From: Richard Henderson <richard.henderson@linaro.org>
Date: Thu, 28 Jan 2021 06:04:43 +0000 (-1000)
Subject: tcg/tci: Move stack bounds check to compile-time
X-Git-Tag: qemu-xen-4.16.0-rc4~354^2~26
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=53f405569cf84eb08756a53ad722d4dbe07023ec;p=qemu-xen.git

tcg/tci: Move stack bounds check to compile-time

The existing check was incomplete:
(1) Only applied to two of the 7 stores, and not to the loads at all.
(2) Only checked the upper, but not the lower bound of the stack.

Doing this at compile time means that we don't need to do it
at runtime as well.

Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---

diff --git a/tcg/tci.c b/tcg/tci.c
index fe935e71a3..ee2cd7dfa2 100644
--- a/tcg/tci.c
+++ b/tcg/tci.c
@@ -628,7 +628,6 @@ uintptr_t QEMU_DISABLE_CFI tcg_qemu_tb_exec(CPUArchState *env,
             t0 = tci_read_r32(regs, &tb_ptr);
             t1 = tci_read_r(regs, &tb_ptr);
             t2 = tci_read_s32(&tb_ptr);
-            tci_assert(t1 != sp_value || (int32_t)t2 < 0);
             *(uint32_t *)(t1 + t2) = t0;
             break;
 
@@ -884,7 +883,6 @@ uintptr_t QEMU_DISABLE_CFI tcg_qemu_tb_exec(CPUArchState *env,
             t0 = tci_read_r64(regs, &tb_ptr);
             t1 = tci_read_r(regs, &tb_ptr);
             t2 = tci_read_s32(&tb_ptr);
-            tci_assert(t1 != sp_value || (int32_t)t2 < 0);
             *(uint64_t *)(t1 + t2) = t0;
             break;
 
diff --git a/tcg/tci/tcg-target.c.inc b/tcg/tci/tcg-target.c.inc
index f0f6b13112..82efb9af60 100644
--- a/tcg/tci/tcg-target.c.inc
+++ b/tcg/tci/tcg-target.c.inc
@@ -375,10 +375,20 @@ static void tci_out_label(TCGContext *s, TCGLabel *label)
     }
 }
 
+static void stack_bounds_check(TCGReg base, target_long offset)
+{
+    if (base == TCG_REG_CALL_STACK) {
+        tcg_debug_assert(offset < 0);
+        tcg_debug_assert(offset >= -(CPU_TEMP_BUF_NLONGS * sizeof(long)));
+    }
+}
+
 static void tcg_out_ld(TCGContext *s, TCGType type, TCGReg ret, TCGReg arg1,
                        intptr_t arg2)
 {
     uint8_t *old_code_ptr = s->code_ptr;
+
+    stack_bounds_check(arg1, arg2);
     if (type == TCG_TYPE_I32) {
         tcg_out_op_t(s, INDEX_op_ld_i32);
         tcg_out_r(s, ret);
@@ -514,6 +524,7 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, const TCGArg *args,
     case INDEX_op_st16_i64:
     case INDEX_op_st32_i64:
     case INDEX_op_st_i64:
+        stack_bounds_check(args[1], args[2]);
         tcg_out_r(s, args[0]);
         tcg_out_r(s, args[1]);
         tcg_debug_assert(args[2] == (int32_t)args[2]);
@@ -716,6 +727,8 @@ static void tcg_out_st(TCGContext *s, TCGType type, TCGReg arg, TCGReg arg1,
                        intptr_t arg2)
 {
     uint8_t *old_code_ptr = s->code_ptr;
+
+    stack_bounds_check(arg1, arg2);
     if (type == TCG_TYPE_I32) {
         tcg_out_op_t(s, INDEX_op_st_i32);
         tcg_out_r(s, arg);