diff mbox series

[18/23] tcg/tci: Move stack bounds check to compile-time

Message ID 20210128082331.196801-19-richard.henderson@linaro.org
State Superseded
Headers show
Series TCI fixes and cleanups | expand

Commit Message

Richard Henderson Jan. 28, 2021, 8:23 a.m. UTC 
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.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 tcg/tci.c                |  2 --
 tcg/tci/tcg-target.c.inc | 13 +++++++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

-- 
2.25.1

Comments

Alex Bennée Jan. 28, 2021, 4:37 p.m. UTC | #1 
Richard Henderson <richard.henderson@linaro.org> writes:

> 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.


You confused me with the statement compile time until I realised which
compile time it was ;-)

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>


-- 
Alex Bennée
diff mbox series

Patch

diff --git a/tcg/tci.c b/tcg/tci.c
index 67875636a5..c4c303f874 100644
--- a/tcg/tci.c
+++ b/tcg/tci.c
@@ -623,7 +623,6 @@  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;
 
@@ -879,7 +878,6 @@  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 15981265db..a60fa524a4 100644
--- a/tcg/tci/tcg-target.c.inc
+++ b/tcg/tci/tcg-target.c.inc
@@ -484,10 +484,20 @@  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);
@@ -623,6 +633,7 @@  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]);
@@ -825,6 +836,8 @@  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);