sparc64: Make montmul/montsqr/mpmul usable in 32-bit threads.
authorDavid S. Miller <davem@davemloft.net>
Fri, 26 Oct 2012 22:18:37 +0000 (15:18 -0700)
committerDavid S. Miller <davem@davemloft.net>
Fri, 26 Oct 2012 22:18:37 +0000 (15:18 -0700)
The Montgomery Multiply, Montgomery Square, and Multiple-Precision
Multiply instructions work by loading a combination of the floating
point and multiple register windows worth of integer registers
with the inputs.

These values are 64-bit.  But for 32-bit userland processes we only
save the low 32-bits of each integer register during a register spill.
This is because the register window save area is in the user stack and
has a fixed layout.

Therefore, the only way to use these instruction in 32-bit mode is to
perform the following sequence:

1) Load the top-32bits of a choosen integer register with a sentinel,
   say "-1".  This will be in the outer-most register window.

   The idea is that we're trying to see if the outer-most register
   window gets spilled, and thus the 64-bit values were truncated.

2) Load all the inputs for the montmul/montsqr/mpmul instruction,
   down to the inner-most register window.

3) Execute the opcode.

4) Traverse back up to the outer-most register window.

5) Check the sentinel, if it's still "-1" store the results.
   Otherwise retry the entire sequence.

This retry is extremely troublesome.  If you're just unlucky and an
interrupt or other trap happens, it'll push that outer-most window to
the stack and clear the sentinel when we restore it.

We could retry forever and never make forward progress if interrupts
arrive at a fast enough rate (consider perf events as one example).
So we have do limited retries and fallback to software which is
extremely non-deterministic.

Luckily it's very straightforward to provide a mechanism to let
32-bit applications use a 64-bit stack.  Stacks in 64-bit mode are
biased by 2047 bytes, which means that the lowest bit is set in the
actual %sp register value.

So if we see bit zero set in a 32-bit application's stack we treat
it like a 64-bit stack.

Runtime detection of such a facility is tricky, and cumbersome at
best.  For example, just trying to use a biased stack and seeing if it
works is hard to recover from (the signal handler will need to use an
alt stack, plus something along the lines of longjmp).  Therefore, we
add a system call to report a bitmask of arch specific features like
this in a cheap and less hairy way.

With help from Andy Polyakov.

Signed-off-by: David S. Miller <davem@davemloft.net>
13 files changed:
arch/sparc/include/asm/compat.h
arch/sparc/include/asm/thread_info_64.h
arch/sparc/include/asm/ttable.h
arch/sparc/include/uapi/asm/unistd.h
arch/sparc/kernel/perf_event.c
arch/sparc/kernel/process_64.c
arch/sparc/kernel/ptrace_64.c
arch/sparc/kernel/sys_sparc_64.c
arch/sparc/kernel/systbls_64.S
arch/sparc/kernel/unaligned_64.c
arch/sparc/kernel/visemul.c
arch/sparc/kernel/winfixup.S
arch/sparc/math-emu/math_64.c

index cef99fbc0a214b80721029fd826d1733f066868e..830502fe62b4e6a3d334abaf4076a5957deb2d9c 100644 (file)
@@ -232,9 +232,10 @@ static inline void __user *arch_compat_alloc_user_space(long len)
        struct pt_regs *regs = current_thread_info()->kregs;
        unsigned long usp = regs->u_regs[UREG_I6];
 
-       if (!(test_thread_flag(TIF_32BIT)))
+       if (test_thread_64bit_stack(usp))
                usp += STACK_BIAS;
-       else
+
+       if (test_thread_flag(TIF_32BIT))
                usp &= 0xffffffffUL;
 
        usp -= len;
index 4e227663108181b45700b0cb879d5043ee1da64b..a3fe4dcc0aa6c5d25c7fa67ce3c74390b3a01876 100644 (file)
@@ -259,6 +259,11 @@ static inline bool test_and_clear_restore_sigmask(void)
 
 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
 
+#define thread32_stack_is_64bit(__SP) (((__SP) & 0x1) != 0)
+#define test_thread_64bit_stack(__SP) \
+       ((test_thread_flag(TIF_32BIT) && !thread32_stack_is_64bit(__SP)) ? \
+        false : true)
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __KERNEL__ */
index 48f2807d326563da2bc95be4f870517685331aaf..71b5a67522abb2bb0d8457819612aa26e948fdc8 100644 (file)
@@ -372,7 +372,9 @@ etrap_spill_fixup_64bit:                            \
 
