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-rw-r--r--arch/mips/kernel/branch.c503
1 files changed, 460 insertions, 43 deletions
diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c
index 32103cc2a25..7b2df224f04 100644
--- a/arch/mips/kernel/branch.c
+++ b/arch/mips/kernel/branch.c
@@ -9,37 +9,404 @@
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/signal.h>
+#include <linux/module.h>
#include <asm/branch.h>
#include <asm/cpu.h>
#include <asm/cpu-features.h>
#include <asm/fpu.h>
+#include <asm/fpu_emulator.h>
#include <asm/inst.h>
#include <asm/ptrace.h>
#include <asm/uaccess.h>
/*
- * Compute the return address and do emulate branch simulation, if required.
+ * Calculate and return exception PC in case of branch delay slot
+ * for microMIPS and MIPS16e. It does not clear the ISA mode bit.
*/
-int __compute_return_epc(struct pt_regs *regs)
+int __isa_exception_epc(struct pt_regs *regs)
{
- unsigned int __user *addr;
- unsigned int bit, fcr31, dspcontrol;
+ unsigned short inst;
+ long epc = regs->cp0_epc;
+
+ /* Calculate exception PC in branch delay slot. */
+ if (__get_user(inst, (u16 __user *) msk_isa16_mode(epc))) {
+ /* This should never happen because delay slot was checked. */
+ force_sig(SIGSEGV, current);
+ return epc;
+ }
+ if (cpu_has_mips16) {
+ if (((union mips16e_instruction)inst).ri.opcode
+ == MIPS16e_jal_op)
+ epc += 4;
+ else
+ epc += 2;
+ } else if (mm_insn_16bit(inst))
+ epc += 2;
+ else
+ epc += 4;
+
+ return epc;
+}
+
+/* (microMIPS) Convert 16-bit register encoding to 32-bit register encoding. */
+static const unsigned int reg16to32map[8] = {16, 17, 2, 3, 4, 5, 6, 7};
+
+int __mm_isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,
+ unsigned long *contpc)
+{
+ union mips_instruction insn = (union mips_instruction)dec_insn.insn;
+ int bc_false = 0;
+ unsigned int fcr31;
+ unsigned int bit;
+
+ if (!cpu_has_mmips)
+ return 0;
+
+ switch (insn.mm_i_format.opcode) {
+ case mm_pool32a_op:
+ if ((insn.mm_i_format.simmediate & MM_POOL32A_MINOR_MASK) ==
+ mm_pool32axf_op) {
+ switch (insn.mm_i_format.simmediate >>
+ MM_POOL32A_MINOR_SHIFT) {
+ case mm_jalr_op:
+ case mm_jalrhb_op:
+ case mm_jalrs_op:
+ case mm_jalrshb_op:
+ if (insn.mm_i_format.rt != 0) /* Not mm_jr */
+ regs->regs[insn.mm_i_format.rt] =
+ regs->cp0_epc +
+ dec_insn.pc_inc +
+ dec_insn.next_pc_inc;
+ *contpc = regs->regs[insn.mm_i_format.rs];
+ return 1;
+ }
+ }
+ break;
+ case mm_pool32i_op:
+ switch (insn.mm_i_format.rt) {
+ case mm_bltzals_op:
+ case mm_bltzal_op:
+ regs->regs[31] = regs->cp0_epc +
+ dec_insn.pc_inc +
+ dec_insn.next_pc_inc;
+ /* Fall through */
+ case mm_bltz_op:
+ if ((long)regs->regs[insn.mm_i_format.rs] < 0)
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ (insn.mm_i_format.simmediate << 1);
+ else
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ dec_insn.next_pc_inc;
+ return 1;
+ case mm_bgezals_op:
+ case mm_bgezal_op:
+ regs->regs[31] = regs->cp0_epc +
+ dec_insn.pc_inc +
+ dec_insn.next_pc_inc;
+ /* Fall through */
+ case mm_bgez_op:
+ if ((long)regs->regs[insn.mm_i_format.rs] >= 0)
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ (insn.mm_i_format.simmediate << 1);
+ else
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ dec_insn.next_pc_inc;
+ return 1;
+ case mm_blez_op:
+ if ((long)regs->regs[insn.mm_i_format.rs] <= 0)
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ (insn.mm_i_format.simmediate << 1);
+ else
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ dec_insn.next_pc_inc;
+ return 1;
+ case mm_bgtz_op:
+ if ((long)regs->regs[insn.mm_i_format.rs] <= 0)
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ (insn.mm_i_format.simmediate << 1);
+ else
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ dec_insn.next_pc_inc;
+ return 1;
+ case mm_bc2f_op:
+ case mm_bc1f_op:
+ bc_false = 1;
+ /* Fall through */
+ case mm_bc2t_op:
+ case mm_bc1t_op:
+ preempt_disable();
+ if (is_fpu_owner())
+ asm volatile("cfc1\t%0,$31" : "=r" (fcr31));
+ else
