFlags, atCPL0, prefetch, nonSpec,
+                implicitStack):
             self.data = data
             [self.scale, self.index, self.base] = addr
             self.disp = disp
@@ -331,6 +332,9 @@ let {{
                 self.instFlags += " | (1ULL << StaticInst::IsDataPrefetch)"
             if nonSpec:
                 self.instFlags += " | (1ULL << StaticInst::IsNonSpeculative)"
+            # For implicit stack operations, we should use *not* use the
+            # alternative addressing mode for loads/stores if the prefix is set
+            if not implicitStack:
                 self.memFlags += " | (machInst.legacy.addr ? " + \
                                  "(AddrSizeFlagBit << FlagShift) : 0)"
 
@@ -351,7 +355,8 @@ let {{
 
     class BigLdStOp(X86Microop):
         def __init__(self, data, segment, addr, disp,
-                dataSize, addressSize, baseFlags, atCPL0, prefetch, nonSpec):
+                dataSize, addressSize, baseFlags, atCPL0, prefetch, nonSpec,
+                implicitStack):
             self.data = data
             [self.scale, self.index, self.base] = addr
             self.disp = disp
@@ -367,6 +372,9 @@ let {{
                 self.instFlags += " | (1ULL << StaticInst::IsDataPrefetch)"
             if nonSpec:
                 self.instFlags += " | (1ULL << StaticInst::IsNonSpeculative)"
+            # For implicit stack operations, we should use *not* use the
+            # alternative addressing mode for loads/stores if the prefix is set
+            if not implicitStack:
                 self.memFlags += " | (machInst.legacy.addr ? " + \
                                  "(AddrSizeFlagBit << FlagShift) : 0)"
 
@@ -395,9 +403,11 @@ let {{
 
     class LdStSplitOp(LdStOp):
         def __init__(self, data, segment, addr, disp,
-                dataSize, addressSize, baseFlags, atCPL0, prefetch, nonSpec):
+                dataSize, addressSize, baseFlags, atCPL0, prefetch, nonSpec,
+                implicitStack):
             super(LdStSplitOp, self).__init__(0, segment, addr, disp,
-                dataSize, addressSize, baseFlags, atCPL0, prefetch, nonSpec)
+                dataSize, addressSize, baseFlags, atCPL0, prefetch, nonSpec,
+                implicitStack)
             (self.dataLow, self.dataHi) = data
 
         def getAllocator(self, microFlags):
@@ -435,7 +445,8 @@ let {{
     calculateEA = 'EA = SegBase + ' + segmentEAExpr
 
     def defineMicroLoadOp(mnemonic, code, bigCode='',
-                          mem_flags="0", big=True, nonSpec=False):
+                          mem_flags="0", big=True, nonSpec=False,
+                          implicitStack=False):
         global header_output
         global decoder_output
         global exec_output
@@ -460,17 +471,26 @@ let {{
             exec_output += MicroLoadInitiateAcc.subst(iop)
             exec_output += MicroLoadCompleteAcc.subst(iop)
 
+        if implicitStack:
+            # For instructions that implicitly access the stack, the address
+            # size is the same as the stack segment pointer size, not the
+            # address size if specified by the instruction prefix
+            addressSize = "env.stackSize"
+        else:
+            addressSize = "env.addressSize"
+
         base = LdStOp
         if big:
             base = BigLdStOp
         class LoadOp(base):
             def __init__(self, data, segment, addr, disp = 0,
                     dataSize="env.dataSize",
-                    addressSize="env.addressSize",
+                    addressSize=addressSize,
-                    atCPL0=False, prefetch=False, nonSpec=nonSpec):
+                    atCPL0=False, prefetch=False, nonSpec=nonSpec,
+                    implicitStack=implicitStack):
                 super(LoadOp, self).__init__(data, segment, addr,
                         disp, dataSize, addressSize, mem_flags,
-                        atCPL0, prefetch, nonSpec)
+                        atCPL0, prefetch, nonSpec, implicitStack)
                 self.className = Name
                 self.mnemonic = name
 
