powerpc: Fix VRSAVE handling

Since 2002, the kernel has not saved VRSAVE on exception entry and
restored it on exit; rather, VRSAVE gets context-switched in _switch.
This means that when executing in process context in the kernel, the
userspace VRSAVE value is live in the VRSAVE register.

However, the signal code assumes that current->thread.vrsave holds
the current VRSAVE value, which is incorrect.  Therefore, this
commit changes it to use the actual VRSAVE register instead.  (It
still uses current->thread.vrsave as a temporary location to store
it in, as __get_user and __put_user can only transfer to/from a
variable, not an SPR.)

This also modifies the transactional memory code to save and restore
VRSAVE regardless of whether VMX is enabled in the MSR.  This is
because accesses to VRSAVE are not controlled by the MSR.VEC bit,
but can happen at any time.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 0f83122e6676cf8dd8692d3e64f72a2c961f34bb..bebdf1a1a5403df741ea389102f1b69b80daf60e 100644 (file)
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -436,7 +436,10 @@ static int save_user_regs(struct pt_regs *regs, struct mcontext __user *frame,
         * use altivec. Since VSCR only contains 32 bits saved in the least
         * significant bits of a vector, we "cheat" and stuff VRSAVE in the
         * most significant bits of that same vector. --BenH
+        * Note that the current VRSAVE value is in the SPR at this point.
         */
+       if (cpu_has_feature(CPU_FTR_ALTIVEC))
+               current->thread.vrsave = mfspr(SPRN_VRSAVE);
        if (__put_user(current->thread.vrsave, (u32 __user *)&frame->mc_vregs[32]))
                return 1;
 #endif /* CONFIG_ALTIVEC */
@@ -557,6 +560,8 @@ static int save_tm_user_regs(struct pt_regs *regs,
         * significant bits of a vector, we "cheat" and stuff VRSAVE in the
         * most significant bits of that same vector. --BenH
         */
+       if (cpu_has_feature(CPU_FTR_ALTIVEC))
+               current->thread.vrsave = mfspr(SPRN_VRSAVE);
        if (__put_user(current->thread.vrsave,
                       (u32 __user *)&frame->mc_vregs[32]))
                return 1;
@@ -696,6 +701,8 @@ static long restore_user_regs(struct pt_regs *regs,
        /* Always get VRSAVE back */
        if (__get_user(current->thread.vrsave, (u32 __user *)&sr->mc_vregs[32]))
                return 1;
+       if (cpu_has_feature(CPU_FTR_ALTIVEC))
+               mtspr(SPRN_VRSAVE, current->thread.vrsave);
 #endif /* CONFIG_ALTIVEC */
        if (copy_fpr_from_user(current, &sr->mc_fregs))
                return 1;
@@ -809,6 +816,8 @@ static long restore_tm_user_regs(struct pt_regs *regs,
            __get_user(current->thread.transact_vrsave,
                       (u32 __user *)&tm_sr->mc_vregs[32]))
                return 1;
+       if (cpu_has_feature(CPU_FTR_ALTIVEC))
+               mtspr(SPRN_VRSAVE, current->thread.vrsave);
 #endif /* CONFIG_ALTIVEC */
 
        regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1);

diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index cbd26928e04d11633335ba9216d673dde7a02a20..d0106b8a748431152dbbf0304ec1e7c9b06b53d9 100644 (file)
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -114,6 +114,8 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
        /* We always copy to/from vrsave, it's 0 if we don't have or don't
         * use altivec.
         */
+       if (cpu_has_feature(CPU_FTR_ALTIVEC))
+               current->thread.vrsave = mfspr(SPRN_VRSAVE);
        err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
 #else /* CONFIG_ALTIVEC */
        err |= __put_user(0, &sc->v_regs);
@@ -217,6 +219,8 @@ static long setup_tm_sigcontexts(struct sigcontext __user *sc,
        /* We always copy to/from vrsave, it's 0 if we don't have or don't
         * use altivec.
         */
+       if (cpu_has_feature(CPU_FTR_ALTIVEC))
+               current->thread.vrsave = mfspr(SPRN_VRSAVE);
        err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
        if (msr & MSR_VEC)
                err |= __put_user(current->thread.transact_vrsave,
@@ -356,6 +360,8 @@ static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
                err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
        else
                current->thread.vrsave = 0;
+       if (cpu_has_feature(CPU_FTR_ALTIVEC))
+               mtspr(SPRN_VRSAVE, current->thread.vrsave);
 #endif /* CONFIG_ALTIVEC */
        /* restore floating point */
        err |= copy_fpr_from_user(current, &sc->fp_regs);
@@ -484,6 +490,8 @@ static long restore_tm_sigcontexts(struct pt_regs *regs,
                current->thread.vrsave = 0;
                current->thread.transact_vrsave = 0;
        }
+       if (cpu_has_feature(CPU_FTR_ALTIVEC))
+               mtspr(SPRN_VRSAVE, current->thread.vrsave);
 #endif /* CONFIG_ALTIVEC */
        /* restore floating point */
        err |= copy_fpr_from_user(current, &sc->fp_regs);

diff --git a/arch/powerpc/kernel/tm.S b/arch/powerpc/kernel/tm.S
index 51be8fb2480313610b5971b6ef70a89f58f794a2..e2145b222f83ffc092329f9712a0e8c9be1df9ed 100644 (file)
--- a/arch/powerpc/kernel/tm.S
+++ b/arch/powerpc/kernel/tm.S
@@ -155,10 +155,10 @@ _GLOBAL(tm_reclaim)
        mfvscr  vr0
        li      r6, THREAD_TRANSACT_VSCR
        stvx    vr0, r3, r6
+dont_backup_vec:
        mfspr   r0, SPRN_VRSAVE
        std     r0, THREAD_TRANSACT_VRSAVE(r3)
 
-dont_backup_vec:
        andi.   r0, r4, MSR_FP
        beq     dont_backup_fp
 
@@ -331,11 +331,11 @@ _GLOBAL(tm_recheckpoint)
        lvx     vr0, r3, r5
        mtvscr  vr0
        REST_32VRS(0, r5, r3)                   /* r5 scratch, r3 THREAD ptr */
+dont_restore_vec:
        ld      r5, THREAD_VRSAVE(r3)
        mtspr   SPRN_VRSAVE, r5
 #endif
 
-dont_restore_vec:
        andi.   r0, r4, MSR_FP
        beq     dont_restore_fp