+ fcr31 = current->thread.fpu.fcr31;
+ preempt_enable();
+
+ if (bc_false)
+ fcr31 = ~fcr31;
+
+ bit = (insn.mm_i_format.rs >> 2);
+ bit += (bit != 0);
+ bit += 23;
+ if (fcr31 & (1 << bit))
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ (insn.mm_i_format.simmediate << 1);
+ else
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc + dec_insn.next_pc_inc;
+ return 1;
+ }
+ break;
+ case mm_pool16c_op:
+ switch (insn.mm_i_format.rt) {
+ case mm_jalr16_op:
+ case mm_jalrs16_op:
+ regs->regs[31] = regs->cp0_epc +
+ dec_insn.pc_inc + dec_insn.next_pc_inc;
+ /* Fall through */
+ case mm_jr16_op:
+ *contpc = regs->regs[insn.mm_i_format.rs];
+ return 1;
+ }
+ break;
+ case mm_beqz16_op:
+ if ((long)regs->regs[reg16to32map[insn.mm_b1_format.rs]] == 0)
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ (insn.mm_b1_format.simmediate << 1);
+ else
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc + dec_insn.next_pc_inc;
+ return 1;
+ case mm_bnez16_op:
+ if ((long)regs->regs[reg16to32map[insn.mm_b1_format.rs]] != 0)
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ (insn.mm_b1_format.simmediate << 1);
+ else
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc + dec_insn.next_pc_inc;
+ return 1;
+ case mm_b16_op:
+ *contpc = regs->cp0_epc + dec_insn.pc_inc +
+ (insn.mm_b0_format.simmediate << 1);
+ return 1;
+ case mm_beq32_op:
+ if (regs->regs[insn.mm_i_format.rs] ==
+ regs->regs[insn.mm_i_format.rt])
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ (insn.mm_i_format.simmediate << 1);
+ else
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ dec_insn.next_pc_inc;
+ return 1;
+ case mm_bne32_op:
+ if (regs->regs[insn.mm_i_format.rs] !=
+ regs->regs[insn.mm_i_format.rt])
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc +
+ (insn.mm_i_format.simmediate << 1);
+ else
+ *contpc = regs->cp0_epc +
+ dec_insn.pc_inc + dec_insn.next_pc_inc;
+ return 1;
+ case mm_jalx32_op:
+ regs->regs[31] = regs->cp0_epc +
+ dec_insn.pc_inc + dec_insn.next_pc_inc;
+ *contpc = regs->cp0_epc + dec_insn.pc_inc;
+ *contpc >>= 28;
+ *contpc <<= 28;
+ *contpc |= (insn.j_format.target << 2);
+ return 1;
+ case mm_jals32_op:
+ case mm_jal32_op:
+ regs->regs[31] = regs->cp0_epc +
+ dec_insn.pc_inc + dec_insn.next_pc_inc;
+ /* Fall through */
+ case mm_j32_op:
+ *contpc = regs->cp0_epc + dec_insn.pc_inc;
+ *contpc >>= 27;
+ *contpc <<= 27;
+ *contpc |= (insn.j_format.target << 1);
+ set_isa16_mode(*contpc);
+ return 1;
+ }
+ return 0;
+}
+
+/*
+ * Compute return address and emulate branch in microMIPS mode after an
+ * exception only. It does not handle compact branches/jumps and cannot
+ * be used in interrupt context. (Compact branches/jumps do not cause
+ * exceptions.)
+ */
+int __microMIPS_compute_return_epc(struct pt_regs *regs)
+{
+ u16 __user *pc16;
+ u16 halfword;
+ unsigned int word;
+ unsigned long contpc;
+ struct mm_decoded_insn mminsn = { 0 };
+
+ mminsn.micro_mips_mode = 1;
+
+ /* This load never faults. */
+ pc16 = (unsigned short __user *)msk_isa16_mode(regs->cp0_epc);
+ __get_user(halfword, pc16);
+ pc16++;
+ contpc = regs->cp0_epc + 2;
+ word = ((unsigned int)halfword << 16);
+ mminsn.pc_inc = 2;
+
+ if (!mm_insn_16bit(halfword)) {
+ __get_user(halfword, pc16);
+ pc16++;
+ contpc = regs->cp0_epc + 4;
+ mminsn.pc_inc = 4;
+ word |= halfword;
+ }
+ mminsn.insn = word;
+
+ if (get_user(halfword, pc16))
+ goto sigsegv;
+ mminsn.next_pc_inc = 2;
+ word = ((unsigned int)halfword << 16);
+
+ if (!mm_insn_16bit(halfword)) {
+ pc16++;
+ if (get_user(halfword, pc16))
+ goto sigsegv;
+ mminsn.next_pc_inc = 4;
+ word |= halfword;
+ }
+ mminsn.next_insn = word;
+
+ mm_isBranchInstr(regs, mminsn, &contpc);
+
+ regs->cp0_epc = contpc;
+
+ return 0;
+
+sigsegv:
+ force_sig(SIGSEGV, current);
+ return -EFAULT;
+}
+
+/*
+ * Compute return address and emulate branch in MIPS16e mode after an
+ * exception only. It does not handle compact branches/jumps and cannot
+ * be used in interrupt context. (Compact branches/jumps do not cause
+ * exceptions.)
