From 6050d55ca84fe96018e99afa5e1403341c538f3f Mon Sep 17 00:00:00 2001 From: Thomas Preud'homme Date: Thu, 28 Sep 2017 16:13:01 +0000 Subject: [ARM] Remove ARMv8-M code for D17-D31 Function cmse_nonsecure_entry_clear_before_return has code to deal with high VFP register (D16-D31) while ARMv8-M Baseline and Mainline both do not support more than 16 double VFP registers (D0-D15). This makes this security-sensitive code harder to read for not much benefit since libcall for cmse_nonsecure_call functions do not deal with those high VFP registers anyway. This commit gets rid of this code for simplicity and fixes 2 issues in the same function: - stop the first loop when reaching maxregno to avoid dealing with VFP registers if targetting Thumb-1 or using -mfloat-abi=soft - include maxregno in that loop 2017-09-28 Thomas Preud'homme gcc/ * config/arm/arm.c (arm_option_override): Forbid ARMv8-M Security Extensions with more than 16 double VFP registers. (cmse_nonsecure_entry_clear_before_return): Remove second entry of to_clear_mask and all code related to it. Replace the remaining entry by a sbitmap and adapt code accordingly. From-SVN: r253256 --- gcc/config/arm/arm.c | 64 ++++++++++++++++++++++++++++++++-------------------- 1 file changed, 40 insertions(+), 24 deletions(-) (limited to 'gcc/config') diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c index 363f549..4cddf3b 100644 --- a/gcc/config/arm/arm.c +++ b/gcc/config/arm/arm.c @@ -3669,6 +3669,11 @@ arm_option_override (void) if (use_cmse && !arm_arch_cmse) error ("target CPU does not support ARMv8-M Security Extensions"); + /* We don't clear D16-D31 VFP registers for cmse_nonsecure_call functions + and ARMv8-M Baseline and Mainline do not allow such configuration. */ + if (use_cmse && LAST_VFP_REGNUM > LAST_LO_VFP_REGNUM) + error ("ARMv8-M Security Extensions incompatible with selected FPU"); + /* Disable scheduling fusion by default if it's not armv7 processor or doesn't prefer ldrd/strd. */ if (flag_schedule_fusion == 2 @@ -25075,42 +25080,37 @@ thumb1_expand_prologue (void) void cmse_nonsecure_entry_clear_before_return (void) { - uint64_t to_clear_mask[2]; + int regno, maxregno = TARGET_HARD_FLOAT ? LAST_VFP_REGNUM : IP_REGNUM; uint32_t padding_bits_to_clear = 0; uint32_t * padding_bits_to_clear_ptr = &padding_bits_to_clear; - int regno, maxregno = IP_REGNUM; + auto_sbitmap to_clear_bitmap (maxregno + 1); tree result_type; rtx result_rtl; - to_clear_mask[0] = (1ULL << (NUM_ARG_REGS)) - 1; - to_clear_mask[0] |= (1ULL << IP_REGNUM); + bitmap_clear (to_clear_bitmap); + bitmap_set_range (to_clear_bitmap, R0_REGNUM, NUM_ARG_REGS); + bitmap_set_bit (to_clear_bitmap, IP_REGNUM); /* If we are not dealing with -mfloat-abi=soft we will need to clear VFP - registers. We also check that TARGET_HARD_FLOAT and !TARGET_THUMB1 hold - to make sure the instructions used to clear them are present. */ - if (TARGET_HARD_FLOAT && !TARGET_THUMB1) + registers. */ + if (TARGET_HARD_FLOAT) { - uint64_t float_mask = (1ULL << (D7_VFP_REGNUM + 1)) - 1; - maxregno = LAST_VFP_REGNUM; + int float_bits = D7_VFP_REGNUM - FIRST_VFP_REGNUM + 1; - float_mask &= ~((1ULL << FIRST_VFP_REGNUM) - 1); - to_clear_mask[0] |= float_mask; - - float_mask = (1ULL << (maxregno - 63)) - 