Current get_frame_info implementation works on word boundary, this
can lead to alignment and endian issues in microMIPS mode,
due to:
1. microMIPS instructions are sequence of halfwords
2. microMIPS instructions can be one or two halfwords
3. microMIPS instructions are placed in 32-bit memory element,
in endian-dependent order.
Example:
insn1 = one halfword => word1, hword[0]
insn2 = two halfwords => word1, hword[1], word2, hword[0]
insn3 = one halfword => word2, hword[1]
Big Endian
hword[0] hword[1] hword[0] hword[1]
+-------------+-------------+-------------+-------------+
| insn1 | insn2 | insn2' | insn3 |
+-------------+-------------+-------------+-------------+
31 word1 0 31 word2 0
Little Endian
hword[1] hword[0] hword[1] hword[0]
+-------------+-------------+-------------+-------------+
| insn2 | insn1 | insn3 | insn2' |
+-------------+-------------+-------------+-------------+
31 word1 0 31 word2 0
This patch refactors microMIPS get_frame_info by implementing
fetch_instruction() to fetch words on word boundary, and
mmips_fetch_halfword() to assemble one or two halfwords into
microMIPS instructions for further processing.
This patch also fixes sibling call handling and schedule_mfi
initialization for microMIPS.
Signed-off-by: Tony Wu <tung7970@xxxxxxxxx>
Cc: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>
Cc: David Daney <david.daney@xxxxxxxxxx>
Cc: Steven J. Hill <Steven.Hill@xxxxxxxxxx>
---
arch/mips/kernel/process.c | 339 ++++++++++++++++++++++++++++----------------
1 file changed, 214 insertions(+), 125 deletions(-)
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index c6a041d..706bda8 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -211,124 +211,211 @@ struct mips_frame_info {
int pc_offset;
};
-#define J_TARGET(pc,target) \
- (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
-
static inline int is_ra_save_ins(union mips_instruction *ip)
{
-#ifdef CONFIG_CPU_MICROMIPS
- union mips_instruction mmi;
+ if (cpu_has_mmips) {
+ /*
+ * swsp ra,offset
+ * swm16 reglist,offset(sp)
+ *
+ * microMIPS is way more fun...
+ */
+ if ((ip->mm16_r5_format.opcode == mm_swsp16_op &&
+ ip->mm16_r5_format.rt == 31) ||
+ (ip->mm16_m_format.opcode == mm_pool16c_op &&
+ ip->mm16_m_format.func == mm_swm16_op))
+ return 1;
- /*
- * swsp ra,offset
- * swm16 reglist,offset(sp)
- * swm32 reglist,offset(sp)
- * sw32 ra,offset(sp)
- * jradiussp - NOT SUPPORTED
- *
- * microMIPS is way more fun...
- */
- if (mm_insn_16bit(ip->halfword[0])) {
- mmi.word = (ip->halfword[0] << 16);
- return ((mmi.mm16_r5_format.opcode == mm_swsp16_op &&
- mmi.mm16_r5_format.rt == 31) ||
- (mmi.mm16_m_format.opcode == mm_pool16c_op &&
- mmi.mm16_m_format.func == mm_swm16_op));
- }
- else {
- mmi.halfword[0] = ip->halfword[1];
- mmi.halfword[1] = ip->halfword[0];
- return ((mmi.mm_m_format.opcode == mm_pool32b_op &&
- mmi.mm_m_format.rd > 9 &&
- mmi.mm_m_format.base == 29 &&
- mmi.mm_m_format.func == mm_swm32_func) ||
- (mmi.i_format.opcode == mm_sw32_op &&
- mmi.i_format.rs == 29 &&
- mmi.i_format.rt == 31));
+ /*
+ * two-halfword instructions
+ *
+ * swm32 reglist,offset(sp)
+ * sw32 ra,offset(sp)
+ */
+ if ((ip->mm_m_format.opcode == mm_pool32b_op &&
+ ip->mm_m_format.rd >= 16 &&
+ ip->mm_m_format.base == 29 &&
+ ip->mm_m_format.func == mm_swm32_func) ||
+ (ip->mm_i_format.opcode == mm_sw32_op &&
+ ip->mm_i_format.rs == 29 &&
+ ip->mm_i_format.rt == 31))
+ return 1;
}
-#else
+
/* sw / sd $ra, offset($sp) */
- return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
+ return (ip->i_format.opcode == sw_op ||
+ ip->i_format.opcode == sd_op) &&
ip->i_format.rs == 29 &&
ip->i_format.rt == 31;
-#endif
}
static inline int is_jump_ins(union mips_instruction *ip)
{
-#ifdef CONFIG_CPU_MICROMIPS
- /*
- * jr16,jrc,jalr16,jalr16
- * jal
- * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
- * jraddiusp - NOT SUPPORTED
- *
- * microMIPS is kind of more fun...
- */
- union mips_instruction mmi;
-
- mmi.word = (ip->halfword[0] << 16);
+ if (cpu_has_mmips) {
+ /*
+ * jr16,jrc,jalr16,jalr16
+ * jal
+ * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
+ * jraddiusp
+ *
+ * microMIPS is kind of more fun...
