diff options
| author | Maciej W. Rozycki <macro@imgtec.com> | 2016-01-22 05:21:00 +0000 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2016-01-24 01:36:10 +0100 |
| commit | 69a1e6cbdf1f40d5dcae84c5a538d390b6d2c307 (patch) | |
| tree | 5cfd41a53625d104620bb267345d0ecac2798f8a /arch/mips/math-emu/dsemul.c | |
| parent | 733b8bc183f491e8263009edf8ef184fb44a6882 (diff) | |
MIPS: math-emu: Correct the emulation of microMIPS ADDIUPC instruction
Emulate the microMIPS ADDIUPC instruction directly in `mips_dsemul'. If
executed in the emulation frame, this instruction produces an incorrect
result, because the value of the PC there is not the same as where the
instruction originated.
Reshape code so as to handle all microMIPS cases together.
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12175/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/math-emu/dsemul.c')
| -rw-r--r-- | arch/mips/math-emu/dsemul.c | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/arch/mips/math-emu/dsemul.c b/arch/mips/math-emu/dsemul.c index 32ec5d7e1728..77a623db3b38 100644 --- a/arch/mips/math-emu/dsemul.c +++ b/arch/mips/math-emu/dsemul.c @@ -43,10 +43,30 @@ int mips_dsemul(struct pt_regs *regs, mips_instruction ir, unsigned long cpc) int err; /* NOP is easy */ - if ((get_isa16_mode(regs->cp0_epc) && ((ir >> 16) == MM_NOP16)) || - (ir == 0)) + if (ir == 0) return -1; + /* microMIPS instructions */ + if (get_isa16_mode(regs->cp0_epc)) { + union mips_instruction insn = { .word = ir }; + + /* NOP16 aka MOVE16 $0, $0 */ + if ((ir >> 16) == MM_NOP16) + return -1; + + /* ADDIUPC */ + if (insn.mm_a_format.opcode == mm_addiupc_op) { + unsigned int rs; + s32 v; + + rs = (((insn.mm_a_format.rs + 0x1e) & 0xf) + 2); + v = regs->cp0_epc & ~3; + v += insn.mm_a_format.simmediate << 2; + regs->regs[rs] = (long)v; + return -1; + } + } + pr_debug("dsemul %lx %lx\n", regs->cp0_epc, cpc); /* |