 /* Normal 32bit spill */
 #define SPILL_2_GENERIC(ASI)                           \
-       srl     %sp, 0, %sp;                            \
+       and     %sp, 1, %g3;                            \
+       brnz,pn %g3, (. - (128 + 4));                   \
+        srl    %sp, 0, %sp;                            \
        stwa    %l0, [%sp + %g0] ASI;                   \
        mov     0x04, %g3;                              \
        stwa    %l1, [%sp + %g3] ASI;                   \
@@ -398,14 +400,16 @@ etrap_spill_fixup_64bit:                          \
        stwa    %i6, [%g1 + %g0] ASI;                   \
        stwa    %i7, [%g1 + %g3] ASI;                   \
        saved;                                          \
-        retry; nop; nop;                               \
+        retry;                                         \
        b,a,pt  %xcc, spill_fixup_dax;                  \
        b,a,pt  %xcc, spill_fixup_mna;                  \
        b,a,pt  %xcc, spill_fixup;
 
 #define SPILL_2_GENERIC_ETRAP          \
 etrap_user_spill_32bit:                        \
-       srl     %sp, 0, %sp;            \
+       and     %sp, 1, %g3;            \
+       brnz,pn %g3, etrap_user_spill_64bit;    \
+        srl    %sp, 0, %sp;            \
        stwa    %l0, [%sp + 0x00] %asi; \
        stwa    %l1, [%sp + 0x04] %asi; \
        stwa    %l2, [%sp + 0x08] %asi; \
@@ -427,7 +431,7 @@ etrap_user_spill_32bit:                     \
        ba,pt   %xcc, etrap_save;       \
         wrpr   %g1, %cwp;              \
        nop; nop; nop; nop;             \
-       nop; nop; nop; nop;             \
+       nop; nop;                       \
        ba,a,pt %xcc, etrap_spill_fixup_32bit; \
        ba,a,pt %xcc, etrap_spill_fixup_32bit; \
        ba,a,pt %xcc, etrap_spill_fixup_32bit;
@@ -592,7 +596,9 @@ user_rtt_fill_64bit:                                        \
 
 /* Normal 32bit fill */
 #define FILL_2_GENERIC(ASI)                            \
-       srl     %sp, 0, %sp;                            \
+       and     %sp, 1, %g3;                            \
+       brnz,pn %g3, (. - (128 + 4));                   \
+        srl    %sp, 0, %sp;                            \
        lduwa   [%sp + %g0] ASI, %l0;                   \
        mov     0x04, %g2;                              \
        mov     0x08, %g3;                              \
@@ -616,14 +622,16 @@ user_rtt_fill_64bit:                                      \
        lduwa   [%g1 + %g3] ASI, %i6;                   \
        lduwa   [%g1 + %g5] ASI, %i7;                   \
        restored;                                       \
-       retry; nop; nop; nop; nop;                      \
+       retry; nop; nop;                                \
        b,a,pt  %xcc, fill_fixup_dax;                   \
        b,a,pt  %xcc, fill_fixup_mna;                   \
        b,a,pt  %xcc, fill_fixup;
 
 #define FILL_2_GENERIC_RTRAP                           \
 user_rtt_fill_32bit:                                   \
-       srl     %sp, 0, %sp;                            \
+       and     %sp, 1, %g3;                            \
+       brnz,pn %g3, user_rtt_fill_64bit;               \
+        srl    %sp, 0, %sp;                            \
        lduwa   [%sp + 0x00] %asi, %l0;                 \
        lduwa   [%sp + 0x04] %asi, %l1;                 \
        lduwa   [%sp + 0x08] %asi, %l2;                 \
@@ -643,7 +651,7 @@ user_rtt_fill_32bit:                                        \
        ba,pt   %xcc, user_rtt_pre_restore;             \
         restored;                                      \
        nop; nop; nop; nop; nop;                        \
-       nop; nop; nop; nop; nop;                        \
+       nop; nop; nop;                                  \
        ba,a,pt %xcc, user_rtt_fill_fixup;              \
        ba,a,pt %xcc, user_rtt_fill_fixup;              \
        ba,a,pt %xcc, user_rtt_fill_fixup;
index 8974ef7ae920685174f7d6427da816e4d3c7d3db..bed86a820d09adb3802bc69fa89441cd1940347f 100644 (file)
 #define __NR_setns             337
 #define __NR_process_vm_readv  338
 #define __NR_process_vm_writev 339
+#define __NR_kern_features     340
 
