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android_kernel_xiaomi_sm8350/arch/mips/kernel/branch.c
Nathan Chancellor c2869aafe7
MIPS: Don't use bc_false uninitialized in __mm_isBranchInstr 
clang warns:

arch/mips/kernel/branch.c:148:8: error: variable 'bc_false' is used
uninitialized whenever switch case is taken
[-Werror,-Wsometimes-uninitialized]
                case mm_bc2t_op:
                     ^~~~~~~~~~
arch/mips/kernel/branch.c:157:8: note: uninitialized use occurs here
                        if (bc_false)
                            ^~~~~~~~
arch/mips/kernel/branch.c:149:8: error: variable 'bc_false' is used
uninitialized whenever switch case is taken
[-Werror,-Wsometimes-uninitialized]
                case mm_bc1t_op:
                     ^~~~~~~~~~
arch/mips/kernel/branch.c:157:8: note: uninitialized use occurs here
                        if (bc_false)
                            ^~~~~~~~
arch/mips/kernel/branch.c:142:4: note: variable 'bc_false' is declared
here
                        int bc_false = 0;
                        ^
2 errors generated.

When mm_bc1t_op and mm_bc2t_op are taken, the bc_false initialization
does not happen, which leads to a garbage value upon use, as illustrated
below with a small sample program.

$ mipsel-linux-gnu-gcc --version | head -n1
mipsel-linux-gnu-gcc (Debian 8.3.0-2) 8.3.0

$ clang --version | head -n1
ClangBuiltLinux clang version 9.0.0 (git://github.com/llvm/llvm-project
544315b4197034a3be8acd12cba56a75fb1f08dc) (based on LLVM 9.0.0svn)

$ cat test.c
 #include <stdio.h>

 static void switch_scoped(int opcode)
 {
	 switch (opcode) {
	 case 1:
	 case 2: {
		 int bc_false = 0;

		 bc_false = 4;
	 case 3:
	 case 4:
		 printf("\t* switch scoped bc_false = %d\n", bc_false);
	 }
	 }
 }

 static void function_scoped(int opcode)
 {
	 int bc_false = 0;

	 switch (opcode) {
	 case 1:
	 case 2: {
		 bc_false = 4;
	 case 3:
	 case 4:
		 printf("\t* function scoped bc_false = %d\n", bc_false);
	 }
	 }
 }

 int main(void)
 {
	 int opcode;

	 for (opcode = 1; opcode < 5; opcode++) {
		 printf("opcode = %d:\n", opcode);
		 switch_scoped(opcode);
		 function_scoped(opcode);
		 printf("\n");
	 }

	 return 0;
 }

$ mipsel-linux-gnu-gcc -std=gnu89 -static test.c && \
  qemu-mipsel a.out
opcode = 1:
        * switch scoped bc_false = 4
        * function scoped bc_false = 4

opcode = 2:
        * switch scoped bc_false = 4
        * function scoped bc_false = 4

opcode = 3:
        * switch scoped bc_false = 2147483004
        * function scoped bc_false = 0

opcode = 4:
        * switch scoped bc_false = 2147483004
        * function scoped bc_false = 0

$ clang -std=gnu89 --target=mipsel-linux-gnu -m32 -static test.c && \
  qemu-mipsel a.out
opcode = 1:
        * switch scoped bc_false = 4
        * function scoped bc_false = 4

opcode = 2:
        * switch scoped bc_false = 4
        * function scoped bc_false = 4

opcode = 3:
        * switch scoped bc_false = 2147483004
        * function scoped bc_false = 0

opcode = 4:
        * switch scoped bc_false = 2147483004
        * function scoped bc_false = 0

Move the definition up so that we get the right behavior and mark it
__maybe_unused as it will not be used when CONFIG_MIPS_FP_SUPPORT
isn't enabled.