+ */
+ if ((ip->mm16_r5_format.opcode == mm_pool16c_op &&
+ ((ip->mm16_r5_format.rt & ~0x3) == mm_jr16_op ||
+ ip->mm16_r5_format.rt == mm_jraddiusp_op)))
+ return 1;
+
+ /* two-halfword instructions */
+ if (ip->j_format.opcode == mm_jal32_op ||
+ ip->j_format.opcode == mm_jals32_op ||
+ ip->j_format.opcode == mm_j32_op ||
+ (ip->r_format.opcode == mm_pool32a_op &&
+ ip->r_format.func == mm_pool32axf_op &&
+ ((ip->u_format.uimmediate >> 6) & ~0x140) == mm_jalr_op))
+ return 1;
+ }
- if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
- (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
- ip->j_format.opcode == mm_jal32_op)
- return 1;
- if (ip->r_format.opcode != mm_pool32a_op ||
- ip->r_format.func != mm_pool32axf_op)
- return 0;
- return (((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op);
-#else
- if (ip->j_format.opcode == j_op)
- return 1;
- if (ip->j_format.opcode == jal_op)
- return 1;
- if (ip->r_format.opcode != spec_op)
- return 0;
- return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
-#endif
+ return (ip->j_format.opcode == j_op ||
+ ip->j_format.opcode == jal_op ||
+ (ip->r_format.opcode == spec_op &&
+ (ip->r_format.func == jalr_op ||
+ ip->r_format.func == jr_op)));
}
static inline int is_sp_move_ins(union mips_instruction *ip)
{
-#ifdef CONFIG_CPU_MICROMIPS
- /*
- * addiusp -imm
- * addius5 sp,-imm
- * addiu32 sp,sp,-imm
- * jradiussp - NOT SUPPORTED
- *
- * microMIPS is not more fun...
- */
- if (mm_insn_16bit(ip->halfword[0])) {
- union mips_instruction mmi;
-
- mmi.word = (ip->halfword[0] << 16);
- return ((mmi.mm16_r3_format.opcode == mm_pool16d_op &&
- mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
- (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
- mmi.mm16_r5_format.rt == 29));
+ if (cpu_has_mmips) {
+ /*
+ * addiusp -imm
+ * addius5 sp,-imm
+ * addiu32 sp,sp,-imm
+ *
+ * microMIPS is not more fun...
+ */
+ if (ip->mm16_r5_format.opcode == mm_pool16d_op &&
+ ((ip->mm16_r5_format.simmediate & mm_addiusp_func) ||
+ (ip->mm16_r5_format.rt == 29)))
+ return 1;
+
+ /* two-halfword instructions */
+ if (ip->mm_i_format.opcode == mm_addiu32_op &&
+ ip->mm_i_format.rt == 29 &&
+ ip->mm_i_format.rs == 29)
+ return 1;
}
- return (ip->mm_i_format.opcode == mm_addiu32_op &&
- ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29);
-#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)
- return 1;
-#endif
- return 0;
+ return (ip->i_format.rs == 29 &&
+ ip->i_format.rt == 29 &&
+ (ip->i_format.opcode == addiu_op ||
+ ip->i_format.opcode == daddiu_op));
+}
+
+/*
+ * A few fun facts on microMIPS (MIPS32)
+ *
+ * 1. microMIPS instructions are sequence of halfwords
+ * 2. microMIPS instructions may contain one to two halfwords
+ * 3. microMIPS instructions are placed in 32-bit memory element,
+ * in endian-dependent order.
+ *
+ * Example:
+ * insn1 = one halfword => word1, hword[0]
+ * insn2 = two halfwords => word1, hword[1], word2, hword[0]
+ * insn3 = one halfword => word2, hword[1]
+ *
+ * Big Endian
+ * hword[0] hword[1] hword[0] hword[1]
+ * +-------------+-------------+-------------+-------------+
+ * | insn1 | insn2 | insn2' | insn3 |
+ * +-------------+-------------+-------------+-------------+
+ * 31 word1 0 31 word2 0
+ *
+ * Little Endian
+ * hword[1] hword[0] hword[1] hword[0]
+ * +-------------+-------------+-------------+-------------+
+ * | insn2 | insn1 | insn3 | insn2' |
+ * +-------------+-------------+-------------+-------------+
+ * 31 word1 0 31 word2 0
+ *
+ * mmips_fetch_halfword does the followings:
+ *
+ * 1. fetch word from word-aligned address
+ * 2. access the fetched word using halfword (defeat endian issue)
+ * 3. assemble microMIPS instruction with one or two halfwords
+ */
+static void mmips_fetch_halfword(union mips_instruction **ip,
+ unsigned short *this_halfword,
+ unsigned short *prev_halfword)
+{
+ if (*prev_halfword) {
+ *this_halfword = *prev_halfword;
+ *prev_halfword = 0;
+ } else {
+ /* advance pointer to next word */
+ *this_halfword = (*ip)->halfword[0];
+ *prev_halfword = (*ip)->halfword[1];