-#define NR_syscalls            340
+#define NR_syscalls            341
+
+/* Bitmask values returned from kern_features system call.  */
+#define KERN_FEATURE_MIXED_MODE_STACK  0x00000001
 
 #ifdef __32bit_syscall_numbers__
 /* Sparc 32-bit only has the "setresuid32", "getresuid32" variants,
index 885a8af74064b1425be7e424ca205996c4add704..b5c38faa4eadf423db3bc20df35d2c98cd5dabf3 100644 (file)
@@ -1762,15 +1762,25 @@ static void perf_callchain_user_32(struct perf_callchain_entry *entry,
 
        ufp = regs->u_regs[UREG_I6] & 0xffffffffUL;
        do {
-               struct sparc_stackf32 *usf, sf;
                unsigned long pc;
 
-               usf = (struct sparc_stackf32 *) ufp;
-               if (__copy_from_user_inatomic(&sf, usf, sizeof(sf)))
-                       break;
+               if (thread32_stack_is_64bit(ufp)) {
+                       struct sparc_stackf *usf, sf;
 
-               pc = sf.callers_pc;
-               ufp = (unsigned long)sf.fp;
+                       ufp += STACK_BIAS;
+                       usf = (struct sparc_stackf *) ufp;
+                       if (__copy_from_user_inatomic(&sf, usf, sizeof(sf)))
+                               break;
+                       pc = sf.callers_pc & 0xffffffff;
+                       ufp = ((unsigned long) sf.fp) & 0xffffffff;
+               } else {
+                       struct sparc_stackf32 *usf, sf;
+                       usf = (struct sparc_stackf32 *) ufp;
+                       if (__copy_from_user_inatomic(&sf, usf, sizeof(sf)))
+                               break;
+                       pc = sf.callers_pc;
+                       ufp = (unsigned long)sf.fp;
+               }
                perf_callchain_store(entry, pc);
        } while (entry->nr < PERF_MAX_STACK_DEPTH);
 }
index d778248ef3f8ea7b48de69d0a68ca586e5acfef3..c6e0c2910043556a073ba8e8f11843f09d20ca71 100644 (file)
@@ -452,13 +452,16 @@ void flush_thread(void)
 /* It's a bit more tricky when 64-bit tasks are involved... */
 static unsigned long clone_stackframe(unsigned long csp, unsigned long psp)
 {
+       bool stack_64bit = test_thread_64bit_stack(psp);
        unsigned long fp, distance, rval;
 
-       if (!(test_thread_flag(TIF_32BIT))) {
+       if (stack_64bit) {
                csp += STACK_BIAS;
                psp += STACK_BIAS;
                __get_user(fp, &(((struct reg_window __user *)psp)->ins[6]));
                fp += STACK_BIAS;
+               if (test_thread_flag(TIF_32BIT))
+                       fp &= 0xffffffff;
        } else
                __get_user(fp, &(((struct reg_window32 __user *)psp)->ins[6]));
 
@@ -472,7 +475,7 @@ static unsigned long clone_stackframe(unsigned long csp, unsigned long psp)
        rval = (csp - distance);
        if (copy_in_user((void __user *) rval, (void __user *) psp, distance))
                rval = 0;
-       else if (test_thread_flag(TIF_32BIT)) {
+       else if (!stack_64bit) {
                if (put_user(((u32)csp),
                             &(((struct reg_window32 __user *)rval)->ins[6])))
                        rval = 0;
@@ -507,18 +510,18 @@ void synchronize_user_stack(void)
 
        flush_user_windows();
        if ((window = get_thread_wsaved()) != 0) {
-               int winsize = sizeof(struct reg_window);
-               int bias = 0;
-
-               if (test_thread_flag(TIF_32BIT))
-                       winsize = sizeof(struct reg_window32);
-               else
-                       bias = STACK_BIAS;
-
                window -= 1;
                do {
-                       unsigned long sp = (t->rwbuf_stkptrs[window] + bias);
                        struct reg_window *rwin = &t->reg_window[window];
+                       int winsize = sizeof(struct reg_window);
+                       unsigned long sp;
+
+                       sp = t->rwbuf_stkptrs[window];
+
+                       if (test_thread_64bit_stack(sp))
+                               sp += STACK_BIAS;
+                       else
+                               winsize = sizeof(struct reg_window32);
 
