Commit ea3164aa authored by Kwok Cheung Yeung's avatar Kwok Cheung Yeung Committed by Aurelien Jarno
Browse files

linux-user: Fix MIPS ISA transitions during signal handling 



Processors supporting the MIPS16 or microMIPS ISAs set bit 0 in target
addresses to indicate that the target is written using a compressed ISA.

During signal handling, when jumping to or returning from a signal
handler, bit 0 of the destination PC is inspected and MIPS_HFLAG_M16 in
hflags cleared or set accordingly.  Bit 0 of the PC is then cleared.

Signed-off-by: default avatarKwok Cheung Yeung <kcy@codesourcery.com>
Signed-off-by: default avatarAurelien Jarno <aurelien@aurel32.net>
parent d8992825

linux-user/signal.c

+13 −0
Original line number Diff line number Diff line
@@ -2620,6 +2620,15 @@ get_sigframe(struct target_sigaction *ka, CPUMIPSState *regs, size_t frame_size) 
    return (sp - frame_size) & ~7;

}



static void mips_set_hflags_isa_mode_from_pc(CPUMIPSState *env)

{

    if (env->insn_flags & (ASE_MIPS16 | ASE_MICROMIPS)) {

        env->hflags &= ~MIPS_HFLAG_M16;

        env->hflags |= (env->active_tc.PC & 1) << MIPS_HFLAG_M16_SHIFT;

        env->active_tc.PC &= ~(target_ulong) 1;

    }

}



# if defined(TARGET_ABI_MIPSO32)

/* compare linux/arch/mips/kernel/signal.c:setup_frame() */

static void setup_frame(int sig, struct target_sigaction * ka,
@@ -2662,6 +2671,7 @@ static void setup_frame(int sig, struct target_sigaction * ka, 
    * since it returns to userland using eret

    * we cannot do this here, and we must set PC directly */

    regs->active_tc.PC = regs->active_tc.gpr[25] = ka->_sa_handler;

    mips_set_hflags_isa_mode_from_pc(regs);

    unlock_user_struct(frame, frame_addr, 1);

    return;
@@ -2709,6 +2719,7 @@ long do_sigreturn(CPUMIPSState *regs) 
#endif



    regs->active_tc.PC = regs->CP0_EPC;

    mips_set_hflags_isa_mode_from_pc(regs);

    /* I am not sure this is right, but it seems to work

    * maybe a problem with nested signals ? */

    regs->CP0_EPC = 0;
@@ -2771,6 +2782,7 @@ static void setup_rt_frame(int sig, struct target_sigaction *ka, 
    * since it returns to userland using eret

    * we cannot do this here, and we must set PC directly */

    env->active_tc.PC = env->active_tc.gpr[25] = ka->_sa_handler;

    mips_set_hflags_isa_mode_from_pc(env);

    unlock_user_struct(frame, frame_addr, 1);

    return;
@@ -2804,6 +2816,7 @@ long do_rt_sigreturn(CPUMIPSState *env) 
        goto badframe;



    env->active_tc.PC = env->CP0_EPC;

    mips_set_hflags_isa_mode_from_pc(env);

    /* I am not sure this is right, but it seems to work

    * maybe a problem with nested signals ? */

    env->CP0_EPC = 0;