Commit 56dfb700 authored by Matt Redfearn's avatar Matt Redfearn Committed by Ralf Baechle
Browse files

MIPS: Refactor handling of stack pointer in get_frame_info 



Commit 34c2f668 ("MIPS: microMIPS: Add unaligned access support.")
added handling of microMIPS instructions to manipulate the stack
pointer. The code that was added violates code style rules with long
lines caused by lots of nested conditionals.

The added code interprets (inline) any known stack pointer manipulation
instruction to find the stack frame size. Handling the microMIPS cases
added quite a bit of complication to this function.

Refactor is_sp_move_ins to perform the interpretation of the immediate
as the instruction manipulating the stack pointer is found. This reduces
the amount of indentation required in get_frame_info, and more closely
matches the operation of is_ra_save_ins.

Suggested-by: default avatarMaciej W. Rozycki <macro@imgtec.com>
Signed-off-by: default avatarMatt Redfearn <matt.redfearn@imgtec.com>
Cc: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16958/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 41885b02

arch/mips/kernel/process.c

+30 −31
Original line number Diff line number Diff line
@@ -313,9 +313,11 @@ static inline int is_jump_ins(union mips_instruction *ip) 
#endif

}



static inline int is_sp_move_ins(union mips_instruction *ip)

static inline int is_sp_move_ins(union mips_instruction *ip, int *frame_size)

{

#ifdef CONFIG_CPU_MICROMIPS

	unsigned short tmp;



	/*

	 * addiusp -imm

	 * addius5 sp,-imm
@@ -325,20 +327,39 @@ static inline int is_sp_move_ins(union mips_instruction *ip) 
	 * microMIPS is not more fun...

	 */

	if (mm_insn_16bit(ip->word >> 16)) {

		return (ip->mm16_r3_format.opcode == mm_pool16d_op &&

			ip->mm16_r3_format.simmediate & mm_addiusp_func) ||

		       (ip->mm16_r5_format.opcode == mm_pool16d_op &&

			ip->mm16_r5_format.rt == 29);

		if (ip->mm16_r3_format.opcode == mm_pool16d_op &&

		    ip->mm16_r3_format.simmediate & mm_addiusp_func) {

			tmp = ip->mm_b0_format.simmediate >> 1;

			tmp = ((tmp & 0x1ff) ^ 0x100) - 0x100;

			if ((tmp + 2) < 4) /* 0x0,0x1,0x1fe,0x1ff are special */

				tmp ^= 0x100;

			*frame_size = -(signed short)(tmp << 2);

			return 1;

		}

		if (ip->mm16_r5_format.opcode == mm_pool16d_op &&

		    ip->mm16_r5_format.rt == 29) {

			tmp = ip->mm16_r5_format.imm >> 1;

			*frame_size = -(signed short)(tmp & 0xf);

			return 1;

		}

		return 0;

	}



	return ip->mm_i_format.opcode == mm_addiu32_op &&

	       ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;

	if (ip->mm_i_format.opcode == mm_addiu32_op &&

	    ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29) {

		*frame_size = -ip->i_format.simmediate;

		return 1;

	}

#else

	/* addiu/daddiu sp,sp,-imm */

	if (ip->i_format.rs != 29 || ip->i_format.rt != 29)

		return 0;

	if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)



	if (ip->i_format.opcode == addiu_op ||

	    ip->i_format.opcode == daddiu_op) {

		*frame_size = -ip->i_format.simmediate;

		return 1;

	}

#endif

	return 0;

}
@@ -375,29 +396,7 @@ static int get_frame_info(struct mips_frame_info *info) 
		}



		if (!info->frame_size) {

			if (is_sp_move_ins(&insn))

			{

#ifdef CONFIG_CPU_MICROMIPS

				if (mm_insn_16bit(insn.word >> 16))

				{

					unsigned short tmp;



					if (ip->mm16_r3_format.simmediate & mm_addiusp_func)

					{

						tmp = ip->mm_b0_format.simmediate >> 1;

						tmp = ((tmp & 0x1ff) ^ 0x100) - 0x100;

						/* 0x0,0x1,0x1fe,0x1ff are special */

						if ((tmp + 2) < 4)

							tmp ^= 0x100;

						info->frame_size = -(signed short)(tmp << 2);

					} else {

						tmp = (ip->mm16_r5_format.imm >> 1);

						info->frame_size = -(signed short)(tmp & 0xf);

					}

				} else

#endif

				info->frame_size = - ip->i_format.simmediate;

			}

			is_sp_move_ins(&insn, &info->frame_size);

			continue;

		} else if (!saw_jump && is_jump_ins(ip)) {

			/*

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