Fixes: 6a1cc218b9 ("MIPS: branch: Remove FP branch handling when CONFIG_MIPS_FP_SUPPORT=n")
Link: https://github.com/ClangBuiltLinux/linux/issues/603
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: clang-built-linux@googlegroups.com
2019-08-11 21:44:24 -07:00

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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1996, 97, 2000, 2001 by Ralf Baechle
* Copyright (C) 2001 MIPS Technologies, Inc.
*/
#include <linux/kernel.h>
#include <linux/sched/signal.h>
#include <linux/signal.h>
#include <linux/export.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/mips-r2-to-r6-emul.h>
#include <asm/ptrace.h>
#include <linux/uaccess.h>
/*
* Calculate and return exception PC in case of branch delay slot
* for microMIPS and MIPS16e. It does not clear the ISA mode bit.
*/
int __isa_exception_epc(struct pt_regs *regs)
{
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);
return epc;
}
if (cpu_has_mips16) {
union mips16e_instruction inst_mips16e;
inst_mips16e.full = inst;
if (inst_mips16e.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 __maybe_unused bc_false = 0;
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;
#ifdef CONFIG_MIPS_FP_SUPPORT
case mm_bc2f_op:
case mm_bc1f_op: {
unsigned int fcr31;
unsigned int bit;
bc_false = 1;
/* Fall through */
case mm_bc2t_op:
case mm_bc1t_op:
preempt_disable();
if (is_fpu_owner())
fcr31 = read_32bit_cp1_register(CP1_STATUS);
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;
}
#endif /* CONFIG_MIPS_FP_SUPPORT */
}
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);
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;
epc = regs->cp0_epc;
/* Read the instruction. */
addr = (u16 __user *)msk_isa16_mode(epc);
if (__get_user(inst.full, addr)) {
force_sig(SIGSEGV);
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);
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
* Return: -EFAULT on error and forces SIGILL, and on success
* returns 0 or BRANCH_LIKELY_TAKEN as appropriate after
* evaluating the branch.
*
* MIPS R6 Compact branches and forbidden slots:
* Compact branches do not throw exceptions because they do
* not have delay slots. The forbidden slot instruction ($PC+4)
* is only executed if the branch was not taken. Otherwise the
* forbidden slot is skipped entirely. This means that the
* only possible reason to be here because of a MIPS R6 compact
* branch instruction is that the forbidden slot has thrown one.
* In that case the branch was not taken, so the EPC can be safely
* set to EPC + 8.
*/
int __compute_return_epc_for_insn(struct pt_regs *regs,
union mips_instruction insn)
{
long epc = regs->cp0_epc;
unsigned int dspcontrol;
int ret = 0;
switch (insn.i_format.opcode) {
/*
* jr and jalr are in r_format format.
*/
case spec_op:
switch (insn.r_format.func) {
case jalr_op:
regs->regs[insn.r_format.rd] = epc + 8;
/* Fall through */
case jr_op:
if (NO_R6EMU && insn.r_format.func == jr_op)
goto sigill_r2r6;
regs->cp0_epc = regs->regs[insn.r_format.rs];
break;
}
break;
/*
* This group contains:
