x86/ibt,paravirt: Use text_gen_insn() for paravirt_patch()

Less duplication is more better.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.697253958@infradead.org

diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index 1c4cfb1..c6015b4 100644 (file)
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -96,32 +96,40 @@ union text_poke_insn {
 };
 
 static __always_inline
-void *text_gen_insn(u8 opcode, const void *addr, const void *dest)
+void __text_gen_insn(void *buf, u8 opcode, const void *addr, const void *dest, int size)
 {
-       static union text_poke_insn insn; /* per instance */
-       int size = text_opcode_size(opcode);
+       union text_poke_insn *insn = buf;
+
+       BUG_ON(size < text_opcode_size(opcode));
 
        /*
         * Hide the addresses to avoid the compiler folding in constants when
         * referencing code, these can mess up annotations like
         * ANNOTATE_NOENDBR.
         */
+       OPTIMIZER_HIDE_VAR(insn);
        OPTIMIZER_HIDE_VAR(addr);
        OPTIMIZER_HIDE_VAR(dest);
 
-       insn.opcode = opcode;
+       insn->opcode = opcode;
 
        if (size > 1) {
-               insn.disp = (long)dest - (long)(addr + size);
+               insn->disp = (long)dest - (long)(addr + size);
                if (size == 2) {
                        /*
                         * Ensure that for JMP8 the displacement
                         * actually fits the signed byte.
                         */
-                       BUG_ON((insn.disp >> 31) != (insn.disp >> 7));
+                       BUG_ON((insn->disp >> 31) != (insn->disp >> 7));
                }
        }
+}
 
+static __always_inline
+void *text_gen_insn(u8 opcode, const void *addr, const void *dest)
+{
+       static union text_poke_insn insn; /* per instance */
+       __text_gen_insn(&insn, opcode, addr, dest, text_opcode_size(opcode));
        return &insn.text;
 }
 

diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 4420499..06af2cf 100644 (file)
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -69,29 +69,12 @@ noinstr void paravirt_BUG(void)
        BUG();
 }
 
-struct branch {
-       unsigned char opcode;
-       u32 delta;
-} __attribute__((packed));
-
 static unsigned paravirt_patch_call(void *insn_buff, const void *target,
                                    unsigned long addr, unsigned len)
 {
-       const int call_len = 5;
-       struct branch *b = insn_buff;
-       unsigned long delta = (unsigned long)target - (addr+call_len);
-
-       if (len < call_len) {
-               pr_warn("paravirt: Failed to patch indirect CALL at %ps\n", (void *)addr);
-               /* Kernel might not be viable if patching fails, bail out: */
-               BUG_ON(1);
-       }
-
-       b->opcode = 0xe8; /* call */
-       b->delta = delta;
-       BUILD_BUG_ON(sizeof(*b) != call_len);
-
-       return call_len;
+       __text_gen_insn(insn_buff, CALL_INSN_OPCODE,
+                       (void *)addr, target, CALL_INSN_SIZE);
+       return CALL_INSN_SIZE;
 }
 
 #ifdef CONFIG_PARAVIRT_XXL