+ *ip += 1;
+ }
+}
+
+static void fetch_instruction(union mips_instruction **ip,
+ union mips_instruction *mi,
+ unsigned short *prev_halfword)
+{
+ if (cpu_has_mmips) {
+ /* fetch the first microMIPS instruction */
+ mmips_fetch_halfword(ip, &mi->halfword[0], prev_halfword);
+
+ /* fetch the second half if it is a 32bit one */
+ if (mm_insn_16bit(mi->halfword[0]))
+ mi->halfword[1] = 0;
+ else
+ mmips_fetch_halfword(ip, &mi->halfword[1],
+ prev_halfword);
+ } else {
+ /* do simple assignment for mips32 mode */
+ *mi = **ip;
+ *ip += 1;
+ }
+}
+
+static int get_frame_size(union mips_instruction *ip)
+{
+ unsigned short tmp;
+ int size = 0;
+
+ if (cpu_has_mmips &&
+ mm_insn_16bit(ip->halfword[0])) {
+ /*
+ * addiusp -imm
+ * addius5 sp,-imm
+ */
+ if (ip->halfword[0] & mm_addiusp_func) {
+ tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
+ size = -(signed short)(tmp |
+ ((tmp & 0x100) ? 0xfe00 : 0));
+ } else {
+ tmp = (ip->halfword[0] >> 1);
+ size = -(signed short)(tmp & 0xf);
+ }
+ } else {
+ /*
+ * addiu32 sp,sp,-imm
+ * addiu/daddiu sp,sp,-imm
+ */
+ size = - ip->i_format.simmediate;
+ }
+
+ return size;
}
static int get_frame_info(struct mips_frame_info *info)
{
-#ifdef CONFIG_CPU_MICROMIPS
- union mips_instruction *ip = (void *) (((char *) info->func) - 1);
-#else
union mips_instruction *ip = info->func;
-#endif
+ union mips_instruction inst, *max_ip;
unsigned max_insns = info->func_size / sizeof(union mips_instruction);
- unsigned i;
+ unsigned short halfword = 0;
info->pc_offset = -1;
info->frame_size = 0;
@@ -340,37 +427,25 @@ static int get_frame_info(struct mips_frame_info *info)
max_insns = 128U; /* unknown function size */
max_insns = min(128U, max_insns);
- for (i = 0; i < max_insns; i++, ip++) {
+ if (cpu_has_mmips) {
+ /* align start address to word boundary, lose mode bit. */
+ ip = (union mips_instruction *)((unsigned long)ip & ~0x3);
+ }
+ max_ip = ip + max_insns * sizeof(union mips_instruction);
+
+ while (ip < max_ip) {
+ fetch_instruction(&ip, &inst, &halfword);
- if (is_jump_ins(ip))
+ if (is_jump_ins(&inst))
break;
if (!info->frame_size) {
- if (is_sp_move_ins(ip))
- {
-#ifdef CONFIG_CPU_MICROMIPS
- if (mm_insn_16bit(ip->halfword[0]))
- {
- unsigned short tmp;
-
- if (ip->halfword[0] & mm_addiusp_func)
- {
- tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
- info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
- } else {
- tmp = (ip->halfword[0] >> 1);
- info->frame_size = -(signed short)(tmp & 0xf);
- }
- ip = (void *) &ip->halfword[1];
- ip--;
- } else
-#endif
- info->frame_size = - ip->i_format.simmediate;
- }
+ if (is_sp_move_ins(&inst))
+ info->frame_size = get_frame_size(&inst);
continue;
}
- if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
+ if (info->pc_offset == -1 && is_ra_save_ins(&inst)) {
info->pc_offset =
- ip->i_format.simmediate / sizeof(long);
+ inst.i_format.simmediate / sizeof(long);
break;
}
}
@@ -390,20 +465,34 @@ static unsigned long get___schedule_addr(void)
{
return kallsyms_lookup_name("__schedule");
}
-#else
+#else /* CONFIG_KALLSYMS */
static unsigned long get___schedule_addr(void)
{
union mips_instruction *ip = (void *)schedule;
+ union mips_instruction inst;
+ union mips_instruction *max_ip;
int max_insns = 8;
- int i;
+ unsigned short halfword = 0;
- for (i = 0; i < max_insns; i++, ip++) {
- if (ip->j_format.opcode == j_op)
- return J_TARGET(ip, ip->j_format.target);
+ if (cpu_has_mmips) {
+ /* align start address to word boundary, lose mode bit */
+ ip = (union mips_instruction *)((unsigned long)ip & ~0x3);
+ }
+ max_ip = ip + max_insns * sizeof(union mips_instruction);
+
+ while (ip < max_ip) {
+ fetch_instruction(&ip, &inst, &halfword);
+ if (cpu_has_mmips &&
+ inst.j_format.opcode == mm_j32_op)
+ return (((unsigned long)(ip+1) & 0xf8000000) |
+ (inst.j_format.target << 1));
+ else if (inst.j_format.opcode == j_op)
+ return (((unsigned long)(ip) & 0xf0000000) |
+ (inst.j_format.target << 2));
}
return 0;
}
-#endif
+#endif /* !CONFIG_KALLSYMS */
static int __init frame_info_init(void)
{
--
1.7.10.2