1; - to_clear_mask[1] = float_mask; + bitmap_set_range (to_clear_bitmap, FIRST_VFP_REGNUM, float_bits); /* Make sure we don't clear the two scratch registers used to clear the relevant FPSCR bits in output_return_instruction. */ emit_use (gen_rtx_REG (SImode, IP_REGNUM)); - to_clear_mask[0] &= ~(1ULL << IP_REGNUM); + bitmap_clear_bit (to_clear_bitmap, IP_REGNUM); emit_use (gen_rtx_REG (SImode, 4)); - to_clear_mask[0] &= ~(1ULL << 4); + bitmap_clear_bit (to_clear_bitmap, 4); } /* If the user has defined registers to be caller saved, these are no longer restored by the function before returning and must thus be cleared for security purposes. */ - for (regno = NUM_ARG_REGS; regno < LAST_VFP_REGNUM; regno++) + for (regno = NUM_ARG_REGS; regno <= maxregno; regno++) { /* We do not touch registers that can be used to pass arguments as per the AAPCS, since these should never be made callee-saved by user @@ -25120,29 +25120,45 @@ cmse_nonsecure_entry_clear_before_return (void) if (IN_RANGE (regno, IP_REGNUM, PC_REGNUM)) continue; if (call_used_regs[regno]) - to_clear_mask[regno / 64] |= (1ULL << (regno % 64)); + bitmap_set_bit (to_clear_bitmap, regno); } /* Make sure we do not clear the registers used to return the result in. */ result_type = TREE_TYPE (DECL_RESULT (current_function_decl)); if (!VOID_TYPE_P (result_type)) { + uint64_t to_clear_return_mask; result_rtl = arm_function_value (result_type, current_function_decl, 0); /* No need to check that we return in registers, because we don't support returning on stack yet. */ - to_clear_mask[0] - &= ~compute_not_to_clear_mask (result_type, result_rtl, 0, - padding_bits_to_clear_ptr); + gcc_assert (REG_P (result_rtl)); + to_clear_return_mask + = compute_not_to_clear_mask (result_type, result_rtl, 0, + padding_bits_to_clear_ptr); + if (to_clear_return_mask) + { + gcc_assert ((unsigned) maxregno < sizeof (long long) * __CHAR_BIT__); + for (regno = R0_REGNUM; regno <= maxregno; regno++) + { + if (to_clear_return_mask & (1ULL << regno)) + bitmap_clear_bit (to_clear_bitmap, regno); + } + } } if (padding_bits_to_clear != 0) { rtx reg_rtx; + auto_sbitmap to_clear_arg_regs_bitmap (R0_REGNUM + NUM_ARG_REGS); + /* Padding bits to clear is not 0 so we know we are dealing with returning a composite type, which only uses r0. Let's make sure that r1-r3 is cleared too, we will use r1 as a scratch register. */ - gcc_assert ((to_clear_mask[0] & 0xe) == 0xe); + bitmap_clear (to_clear_arg_regs_bitmap); + bitmap_set_range (to_clear_arg_regs_bitmap, R0_REGNUM + 1, + NUM_ARG_REGS - 1); + gcc_assert (bitmap_subset_p (to_clear_arg_regs_bitmap, to_clear_bitmap)); reg_rtx = gen_rtx_REG (SImode, R1_REGNUM); @@ -25164,7 +25180,7 @@ cmse_nonsecure_entry_clear_before_return (void) for (regno = R0_REGNUM; regno <= maxregno; regno++) { - if (!(to_clear_mask[regno / 64] & (1ULL << (regno % 64)))) + if (!bitmap_bit_p (to_clear_bitmap, regno)) continue; if (IS_VFP_REGNUM (regno)) @@ -25173,7 +25189,7 @@ cmse_nonsecure_entry_clear_before_return (void) be cleared, use vmov. */ if (TARGET_VFP_DOUBLE && VFP_REGNO_OK_FOR_DOUBLE (regno) - && to_clear_mask[regno / 64] & (1ULL << ((regno % 64) + 1))) + && bitmap_bit_p (to_clear_bitmap, regno + 1)) { emit_move_insn (gen_rtx_REG (DFmode, regno), CONST1_RTX (DFmode)); -- cgit v1.1