* bltz_op, bgez_op, bltzl_op, bgezl_op,
* bltzal_op, bgezal_op, bltzall_op, bgezall_op.
*/
case bcond_op:
switch (insn.i_format.rt) {
case bltzl_op:
if (NO_R6EMU)
goto sigill_r2r6;
/* fall through */
case bltz_op:
if ((long)regs->regs[insn.i_format.rs] < 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
if (insn.i_format.rt == bltzl_op)
ret = BRANCH_LIKELY_TAKEN;
} else
epc += 8;
regs->cp0_epc = epc;
break;
case bgezl_op:
if (NO_R6EMU)
goto sigill_r2r6;
/* fall through */
case bgez_op:
if ((long)regs->regs[insn.i_format.rs] >= 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
if (insn.i_format.rt == bgezl_op)
ret = BRANCH_LIKELY_TAKEN;
} else
epc += 8;
regs->cp0_epc = epc;
break;
case bltzal_op:
case bltzall_op:
if (NO_R6EMU && (insn.i_format.rs ||
insn.i_format.rt == bltzall_op))
goto sigill_r2r6;
regs->regs[31] = epc + 8;
/*
* OK we are here either because we hit a NAL
* instruction or because we are emulating an
* old bltzal{,l} one. Let's figure out what the
* case really is.
*/
if (!insn.i_format.rs) {
/*
* NAL or BLTZAL with rs == 0
* Doesn't matter if we are R6 or not. The
* result is the same
*/
regs->cp0_epc += 4 +
(insn.i_format.simmediate << 2);
break;
}
/* Now do the real thing for non-R6 BLTZAL{,L} */
if ((long)regs->regs[insn.i_format.rs] < 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
if (insn.i_format.rt == bltzall_op)
ret = BRANCH_LIKELY_TAKEN;
} else
epc += 8;
regs->cp0_epc = epc;
break;
case bgezal_op:
case bgezall_op:
if (NO_R6EMU && (insn.i_format.rs ||
insn.i_format.rt == bgezall_op))
goto sigill_r2r6;
regs->regs[31] = epc + 8;
/*
* OK we are here either because we hit a BAL
* instruction or because we are emulating an
* old bgezal{,l} one. Let's figure out what the
* case really is.
*/
if (!insn.i_format.rs) {
/*
* BAL or BGEZAL with rs == 0
* Doesn't matter if we are R6 or not. The
* result is the same
*/
regs->cp0_epc += 4 +
(insn.i_format.simmediate << 2);
break;
}
/* Now do the real thing for non-R6 BGEZAL{,L} */
if ((long)regs->regs[insn.i_format.rs] >= 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
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_dsp;
dspcontrol = rddsp(0x01);
if (dspcontrol >= 32) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
} else
epc += 8;
regs->cp0_epc = epc;
break;
}
break;
/*
* These are unconditional and in j_format.
*/
case jalx_op:
case jal_op:
regs->regs[31] = regs->cp0_epc + 8;
/* fall through */
case j_op:
epc += 4;
epc >>= 28;
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;
/*
* These are conditional and in i_format.
*/
case beql_op:
if (NO_R6EMU)
goto sigill_r2r6;
/* fall through */
case beq_op:
if (regs->regs[insn.i_format.rs] ==
regs->regs[insn.i_format.rt]) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
if (insn.i_format.opcode == beql_op)
ret = BRANCH_LIKELY_TAKEN;
} else
epc += 8;
regs->cp0_epc = epc;
break;
case bnel_op:
if (NO_R6EMU)
goto sigill_r2r6;
/* fall through */
case bne_op:
if (regs->regs[insn.i_format.rs] !=
regs->regs[insn.i_format.rt]) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