+ */
+int __MIPS16e_compute_return_epc(struct pt_regs *regs)
+{
+ u16 __user *addr;
+ union mips16e_instruction inst;
+ u16 inst2;
+ u32 fullinst;
long epc;
- union mips_instruction insn;
epc = regs->cp0_epc;
- if (epc & 3)
- goto unaligned;
- /*
- * Read the instruction
- */
- addr = (unsigned int __user *) epc;
- if (__get_user(insn.word, addr)) {
+ /* Read the instruction. */
+ addr = (u16 __user *)msk_isa16_mode(epc);
+ if (__get_user(inst.full, addr)) {
force_sig(SIGSEGV, current);
return -EFAULT;
}
+ switch (inst.ri.opcode) {
+ case MIPS16e_extend_op:
+ regs->cp0_epc += 4;
+ return 0;
+
+ /*
+ * JAL and JALX in MIPS16e mode
+ */
+ case MIPS16e_jal_op:
+ addr += 1;
+ if (__get_user(inst2, addr)) {
+ force_sig(SIGSEGV, current);
+ return -EFAULT;
+ }
+ fullinst = ((unsigned)inst.full << 16) | inst2;
+ regs->regs[31] = epc + 6;
+ epc += 4;
+ epc >>= 28;
+ epc <<= 28;
+ /*
+ * JAL:5 X:1 TARGET[20-16]:5 TARGET[25:21]:5 TARGET[15:0]:16
+ *
+ * ......TARGET[15:0].................TARGET[20:16]...........
+ * ......TARGET[25:21]
+ */
+ epc |=
+ ((fullinst & 0xffff) << 2) | ((fullinst & 0x3e00000) >> 3) |
+ ((fullinst & 0x1f0000) << 7);
+ if (!inst.jal.x)
+ set_isa16_mode(epc); /* Set ISA mode bit. */
+ regs->cp0_epc = epc;
+ return 0;
+
+ /*
+ * J(AL)R(C)
+ */
+ case MIPS16e_rr_op:
+ if (inst.rr.func == MIPS16e_jr_func) {
+
+ if (inst.rr.ra)
+ regs->cp0_epc = regs->regs[31];
+ else
+ regs->cp0_epc =
+ regs->regs[reg16to32[inst.rr.rx]];
+
+ if (inst.rr.l) {
+ if (inst.rr.nd)
+ regs->regs[31] = epc + 2;
+ else
+ regs->regs[31] = epc + 4;
+ }
+ return 0;
+ }
+ break;
+ }
+
+ /*
+ * All other cases have no branch delay slot and are 16-bits.
+ * Branches do not cause an exception.
+ */
+ regs->cp0_epc += 2;
+
+ return 0;
+}
+
+/**
+ * __compute_return_epc_for_insn - Computes the return address and do emulate
+ * branch simulation, if required.
+ *
+ * @regs: Pointer to pt_regs
+ * @insn: branch instruction to decode
+ * @returns: -EFAULT on error and forces SIGBUS, and on success
+ * returns 0 or BRANCH_LIKELY_TAKEN as appropriate after
+ * evaluating the branch.
+ */
+int __compute_return_epc_for_insn(struct pt_regs *regs,
+ union mips_instruction insn)
+{
+ unsigned int bit, fcr31, dspcontrol;
+ long epc = regs->cp0_epc;
+ int ret = 0;
+
switch (insn.i_format.opcode) {
/*
* jr and jalr are in r_format format.
