powerpc/64: vmlinux support building with PCREL addresing

[linux-block.git] / arch / powerpc / kernel / trace / ftrace.c

diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 7b85c3b460a3c048ec31cce44e9b21066b96c5a8..a47f303734233b62038637b5527eeea5d3097cae 100644 (file)
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -194,6 +194,8 @@ __ftrace_make_nop(struct module *mod,
         * get corrupted.
         *
         * Use a b +8 to jump over the load.
+        * XXX: could make PCREL depend on MPROFILE_KERNEL
+        * XXX: check PCREL && MPROFILE_KERNEL calling sequence
         */
        if (IS_ENABLED(CONFIG_MPROFILE_KERNEL) || IS_ENABLED(CONFIG_PPC32))
                pop = ppc_inst(PPC_RAW_NOP());
@@ -725,6 +727,15 @@ int __init ftrace_dyn_arch_init(void)
 {
        int i;
        unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
+#ifdef CONFIG_PPC_KERNEL_PCREL
+       u32 stub_insns[] = {
+               /* pla r12,addr */
+               PPC_PREFIX_MLS | __PPC_PRFX_R(1),
+               PPC_INST_PADDI | ___PPC_RT(_R12),
+               PPC_RAW_MTCTR(_R12),
+               PPC_RAW_BCTR()
+       };
+#else
        u32 stub_insns[] = {
                PPC_RAW_LD(_R12, _R13, PACATOC),
                PPC_RAW_ADDIS(_R12, _R12, 0),
@@ -732,6 +743,8 @@ int __init ftrace_dyn_arch_init(void)
                PPC_RAW_MTCTR(_R12),
                PPC_RAW_BCTR()
        };
+#endif
+
        unsigned long addr;
        long reladdr;
 
@@ -740,19 +753,36 @@ int __init ftrace_dyn_arch_init(void)
        else
                addr = ppc_global_function_entry((void *)ftrace_caller);
 
-       reladdr = addr - kernel_toc_addr();
+       if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
+               for (i = 0; i < 2; i++) {
+                       reladdr = addr - (unsigned long)tramp[i];
 
-       if (reladdr >= SZ_2G || reladdr < -(long)SZ_2G) {
-               pr_err("Address of %ps out of range of kernel_toc.\n",
+                       if (reladdr >= (long)SZ_8G || reladdr < -(long)SZ_8G) {
+                               pr_err("Address of %ps out of range of pcrel address.\n",
+                                       (void *)addr);
+                               return -1;
+                       }
+
+                       memcpy(tramp[i], stub_insns, sizeof(stub_insns));
+                       tramp[i][0] |= IMM_H18(reladdr);
+                       tramp[i][1] |= IMM_L(reladdr);
+                       add_ftrace_tramp((unsigned long)tramp[i]);
+               }
+       } else {
+               reladdr = addr - kernel_toc_addr();
+
+               if (reladdr >= (long)SZ_2G || reladdr < -(long)SZ_2G) {
+                       pr_err("Address of %ps out of range of kernel_toc.\n",
                                (void *)addr);
-               return -1;
-       }
+                       return -1;
+               }
 
-       for (i = 0; i < 2; i++) {
-               memcpy(tramp[i], stub_insns, sizeof(stub_insns));
-               tramp[i][1] |= PPC_HA(reladdr);
-               tramp[i][2] |= PPC_LO(reladdr);
-               add_ftrace_tramp((unsigned long)tramp[i]);
+               for (i = 0; i < 2; i++) {
+                       memcpy(tramp[i], stub_insns, sizeof(stub_insns));
+                       tramp[i][1] |= PPC_HA(reladdr);
+                       tramp[i][2] |= PPC_LO(reladdr);
+                       add_ftrace_tramp((unsigned long)tramp[i]);
+               }
        }
 
        return 0;