                        if (!copy_to_user((char __user *)sp, rwin, winsize)) {
                                shift_window_buffer(window, get_thread_wsaved() - 1, t);
@@ -544,13 +547,6 @@ void fault_in_user_windows(void)
 {
        struct thread_info *t = current_thread_info();
        unsigned long window;
-       int winsize = sizeof(struct reg_window);
-       int bias = 0;
-
-       if (test_thread_flag(TIF_32BIT))
-               winsize = sizeof(struct reg_window32);
-       else
-               bias = STACK_BIAS;
 
        flush_user_windows();
        window = get_thread_wsaved();
@@ -558,8 +554,16 @@ void fault_in_user_windows(void)
        if (likely(window != 0)) {
                window -= 1;
                do {
-                       unsigned long sp = (t->rwbuf_stkptrs[window] + bias);
                        struct reg_window *rwin = &t->reg_window[window];
+                       int winsize = sizeof(struct reg_window);
+                       unsigned long sp;
+
+                       sp = t->rwbuf_stkptrs[window];
+
+                       if (test_thread_64bit_stack(sp))
+                               sp += STACK_BIAS;
+                       else
+                               winsize = sizeof(struct reg_window32);
 
                        if (unlikely(sp & 0x7UL))
                                stack_unaligned(sp);
index 484dabac7045aa2177df26f625ffabf9f6f523c7..7ff45e4ba6815080a29e02a64ad79bfdf9c1ed12 100644 (file)
@@ -151,7 +151,7 @@ static int regwindow64_get(struct task_struct *target,
 {
        unsigned long rw_addr = regs->u_regs[UREG_I6];
 
-       if (test_tsk_thread_flag(current, TIF_32BIT)) {
+       if (!test_thread_64bit_stack(rw_addr)) {
                struct reg_window32 win32;
                int i;
 
@@ -176,7 +176,7 @@ static int regwindow64_set(struct task_struct *target,
 {
        unsigned long rw_addr = regs->u_regs[UREG_I6];
 
-       if (test_tsk_thread_flag(current, TIF_32BIT)) {
+       if (!test_thread_64bit_stack(rw_addr)) {
                struct reg_window32 win32;
                int i;
 
index 11c6c9603e71f03995a3c17fcdf2f28957d7fa43..878ef3d5fec522d6b23d0640df962f33c2b958df 100644 (file)
@@ -751,3 +751,8 @@ int kernel_execve(const char *filename,
                      : "cc");
        return __res;
 }
+
+asmlinkage long sys_kern_features(void)
+{
+       return KERN_FEATURE_MIXED_MODE_STACK;
+}
index 3a58e0d66f51b0144ef5f9ca970bfbbbb9d01ed6..45ce6be088e44bdc2d479edf1130c01e79685921 100644 (file)
@@ -86,6 +86,7 @@ sys_call_table32:
        .word compat_sys_pwritev, compat_sys_rt_tgsigqueueinfo, sys_perf_event_open, compat_sys_recvmmsg, sys_fanotify_init
 /*330*/        .word sys32_fanotify_mark, sys_prlimit64, sys_name_to_handle_at, compat_sys_open_by_handle_at, compat_sys_clock_adjtime
        .word sys_syncfs, compat_sys_sendmmsg, sys_setns, compat_sys_process_vm_readv, compat_sys_process_vm_writev
+/*340*/        .word sys_kern_features
 
