Add emulation/spoofing of SLDT and STR for both 32- and 64-bit processes. Wine users have found a small number of Windows apps using SLDT that were crashing when run on UMIP-enabled systems.
Reported-by: Andreas Rammhold <andi@notmuch.email> Originally-by: Ricardo Neri <ricardo.neri-calde...@linux.intel.com> Signed-off-by: Brendan Shanks <bsha...@codeweavers.com> --- arch/x86/kernel/umip.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/umip.c b/arch/x86/kernel/umip.c index 8d5cbe1bbb3b..59dfceac5cc0 100644 --- a/arch/x86/kernel/umip.c +++ b/arch/x86/kernel/umip.c @@ -64,6 +64,8 @@ #define UMIP_DUMMY_GDT_BASE 0xfffffffffffe0000ULL #define UMIP_DUMMY_IDT_BASE 0xffffffffffff0000ULL +#define UMIP_DUMMY_TASK_REGISTER_SELECTOR 0x40 + /* * The SGDT and SIDT instructions store the contents of the global descriptor * table and interrupt table registers, respectively. The destination is a @@ -244,16 +246,24 @@ static int emulate_umip_insn(struct insn *insn, int umip_inst, *data_size += UMIP_GDT_IDT_LIMIT_SIZE; memcpy(data, &dummy_limit, UMIP_GDT_IDT_LIMIT_SIZE); - } else if (umip_inst == UMIP_INST_SMSW) { - unsigned long dummy_value = CR0_STATE; + } else if (umip_inst == UMIP_INST_SMSW || umip_inst == UMIP_INST_SLDT || + umip_inst == UMIP_INST_STR) { + unsigned long dummy_value; + + if (umip_inst == UMIP_INST_SMSW) + dummy_value = CR0_STATE; + else if (umip_inst == UMIP_INST_STR) + dummy_value = UMIP_DUMMY_TASK_REGISTER_SELECTOR; + else + dummy_value = 0; /* - * Even though the CR0 register has 4 bytes, the number + * For these 3 instructions, the number * of bytes to be copied in the result buffer is determined * by whether the operand is a register or a memory location. * If operand is a register, return as many bytes as the operand * size. If operand is memory, return only the two least - * siginificant bytes of CR0. + * siginificant bytes. */ if (X86_MODRM_MOD(insn->modrm.value) == 3) *data_size = insn->opnd_bytes; @@ -261,7 +271,6 @@ static int emulate_umip_insn(struct insn *insn, int umip_inst, *data_size = 2; memcpy(data, &dummy_value, *data_size); - /* STR and SLDT are not emulated */ } else { return -EINVAL; } @@ -383,10 +392,6 @@ bool fixup_umip_exception(struct pt_regs *regs) umip_pr_warn(regs, "%s instruction cannot be used by applications.\n", umip_insns[umip_inst]); - /* Do not emulate (spoof) SLDT or STR. */ - if (umip_inst == UMIP_INST_STR || umip_inst == UMIP_INST_SLDT) - return false; - umip_pr_warn(regs, "For now, expensive software emulation returns the result.\n"); if (emulate_umip_insn(&insn, umip_inst, dummy_data, &dummy_data_size, -- 2.26.2