@@ -478,6 +498,10 @@ let {{
 
     defineMicroLoadOp('Ld', 'Data = merge(Data, Mem, dataSize);',
                             'Data = Mem & mask(dataSize * 8);')
+    # Load micro-op used in macro-ops that implicitly access the stack
+    defineMicroLoadOp('Ld_stack', 'Data = merge(Data, Mem, dataSize);',
+                                  'Data = Mem & mask(dataSize * 8);',
+                                  implicitStack=True)
     defineMicroLoadOp('Ldst', 'Data = merge(Data, Mem, dataSize);',
                               'Data = Mem & mask(dataSize * 8);',
                       '(StoreCheck << FlagShift)')
@@ -544,10 +568,11 @@ let {{
             def __init__(self, data, segment, addr, disp = 0,
                     dataSize="env.dataSize",
                     addressSize="env.addressSize",
-                    atCPL0=False, prefetch=False, nonSpec=nonSpec):
+                    atCPL0=False, prefetch=False, nonSpec=nonSpec,
+                    implicitStack=False):
                 super(LoadOp, self).__init__(data, segment, addr,
                         disp, dataSize, addressSize, mem_flags,
-                        atCPL0, prefetch, nonSpec)
+                        atCPL0, prefetch, nonSpec, implicitStack)
                 self.className = Name
                 self.mnemonic = name
 
@@ -574,7 +599,8 @@ let {{
                            '(StoreCheck << FlagShift) | Request::LOCKED_RMW',
                            nonSpec=True)
 
-    def defineMicroStoreOp(mnemonic, code, completeCode="", mem_flags="0"):
+    def defineMicroStoreOp(mnemonic, code, completeCode="", mem_flags="0",
+                           implicitStack=False):
         global header_output
         global decoder_output
         global exec_output
@@ -594,20 +620,31 @@ let {{
         exec_output += MicroStoreInitiateAcc.subst(iop)
         exec_output += MicroStoreCompleteAcc.subst(iop)
 
+        if implicitStack:
+            # For instructions that implicitly access the stack, the address
+            # size is the same as the stack segment pointer size, not the
+            # address size if specified by the instruction prefix
+            addressSize = "env.stackSize"
+        else:
+            addressSize = "env.addressSize"
+
         class StoreOp(LdStOp):
             def __init__(self, data, segment, addr, disp = 0,
                     dataSize="env.dataSize",
-                    addressSize="env.addressSize",
+                    addressSize=addressSize,
-                    atCPL0=False, nonSpec=False):
+                    atCPL0=False, nonSpec=False, implicitStack=implicitStack):
                 super(StoreOp, self).__init__(data, segment, addr, disp,
                         dataSize, addressSize, mem_flags, atCPL0, False,
-                        nonSpec)
+                        nonSpec, implicitStack)
                 self.className = Name
                 self.mnemonic = name
 
         microopClasses[name] = StoreOp
 
     defineMicroStoreOp('St', 'Mem = pick(Data, 2, dataSize);')
+    # Store micro-op used in macro-ops that implicitly access the stack
+    defineMicroStoreOp('St_stack', 'Mem = pick(Data, 2, dataSize);',
+                                   implicitStack=True)
     defineMicroStoreOp('Stul', 'Mem = pick(Data, 2, dataSize);',
             mem_flags="Request::LOCKED_RMW")
 
@@ -655,10 +692,10 @@ let {{
             def __init__(self, data, segment, addr, disp = 0,
                     dataSize="env.dataSize",
                     addressSize="env.addressSize",
-                    atCPL0=False, nonSpec=False):
+                    atCPL0=False, nonSpec=False, implicitStack=False):
                 super(StoreOp, self).__init__(data, segment, addr, disp,
                         dataSize, addressSize, mem_flags, atCPL0, False,
-                        nonSpec)
+                        nonSpec, implicitStack)
                 self.className = Name
                 self.mnemonic = name
 
@@ -694,7 +731,7 @@ let {{
         def __init__(self, data, segment, addr, disp = 0,
                 dataSize="env.dataSize", addressSize="env.addressSize"):
             super(LeaOp, self).__init__(data, segment, addr, disp,
-                    dataSize, addressSize, "0", False, False, False)
+                    dataSize, addressSize, "0", False, False, False, False)
             self.className = "Lea"
             self.mnemonic = "lea"
 
@@ -715,7 +752,7 @@ let {{
                 addressSize="env.addressSize"):
             super(TiaOp, self).__init__("InstRegIndex(NUM_INTREGS)", segment,
                     addr, disp, dataSize, addressSize, "0", False, False,
-                    False)
+                    False, False)
             self.className = "Tia"
             self.mnemonic = "tia"
 
@@ -727,10 +764,9 @@ let {{
                 addressSize="env.addressSize", atCPL0=False):
             super(CdaOp, self).__init__("InstRegIndex(NUM_INTREGS)", segment,
                     addr, disp, dataSize, addressSize, "Request::NO_ACCESS",
-                    atCPL0, False, False)
+                    atCPL0, False, False, False)
             self.className = "Cda"
             self.mnemonic = "cda"
 
     microopClasses["cda"] = CdaOp
 }};
-