 #endif /* CONFIG_COMPAT */
 
@@ -163,3 +164,4 @@ sys_call_table:
        .word sys_pwritev, sys_rt_tgsigqueueinfo, sys_perf_event_open, sys_recvmmsg, sys_fanotify_init
 /*330*/        .word sys_fanotify_mark, sys_prlimit64, sys_name_to_handle_at, sys_open_by_handle_at, sys_clock_adjtime
        .word sys_syncfs, sys_sendmmsg, sys_setns, sys_process_vm_readv, sys_process_vm_writev
+/*340*/        .word sys_kern_features
index f81d038f7340ce6b80cb65e0e27b2e7f2cb9edd2..8201c25e76697ad5f5a96de1b6921a3fb34372ac 100644 (file)
@@ -113,21 +113,24 @@ static inline long sign_extend_imm13(long imm)
 
 static unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
 {
-       unsigned long value;
+       unsigned long value, fp;
        
        if (reg < 16)
                return (!reg ? 0 : regs->u_regs[reg]);
+
+       fp = regs->u_regs[UREG_FP];
+
        if (regs->tstate & TSTATE_PRIV) {
                struct reg_window *win;
-               win = (struct reg_window *)(regs->u_regs[UREG_FP] + STACK_BIAS);
+               win = (struct reg_window *)(fp + STACK_BIAS);
                value = win->locals[reg - 16];
-       } else if (test_thread_flag(TIF_32BIT)) {
+       } else if (!test_thread_64bit_stack(fp)) {
                struct reg_window32 __user *win32;
-               win32 = (struct reg_window32 __user *)((unsigned long)((u32)regs->u_regs[UREG_FP]));
+               win32 = (struct reg_window32 __user *)((unsigned long)((u32)fp));
                get_user(value, &win32->locals[reg - 16]);
        } else {
                struct reg_window __user *win;
-               win = (struct reg_window __user *)(regs->u_regs[UREG_FP] + STACK_BIAS);
+               win = (struct reg_window __user *)(fp + STACK_BIAS);
                get_user(value, &win->locals[reg - 16]);
        }
        return value;
@@ -135,19 +138,24 @@ static unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
 
 static unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
 {
+       unsigned long fp;
+
        if (reg < 16)
                return &regs->u_regs[reg];
+
+       fp = regs->u_regs[UREG_FP];
+
        if (regs->tstate & TSTATE_PRIV) {
                struct reg_window *win;
-               win = (struct reg_window *)(regs->u_regs[UREG_FP] + STACK_BIAS);
+               win = (struct reg_window *)(fp + STACK_BIAS);
                return &win->locals[reg - 16];
-       } else if (test_thread_flag(TIF_32BIT)) {
+       } else if (!test_thread_64bit_stack(fp)) {
                struct reg_window32 *win32;
-               win32 = (struct reg_window32 *)((unsigned long)((u32)regs->u_regs[UREG_FP]));
+               win32 = (struct reg_window32 *)((unsigned long)((u32)fp));
                return (unsigned long *)&win32->locals[reg - 16];
        } else {
                struct reg_window *win;
-               win = (struct reg_window *)(regs->u_regs[UREG_FP] + STACK_BIAS);
+               win = (struct reg_window *)(fp + STACK_BIAS);
                return &win->locals[reg - 16];
        }
 }
@@ -392,13 +400,15 @@ int handle_popc(u32 insn, struct pt_regs *regs)
                if (rd)
                        regs->u_regs[rd] = ret;
        } else {
-               if (test_thread_flag(TIF_32BIT)) {
+               unsigned long fp = regs->u_regs[UREG_FP];
+
+               if (!test_thread_64bit_stack(fp)) {
                        struct reg_window32 __user *win32;
-                       win32 = (struct reg_window32 __user *)((unsigned long)((u32)regs->u_regs[UREG_FP]));
+                       win32 = (struct reg_window32 __user *)((unsigned long)((u32)fp));
                        put_user(ret, &win32->locals[rd - 16]);
                } else {
                        struct reg_window __user *win;
-                       win = (struct reg_window __user *)(regs->u_regs[UREG_FP] + STACK_BIAS);
+                       win = (struct reg_window __user *)(fp + STACK_BIAS);
                        put_user(ret, &win->locals[rd - 16]);
                }
        }
@@ -554,7 +564,7 @@ void handle_ld_nf(u32 insn, struct pt_regs *regs)
                reg[0] = 0;
                if ((insn & 0x780000) == 0x180000)
                        reg[1] = 0;
-       } else if (test_thread_flag(TIF_32BIT)) {
+       } else if (!test_thread_64bit_stack(regs->u_regs[UREG_FP])) {
                put_user(0, (int __user *) reg);
                if ((insn & 0x780000) == 0x180000)
                        put_user(0, ((int __user *) reg) + 1);
index 08e074b7eb6a025e985700e0bf2443ef30fcb1d2..c096c624ac4d44ad6bd723b4bce88510dcdf70f5 100644 (file)
@@ -149,21 +149,24 @@ static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
 