if (insn.i_format.opcode == bnel_op)
ret = BRANCH_LIKELY_TAKEN;
} else
epc += 8;
regs->cp0_epc = epc;
break;
case blezl_op: /* not really i_format */
if (!insn.i_format.rt && NO_R6EMU)
goto sigill_r2r6;
/* fall through */
case blez_op:
/*
* Compact branches for R6 for the
* blez and blezl opcodes.
* BLEZ | rs = 0 | rt != 0 == BLEZALC
* BLEZ | rs = rt != 0 == BGEZALC
* BLEZ | rs != 0 | rt != 0 == BGEUC
* BLEZL | rs = 0 | rt != 0 == BLEZC
* BLEZL | rs = rt != 0 == BGEZC
* BLEZL | rs != 0 | rt != 0 == BGEC
*
* For real BLEZ{,L}, rt is always 0.
*/
if (cpu_has_mips_r6 && insn.i_format.rt) {
if ((insn.i_format.opcode == blez_op) &&
((!insn.i_format.rs && insn.i_format.rt) ||
(insn.i_format.rs == insn.i_format.rt)))
regs->regs[31] = epc + 4;
regs->cp0_epc += 8;
break;
}
/* rt field assumed to be zero */
if ((long)regs->regs[insn.i_format.rs] <= 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
if (insn.i_format.opcode == blezl_op)
ret = BRANCH_LIKELY_TAKEN;
} else
epc += 8;
regs->cp0_epc = epc;
break;
case bgtzl_op:
if (!insn.i_format.rt && NO_R6EMU)
goto sigill_r2r6;
/* fall through */
case bgtz_op:
/*
* Compact branches for R6 for the
* bgtz and bgtzl opcodes.
* BGTZ | rs = 0 | rt != 0 == BGTZALC
* BGTZ | rs = rt != 0 == BLTZALC
* BGTZ | rs != 0 | rt != 0 == BLTUC
* BGTZL | rs = 0 | rt != 0 == BGTZC
* BGTZL | rs = rt != 0 == BLTZC
* BGTZL | rs != 0 | rt != 0 == BLTC
*
* *ZALC varint for BGTZ &&& rt != 0
* For real GTZ{,L}, rt is always 0.
*/
if (cpu_has_mips_r6 && insn.i_format.rt) {
if ((insn.i_format.opcode == blez_op) &&
((!insn.i_format.rs && insn.i_format.rt) ||
(insn.i_format.rs == insn.i_format.rt)))
regs->regs[31] = epc + 4;
regs->cp0_epc += 8;
break;
}
/* rt field assumed to be zero */
if ((long)regs->regs[insn.i_format.rs] > 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
if (insn.i_format.opcode == bgtzl_op)
ret = BRANCH_LIKELY_TAKEN;
} else
epc += 8;
regs->cp0_epc = epc;
break;
#ifdef CONFIG_MIPS_FP_SUPPORT
/*
* And now the FPA/cp1 branch instructions.
*/
case cop1_op: {
unsigned int bit, fcr31, reg;
if (cpu_has_mips_r6 &&
((insn.i_format.rs == bc1eqz_op) ||
(insn.i_format.rs == bc1nez_op))) {
if (!init_fp_ctx(current))
lose_fpu(1);
reg = insn.i_format.rt;
bit = get_fpr32(&current->thread.fpu.fpr[reg], 0) & 0x1;
if (insn.i_format.rs == bc1eqz_op)
bit = !bit;
own_fpu(1);
if (bit)
epc = epc + 4 +
(insn.i_format.simmediate << 2);
else
epc += 8;
regs->cp0_epc = epc;
break;
} else {
preempt_disable();
if (is_fpu_owner())
fcr31 = read_32bit_cp1_register(CP1_STATUS);
else
fcr31 = current->thread.fpu.fcr31;
preempt_enable();
bit = (insn.i_format.rt >> 2);
bit += (bit != 0);
bit += 23;
switch (insn.i_format.rt & 3) {
case 0: /* bc1f */
case 2: /* bc1fl */
if (~fcr31 & (1 << bit)) {
epc = epc + 4 +
(insn.i_format.simmediate << 2);
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)) {
epc = epc + 4 +
(insn.i_format.simmediate << 2);
if (insn.i_format.rt == 3)
ret = BRANCH_LIKELY_TAKEN;
} else
epc += 8;
regs->cp0_epc = epc;
break;
}
break;
}
}
#endif /* CONFIG_MIPS_FP_SUPPORT */
