xtensa: save and restore scompare1 SR on kernel entry

Although scompare1 may be saved/restored by xchal_ncp_{load,store}
macros, explicit save/restore of registers manipulated by the kernel
itself is considered more correct.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

diff --git a/arch/xtensa/include/asm/ptrace.h b/arch/xtensa/include/asm/ptrace.h
index da21c17..9fe249c 100644 (file)
--- a/arch/xtensa/include/asm/ptrace.h
+++ b/arch/xtensa/include/asm/ptrace.h
@@ -37,7 +37,7 @@ struct pt_regs {
        unsigned long windowstart;      /*  52 */
        unsigned long syscall;          /*  56 */
        unsigned long icountlevel;      /*  60 */
-       int reserved[1];                /*  64 */
+       unsigned long scompare1;        /*  64 */
 
        /* Additional configurable registers that are used by the compiler. */
        xtregs_opt_t xtregs_opt;

diff --git a/arch/xtensa/kernel/asm-offsets.c b/arch/xtensa/kernel/asm-offsets.c
index 7dc3f91..845475a 100644 (file)
--- a/arch/xtensa/kernel/asm-offsets.c
+++ b/arch/xtensa/kernel/asm-offsets.c
@@ -41,6 +41,7 @@ int main(void)
        DEFINE(PT_SAR, offsetof (struct pt_regs, sar));
        DEFINE(PT_ICOUNTLEVEL, offsetof (struct pt_regs, icountlevel));
        DEFINE(PT_SYSCALL, offsetof (struct pt_regs, syscall));
+       DEFINE(PT_SCOMPARE1, offsetof(struct pt_regs, scompare1));
        DEFINE(PT_AREG, offsetof (struct pt_regs, areg[0]));
        DEFINE(PT_AREG0, offsetof (struct pt_regs, areg[0]));
        DEFINE(PT_AREG1, offsetof (struct pt_regs, areg[1]));

diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index 41ad9cf..4c2f270 100644 (file)
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -372,6 +372,13 @@ common_exception:
        s32i    a2, a1, PT_LBEG
        s32i    a3, a1, PT_LEND
 
+       /* Save SCOMPARE1 */
+
+#if XCHAL_HAVE_S32C1I
+       rsr     a2, scompare1
+       s32i    a2, a1, PT_SCOMPARE1
+#endif
+
        /* Save optional registers. */
 
        save_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT
@@ -433,6 +440,12 @@ common_exception_return:
 
        load_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT
 
+       /* Restore SCOMPARE1 */
+
+#if XCHAL_HAVE_S32C1I
+       l32i    a2, a1, PT_SCOMPARE1
+       wsr     a2, scompare1
+#endif
        wsr     a3, ps          /* disable interrupts */
 
        _bbci.l a3, PS_UM_BIT, kernel_exception_exit