@@ -62,20 +429,24 @@ int __compute_return_epc(struct pt_regs *regs)
*/
case bcond_op:
switch (insn.i_format.rt) {
- case bltz_op:
+ case bltz_op:
case bltzl_op:
- if ((long)regs->regs[insn.i_format.rs] < 0)
+ if ((long)regs->regs[insn.i_format.rs] < 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == bltzl_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
case bgez_op:
case bgezl_op:
- if ((long)regs->regs[insn.i_format.rs] >= 0)
+ if ((long)regs->regs[insn.i_format.rs] >= 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == bgezl_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -83,9 +454,11 @@ int __compute_return_epc(struct pt_regs *regs)
case bltzal_op:
case bltzall_op:
regs->regs[31] = epc + 8;
- if ((long)regs->regs[insn.i_format.rs] < 0)
+ if ((long)regs->regs[insn.i_format.rs] < 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == bltzall_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -93,12 +466,15 @@ int __compute_return_epc(struct pt_regs *regs)
case bgezal_op:
case bgezall_op:
regs->regs[31] = epc + 8;
- if ((long)regs->regs[insn.i_format.rs] >= 0)
+ if ((long)regs->regs[insn.i_format.rs] >= 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == bgezall_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
+
case bposge32_op:
if (!cpu_has_dsp)
goto sigill;
@@ -125,6 +501,8 @@ int __compute_return_epc(struct pt_regs *regs)
epc <<= 28;
epc |= (insn.j_format.target << 2);
regs->cp0_epc = epc;
+ if (insn.i_format.opcode == jalx_op)
+ set_isa16_mode(regs->cp0_epc);
break;
/*
@@ -133,9 +511,11 @@ int __compute_return_epc(struct pt_regs *regs)
case beq_op:
case beql_op:
if (regs->regs[insn.i_format.rs] ==
- regs->regs[insn.i_format.rt])
+ regs->regs[insn.i_format.rt]) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.opcode == beql_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -143,9 +523,11 @@ int __compute_return_epc(struct pt_regs *regs)
case bne_op:
case bnel_op:
if (regs->regs[insn.i_format.rs] !=
- regs->regs[insn.i_format.rt])
+ regs->regs[insn.i_format.rt]) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.opcode == bnel_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -153,9 +535,11 @@ int __compute_return_epc(struct pt_regs *regs)
case blez_op: /* not really i_format */
case blezl_op:
/* rt field assumed to be zero */
- if ((long)regs->regs[insn.i_format.rs] <= 0)
+ if ((long)regs->regs[insn.i_format.rs] <= 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.opcode == blezl_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -163,9 +547,11 @@ int __compute_return_epc(struct pt_regs *regs)
case bgtz_op:
case bgtzl_op:
/* rt field assumed to be zero */
- if ((long)regs->regs[insn.i_format.rs] > 0)
+ if ((long)regs->regs[insn.i_format.rs] > 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.opcode == bgtzl_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -176,7 +562,11 @@ int __compute_return_epc(struct pt_regs *regs)
case cop1_op:
preempt_disable();
if (is_fpu_owner())
- asm volatile("cfc1\t%0,$31" : "=r" (fcr31));
+ asm volatile(
+ ".set push\n"
+ "\t.set mips1\n"
+ "\tcfc1\t%0,$31\n"
+ "\t.set pop" : "=r" (fcr31));
else
fcr31 = current->thread.fpu.fcr31;
preempt_enable();
@@ -185,20 +575,24 @@ int __compute_return_epc(struct pt_regs *regs)
bit += (bit != 0);
bit += 23;
switch (insn.i_format.rt & 3) {
- case 0: /* bc1f */
- case 2: /* bc1fl */
- if (~fcr31 & (1 << bit))
+ case 0: /* bc1f */
+ case 2: /* bc1fl */
+ if (~fcr31 & (1 << bit)) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == 2)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
- case 1: /* bc1t */
- case 3: /* bc1tl */
- if (fcr31 & (1 << bit))
+ case 1: /* bc1t */
+ case 3: /* bc1tl */
+ if (fcr31 & (1 << bit)) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == 3)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -239,15 +633,38 @@ int __compute_return_epc(struct pt_regs *regs)
#endif
}
- return 0;
+ return ret;
-unaligned:
- printk("%s: unaligned epc - sending SIGBUS.\n", current->comm);
+sigill:
+ printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm);
force_sig(SIGBUS, current);
return -EFAULT;
+}
+EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn);
-sigill:
- printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm);
+int __compute_return_epc(struct pt_regs *regs)
+{
+ unsigned int __user *addr;
+ long epc;
+ union mips_instruction insn;
+
+ epc = regs->cp0_epc;
+ if (epc & 3)
+ goto unaligned;
+
+ /*
+ * Read the instruction
+ */
+ addr = (unsigned int __user *) epc;
+ if (__get_user(insn.word, addr)) {
+ force_sig(SIGSEGV, current);
+ return -EFAULT;
+ }
+
+ return __compute_return_epc_for_insn(regs, insn);
+
+unaligned:
+ printk("%s: unaligned epc - sending SIGBUS.\n", current->comm);
force_sig(SIGBUS, current);
return -EFAULT;
}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-11-04 01:20:27 +0000