#ifdef CONFIG_CPU_CAVIUM_OCTEON
case lwc2_op: /* This is bbit0 on Octeon */
if ((regs->regs[insn.i_format.rs] & (1ull<<insn.i_format.rt))
== 0)
epc = epc + 4 + (insn.i_format.simmediate << 2);
else
epc += 8;
regs->cp0_epc = epc;
break;
case ldc2_op: /* This is bbit032 on Octeon */
if ((regs->regs[insn.i_format.rs] &
(1ull<<(insn.i_format.rt+32))) == 0)
epc = epc + 4 + (insn.i_format.simmediate << 2);
else
epc += 8;
regs->cp0_epc = epc;
break;
case swc2_op: /* This is bbit1 on Octeon */
if (regs->regs[insn.i_format.rs] & (1ull<<insn.i_format.rt))
epc = epc + 4 + (insn.i_format.simmediate << 2);
else
epc += 8;
regs->cp0_epc = epc;
break;
case sdc2_op: /* This is bbit132 on Octeon */
if (regs->regs[insn.i_format.rs] &
(1ull<<(insn.i_format.rt+32)))
epc = epc + 4 + (insn.i_format.simmediate << 2);
else
epc += 8;
regs->cp0_epc = epc;
break;
#else
case bc6_op:
/* Only valid for MIPS R6 */
if (!cpu_has_mips_r6)
goto sigill_r6;
regs->cp0_epc += 8;
break;
case balc6_op:
if (!cpu_has_mips_r6)
goto sigill_r6;
/* Compact branch: BALC */
regs->regs[31] = epc + 4;
epc += 4 + (insn.i_format.simmediate << 2);
regs->cp0_epc = epc;
break;
case pop66_op:
if (!cpu_has_mips_r6)
goto sigill_r6;
/* Compact branch: BEQZC || JIC */
regs->cp0_epc += 8;
break;
case pop76_op:
if (!cpu_has_mips_r6)
goto sigill_r6;
/* Compact branch: BNEZC || JIALC */
if (!insn.i_format.rs) {
/* JIALC: set $31/ra */
regs->regs[31] = epc + 4;
}
regs->cp0_epc += 8;
break;
#endif
case pop10_op:
case pop30_op:
/* Only valid for MIPS R6 */
if (!cpu_has_mips_r6)
goto sigill_r6;
/*
* Compact branches:
* bovc, beqc, beqzalc, bnvc, bnec, bnezlac
*/
if (insn.i_format.rt && !insn.i_format.rs)
regs->regs[31] = epc + 4;
regs->cp0_epc += 8;
break;
}
return ret;
sigill_dsp:
pr_debug("%s: DSP branch but not DSP ASE - sending SIGILL.\n",
current->comm);
force_sig(SIGILL);
return -EFAULT;
sigill_r2r6:
pr_debug("%s: R2 branch but r2-to-r6 emulator is not present - sending SIGILL.\n",
current->comm);
force_sig(SIGILL);
return -EFAULT;
sigill_r6:
pr_debug("%s: R6 branch but no MIPSr6 ISA support - sending SIGILL.\n",
current->comm);
force_sig(SIGILL);
return -EFAULT;
}
EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn);
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);
return -EFAULT;
}
return __compute_return_epc_for_insn(regs, insn);
unaligned:
printk("%s: unaligned epc - sending SIGBUS.\n", current->comm);
force_sig(SIGBUS);
return -EFAULT;
}
#if (defined CONFIG_KPROBES) || (defined CONFIG_UPROBES)
int __insn_is_compact_branch(union mips_instruction insn)
{
if (!cpu_has_mips_r6)
return 0;
switch (insn.i_format.opcode) {
case blezl_op:
case bgtzl_op:
case blez_op:
case bgtz_op:
/*
* blez[l] and bgtz[l] opcodes with non-zero rt
* are MIPS R6 compact branches
*/
if (insn.i_format.rt)
return 1;
break;
case bc6_op:
case balc6_op:
case pop10_op:
case pop30_op:
case pop66_op:
case pop76_op:
return 1;
}
return 0;
}
EXPORT_SYMBOL_GPL(__insn_is_compact_branch);
#endif /* CONFIG_KPROBES || CONFIG_UPROBES */
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