 static unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
 {
-       unsigned long value;
+       unsigned long value, fp;
        
        if (reg < 16)
                return (!reg ? 0 : regs->u_regs[reg]);
+
+       fp = regs->u_regs[UREG_FP];
+
        if (regs->tstate & TSTATE_PRIV) {
                struct reg_window *win;
-               win = (struct reg_window *)(regs->u_regs[UREG_FP] + STACK_BIAS);
+               win = (struct reg_window *)(fp + STACK_BIAS);
                value = win->locals[reg - 16];
-       } else if (test_thread_flag(TIF_32BIT)) {
+       } else if (!test_thread_64bit_stack(fp)) {
                struct reg_window32 __user *win32;
-               win32 = (struct reg_window32 __user *)((unsigned long)((u32)regs->u_regs[UREG_FP]));
+               win32 = (struct reg_window32 __user *)((unsigned long)((u32)fp));
                get_user(value, &win32->locals[reg - 16]);
        } else {
                struct reg_window __user *win;
-               win = (struct reg_window __user *)(regs->u_regs[UREG_FP] + STACK_BIAS);
+               win = (struct reg_window __user *)(fp + STACK_BIAS);
                get_user(value, &win->locals[reg - 16]);
        }
        return value;
@@ -172,16 +175,18 @@ static unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
 static inline unsigned long __user *__fetch_reg_addr_user(unsigned int reg,
                                                          struct pt_regs *regs)
 {
+       unsigned long fp = regs->u_regs[UREG_FP];
+
        BUG_ON(reg < 16);
        BUG_ON(regs->tstate & TSTATE_PRIV);
 
-       if (test_thread_flag(TIF_32BIT)) {
+       if (!test_thread_64bit_stack(fp)) {
                struct reg_window32 __user *win32;
-               win32 = (struct reg_window32 __user *)((unsigned long)((u32)regs->u_regs[UREG_FP]));
+               win32 = (struct reg_window32 __user *)((unsigned long)((u32)fp));
                return (unsigned long __user *)&win32->locals[reg - 16];
        } else {
                struct reg_window __user *win;
-               win = (struct reg_window __user *)(regs->u_regs[UREG_FP] + STACK_BIAS);
+               win = (struct reg_window __user *)(fp + STACK_BIAS);
                return &win->locals[reg - 16];
        }
 }
@@ -204,7 +209,7 @@ static void store_reg(struct pt_regs *regs, unsigned long val, unsigned long rd)
        } else {
                unsigned long __user *rd_user = __fetch_reg_addr_user(rd, regs);
 
-               if (test_thread_flag(TIF_32BIT))
+               if (!test_thread_64bit_stack(regs->u_regs[UREG_FP]))
                        __put_user((u32)val, (u32 __user *)rd_user);
                else
                        __put_user(val, rd_user);
index a6b0863c27df48e12bfa656a83783fee6ecfa05c..1e67ce95836972d439b50c88aa77d8395a543652 100644 (file)
@@ -43,6 +43,8 @@ spill_fixup_mna:
 spill_fixup_dax:
        TRAP_LOAD_THREAD_REG(%g6, %g1)
        ldx     [%g6 + TI_FLAGS], %g1
+       andcc   %sp, 0x1, %g0
+       movne   %icc, 0, %g1
        andcc   %g1, _TIF_32BIT, %g0
        ldub    [%g6 + TI_WSAVED], %g1
        sll     %g1, 3, %g3
index 1704068da92806d5868d0374bea669f31f21b113..034aadbff036fd617c8cae7afbcac20eee0ecaf8 100644 (file)
@@ -320,7 +320,7 @@ int do_mathemu(struct pt_regs *regs, struct fpustate *f, bool illegal_insn_trap)
                                        XR = 0;
                                else if (freg < 16)
                                        XR = regs->u_regs[freg];
-                               else if (test_thread_flag(TIF_32BIT)) {
+                               else if (!test_thread_64bit_stack(regs->u_regs[UREG_FP])) {
                                        struct reg_window32 __user *win32;
                                        flushw_user ();
                                        win32 = (struct reg_window32 __user *)((unsigned long)((u32)regs->u_regs[UREG_FP]));