On 10/06/2024 15:04, Torbjörn SVENSSON wrote:
Properly handle zero and sign extension for Armv8-M.baseline as
Cortex-M23 can have the security extension active.
Currently, there is an internal compiler error on Cortex-M23 for the
epilog processing of sign extension.
This patch addresses the following CVE-2024-0151 for Armv8-M.baseline.
gcc/ChangeLog:
PR target/115253
* config/arm/arm.cc (cmse_nonsecure_call_inline_register_clear):
Sign extend for Thumb1.
(thumb1_expand_prologue): Add zero/sign extend.
Signed-off-by: Torbjörn SVENSSON <torbjorn.svens...@foss.st.com>
Co-authored-by: Yvan ROUX <yvan.r...@foss.st.com>
---
gcc/config/arm/arm.cc | 71 ++++++++++++++++++++++++++++++++++++++-----
1 file changed, 63 insertions(+), 8 deletions(-)
diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc
index ea0c963a4d6..e7b4caf1083 100644
--- a/gcc/config/arm/arm.cc
+++ b/gcc/config/arm/arm.cc
@@ -19220,17 +19220,22 @@ cmse_nonsecure_call_inline_register_clear (void)
|| TREE_CODE (ret_type) == BOOLEAN_TYPE)
&& known_lt (GET_MODE_SIZE (TYPE_MODE (ret_type)), 4))
{
- machine_mode ret_mode = TYPE_MODE (ret_type);
+ rtx ret_reg = gen_rtx_REG (TYPE_MODE (ret_type), R0_REGNUM);
+ rtx si_reg = gen_rtx_REG (SImode, R0_REGNUM);
rtx extend;
if (TYPE_UNSIGNED (ret_type))
- extend = gen_rtx_ZERO_EXTEND (SImode,
- gen_rtx_REG (ret_mode,
R0_REGNUM));
+ extend = gen_rtx_SET (si_reg, gen_rtx_ZERO_EXTEND (SImode,
+ ret_reg));
else
- extend = gen_rtx_SIGN_EXTEND (SImode,
- gen_rtx_REG (ret_mode,
R0_REGNUM));
- emit_insn_after (gen_rtx_SET (gen_rtx_REG (SImode, R0_REGNUM),
- extend), insn);
-
+ /* Signed-extension is a special case because of
+ thumb1_extendhisi2. */
+ if (TARGET_THUMB1
You effectively have an 'else if' split across a comment here, and the
indentation looks weird. Either write 'else if' on one line (and re-indent
accordingly) or put this entire block inside braces.
+ && known_ge (GET_MODE_SIZE (TYPE_MODE (ret_type)), 2))
You can use known_eq here. We'll never have any value other than 2, given the
known_le (4) above and anyway it doesn't make sense to call extendhisi with any
other size.
+ extend = gen_thumb1_extendhisi2 (si_reg, ret_reg);
+ else
+ extend = gen_rtx_SET (si_reg, gen_rtx_SIGN_EXTEND (SImode,
+ ret_reg));
+ emit_insn_after (extend, insn);
}
@@ -27250,6 +27255,56 @@ thumb1_expand_prologue (void)
live_regs_mask = offsets->saved_regs_mask;
lr_needs_saving = live_regs_mask & (1 << LR_REGNUM);
Similar comments to above apply to the hunk below.
+ /* The AAPCS requires the callee to widen integral types narrower
+ than 32 bits to the full width of the register; but when handling
+ calls to non-secure space, we cannot trust the callee to have
+ correctly done so. So forcibly re-widen the result here. */
+ if (IS_CMSE_ENTRY (func_type))
+ {
+ function_args_iterator args_iter;
+ CUMULATIVE_ARGS args_so_far_v;
+ cumulative_args_t args_so_far;
+ bool first_param = true;
+ tree arg_type;
+ tree fndecl = current_function_decl;
+ tree fntype = TREE_TYPE (fndecl);
+ arm_init_cumulative_args (&args_so_far_v, fntype, NULL_RTX, fndecl);
+ args_so_far = pack_cumulative_args (&args_so_far_v);
+ FOREACH_FUNCTION_ARGS (fntype, arg_type, args_iter)
+ {
+ rtx arg_rtx;
+
+ if (VOID_TYPE_P (arg_type))
+ break;
+
+ function_arg_info arg (arg_type, /*named=*/true);
+ if (!first_param)
+ /* We should advance after processing the argument and pass
+ the argument we're advancing past. */
+ arm_function_arg_advance (args_so_far, arg);
+ first_param = false;
+ arg_rtx = arm_function_arg (args_so_far, arg);
+ gcc_assert (REG_P (arg_rtx));
+ if ((TREE_CODE (arg_type) == INTEGER_TYPE
+ || TREE_CODE (arg_type) == ENUMERAL_TYPE
+ || TREE_CODE (arg_type) == BOOLEAN_TYPE)
+ && known_lt (GET_MODE_SIZE (GET_MODE (arg_rtx)), 4))
+ {
+ rtx res_reg = gen_rtx_REG (SImode, REGNO (arg_rtx));
+ if (TYPE_UNSIGNED (arg_type))
+ emit_set_insn (res_reg, gen_rtx_ZERO_EXTEND (SImode, arg_rtx));
+ else
+ /* Signed-extension is a special case because of
+ thumb1_extendhisi2. */
+ if (known_ge (GET_MODE_SIZE (GET_MODE (arg_rtx)), 2))
+ emit_insn (gen_thumb1_extendhisi2 (res_reg, arg_rtx));
+ else
+ emit_set_insn (res_reg,
+ gen_rtx_SIGN_EXTEND (SImode, arg_rtx));
+ }
+ }
+ }
+
/* Extract a mask of the ones we can give to the Thumb's push instruction.
*/
l_mask = live_regs_mask & 0x40ff;
/* Then count how many other high registers will need to be pushed. */
OK with those changes.
R.
