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[arm] Don't allow use of SP as a scratch register

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This would allow SP to be a nonsense value, which would confuse the CPU
profiler when the signal handler read the SP before it was restored.

Bug: v8:8355
Change-Id: If108c8cf00467904fe0f4f26fddc2e3122afcd93
Reviewed-on: https://chromium-review.googlesource.com/c/1298032
Reviewed-by: Martyn Capewell <martyn.capewell@arm.com>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56967}
This commit is contained in:
Peter Marshall 2018-10-24 17:20:36 +02:00 committed by Commit Bot
parent 840242f4c4
commit f16c5f8dd1
1 changed files with 11 additions and 8 deletions
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19
src/arm/assembler-arm.cc
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@ -1167,7 +1167,7 @@ void Assembler::Move32BitImmediate(Register rd, const Operand& x,
DCHECK(!x.MustOutputRelocInfo(this));
UseScratchRegisterScope temps(this);
// Re-use the destination register as a scratch if possible.
Register target = rd != pc ? rd : temps.Acquire();
Register target = rd != pc && rd != sp ? rd : temps.Acquire();
uint32_t imm32 = static_cast<uint32_t>(x.immediate());
movw(target, imm32 & 0xFFFF, cond);
movt(target, imm32 >> 16, cond);
@ -1241,8 +1241,9 @@ void Assembler::AddrMode1(Instr instr, Register rd, Register rn,
// it first to a scratch register and change the original instruction to
// use it.
// Re-use the destination register if possible.
Register scratch =
(rd.is_valid() && rd != rn && rd != pc) ? rd : temps.Acquire();
Register scratch = (rd.is_valid() && rd != rn && rd != pc && rd != sp)
? rd
: temps.Acquire();
mov(scratch, x, LeaveCC, cond);
AddrMode1(instr, rd, rn, Operand(scratch));
}
@ -1307,8 +1308,9 @@ void Assembler::AddrMode2(Instr instr, Register rd, const MemOperand& x) {
UseScratchRegisterScope temps(this);
// Allow re-using rd for load instructions if possible.
bool is_load = (instr & L) == L;
Register scratch =
(is_load && rd != x.rn_ && rd != pc) ? rd : temps.Acquire();
Register scratch = (is_load && rd != x.rn_ && rd != pc && rd != sp)
? rd
: temps.Acquire();
mov(scratch, Operand(x.offset_), LeaveCC,
Instruction::ConditionField(instr));
AddrMode2(instr, rd, MemOperand(x.rn_, scratch, x.am_));
@ -1347,8 +1349,9 @@ void Assembler::AddrMode3(Instr instr, Register rd, const MemOperand& x) {
// register.
UseScratchRegisterScope temps(this);
// Allow re-using rd for load instructions if possible.
Register scratch =
(is_load && rd != x.rn_ && rd != pc) ? rd : temps.Acquire();
Register scratch = (is_load && rd != x.rn_ && rd != pc && rd != sp)
? rd
: temps.Acquire();
mov(scratch, Operand(x.offset_), LeaveCC,
Instruction::ConditionField(instr));
AddrMode3(instr, rd, MemOperand(x.rn_, scratch, x.am_));
@ -1362,7 +1365,7 @@ void Assembler::AddrMode3(Instr instr, Register rd, const MemOperand& x) {
UseScratchRegisterScope temps(this);
// Allow re-using rd for load instructions if possible.
Register scratch =
(is_load && rd != x.rn_ && rd != pc) ? rd : temps.Acquire();
(is_load && rd != x.rn_ && rd != pc && rd != sp) ? rd : temps.Acquire();
mov(scratch, Operand(x.rm_, x.shift_op_, x.shift_imm_), LeaveCC,
Instruction::ConditionField(instr));
AddrMode3(instr, rd, MemOperand(x.rn_, scratch, x.am_));