parisc: Add ALTERNATIVE_CODE() and ALT_COND_RUN_ON_QEMU

The macro ALTERNATIVE_CODE() allows assembly code to patch in a series
of new assembler statements given at a specific start address.
The ALT_COND_RUN_ON_QEMU condition is true if the kernel is started in a
qemu emulation.

Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/include/asm/alternative.h b/arch/parisc/include/asm/alternative.h
index 793d8ba..0ec54f4 100644 (file)
--- a/arch/parisc/include/asm/alternative.h
+++ b/arch/parisc/include/asm/alternative.h
@@ -8,6 +8,7 @@
 #define ALT_COND_NO_ICACHE     0x04    /* if system has no i-cache  */
 #define ALT_COND_NO_SPLIT_TLB  0x08    /* if split_tlb == 0  */
 #define ALT_COND_NO_IOC_FDC    0x10    /* if I/O cache does not need flushes */
+#define ALT_COND_RUN_ON_QEMU   0x20    /* if running on QEMU */
 
 #define INSN_PxTLB     0x02            /* modify pdtlb, pitlb */
 #define INSN_NOP       0x08000240      /* nop */
@@ -21,7 +22,7 @@
 
 struct alt_instr {
        s32 orig_offset;        /* offset to original instructions */
-       u32 len;                /* end of original instructions */
+       s32 len;                /* end of original instructions */
        u32 cond;               /* see ALT_COND_XXX */
        u32 replacement;        /* replacement instruction or code */
 };
@@ -40,12 +41,20 @@ void apply_alternatives(struct alt_instr *start, struct alt_instr *end,
 
 #else
 
+/* to replace one single instructions by a new instruction */
 #define ALTERNATIVE(from, to, cond, replacement)\
        .section .altinstructions, "aw" !       \
        .word (from - .), (to - from)/4 !       \
        .word cond, replacement         !       \
        .previous
 
+/* to replace multiple instructions by new code */
+#define ALTERNATIVE_CODE(from, num_instructions, cond, new_instr_ptr)\
+       .section .altinstructions, "aw" !       \
+       .word (from - .), -num_instructions !   \
+       .word cond, (new_instr_ptr - .) !       \
+       .previous
+
 #endif  /*  __ASSEMBLY__  */
 
 #endif /* __ASM_PARISC_ALTERNATIVE_H */

diff --git a/arch/parisc/kernel/alternative.c b/arch/parisc/kernel/alternative.c
index ca1f5ca..3c66d5c 100644 (file)
--- a/arch/parisc/kernel/alternative.c
+++ b/arch/parisc/kernel/alternative.c
@@ -28,7 +28,8 @@ void __init_or_module apply_alternatives(struct alt_instr *start,
 
        for (entry = start; entry < end; entry++, index++) {
 
-               u32 *from, len, cond, replacement;
+               u32 *from, cond, replacement;
+               s32 len;
 
                from = (u32 *)((ulong)&entry->orig_offset + entry->orig_offset);
                len = entry->len;
@@ -49,6 +50,8 @@ void __init_or_module apply_alternatives(struct alt_instr *start,
                        continue;
                if ((cond & ALT_COND_NO_ICACHE) && (cache_info.ic_size != 0))
                        continue;
+               if ((cond & ALT_COND_RUN_ON_QEMU) && !running_on_qemu)
+                       continue;
 
                /*
                 * If the PDC_MODEL capabilities has Non-coherent IO-PDIR bit
@@ -74,11 +77,19 @@ void __init_or_module apply_alternatives(struct alt_instr *start,
                if (replacement == INSN_NOP && len > 1)
                        replacement = 0xe8000002 + (len-2)*8; /* "b,n .+8" */
 
-               pr_debug("Do    %d: Cond 0x%x, Replace %02d instructions @ 0x%px with 0x%08x\n",
-                       index, cond, len, from, replacement);
-
-               /* Replace instruction */
-               *from = replacement;
+               pr_debug("ALTERNATIVE %3d: Cond %2x, Replace %2d instructions to 0x%08x @ 0x%px (%pS)\n",
+                       index, cond, len, replacement, from, from);
+
+               if (len < 0) {
+                       /* Replace multiple instruction by new code */
+                       u32 *source;
+                       len = -len;
+                       source = (u32 *)((ulong)&entry->replacement + entry->replacement);
+                       memcpy(from, source, 4 * len);
+               } else {
+                       /* Replace by one instruction */
+                       *from = replacement;
+               }
                applied++;
        }