Cleanup: kallsyms wrapper refactoring

[lttng-modules.git] / src / wrapper / kallsyms.c

diff --git a/src/wrapper/kallsyms.c b/src/wrapper/kallsyms.c
index 6af77f538950d7b3718bd33fffb749053ae03333..2535c2a527faed90f20909ce809334adaae28169 100644 (file)
--- a/src/wrapper/kallsyms.c
+++ b/src/wrapper/kallsyms.c
@@ -14,7 +14,7 @@
 #include <linux/module.h>
 #include <wrapper/kallsyms.h>
 
-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0))
+#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,7,0))
 
 #ifndef CONFIG_KPROBES
 # error "LTTng-modules requires CONFIG_KPROBES on kernels >= 5.7.0"
@@ -29,6 +29,80 @@ int dummy_kprobe_handler(struct kprobe *p, struct pt_regs *regs)
        return 0;
 }
 
+#ifdef LTTNG_CONFIG_PPC64_ELF_ABI_V2
+static
+void kallsyms_pre_arch_adjust(struct kprobe *probe)
+{
+       /*
+        * With powerpc64 ABIv2, we need the global entry point of
+        * kallsyms_lookup_name to call it later, while kprobe_register would
+        * automatically adjust the global entry point to the local entry point,
+        * when a kprobe was registered at a function entry. So we add 4 bytes
+        * which is the length of one instruction to kallsyms_lookup_name to
+        * avoid the adjustment.
+        */
+       probe->offset = 4;
+}
+#else
+static
+void kallsyms_pre_arch_adjust(struct kprobe *probe)
+{
+}
+#endif
+
+#ifdef LTTNG_CONFIG_PPC64_ELF_ABI_V2
+static
+unsigned long kallsyms_get_arch_call_addr(const struct kprobe *probe)
+{
+       /* Substract 4 bytes to get what we originally want */
+       return (unsigned long)(((char *)probe->addr) - 4);
+}
+
+#elif defined(LTTNG_CONFIG_PPC64_ELF_ABI_V1)
+# if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,18,0))
+# include <asm/elf.h>
+# define LTTNG_FUNC_DESC_TYPE struct func_desc
+# define LTTNG_FUNC_DESC_ADDR_NAME addr
+# else
+# include <asm/types.h>
+# define LTTNG_FUNC_DESC_TYPE func_descr_t
+# define LTTNG_FUNC_DESC_ADDR_NAME entry
+
+static
+LTTNG_FUNC_DESC_TYPE kallsyms_lookup_name_func_desc;
+# endif
+
+static
+unsigned long kallsyms_get_arch_call_addr(const struct kprobe *probe)
+{
+       /*
+        * Build a function descriptor from the address of
+        * 'kallsyms_lookup_name' returned by kprobe and the toc of
+        * 'sprint_symbol' which is in the same compile unit and exported. I
+        * hate this on so many levels but it works.
+        */
+       kallsyms_lookup_name_func_desc.LTTNG_FUNC_DESC_ADDR_NAME = (unsigned long) probe.addr;
+       kallsyms_lookup_name_func_desc.toc = ((LTTNG_FUNC_DESC_TYPE *) &sprint_symbol)->toc;
+       return (unsigned long) &kallsyms_lookup_name_func_desc;
+}
+#elif defined(CONFIG_ARM) && defined(CONFIG_THUMB2_KERNEL)
+static
+unsigned long kallsyms_get_arch_call_addr(const struct kprobe *probe)
+{
+       unsigned long addr = (unsigned long)probe->addr;
+
+       if (addr)
+               addr |= 1; /* set bit 0 in address for thumb mode */
+       return addr;
+}
+#else
+static
+unsigned long kallsyms_get_arch_call_addr(const struct kprobe *probe)
+{
+       return (unsigned long)probe->addr;
+}
+#endif
+
 static
 unsigned long do_get_kallsyms(void)
 {
@@ -39,16 +113,11 @@ unsigned long do_get_kallsyms(void)
        memset(&probe, 0, sizeof(probe));
        probe.pre_handler = dummy_kprobe_handler;
        probe.symbol_name = "kallsyms_lookup_name";
+       kallsyms_pre_arch_adjust(&probe);
        ret = register_kprobe(&probe);
        if (ret)
                return 0;
-       addr = (unsigned long)probe.addr;
-#ifdef CONFIG_ARM
-#ifdef CONFIG_THUMB2_KERNEL
-       if (addr)
-               addr |= 1; /* set bit 0 in address for thumb mode */
-#endif
-#endif
+       addr = kallsyms_get_arch_call_addr(&probe);
        unregister_kprobe(&probe);
        return addr;
 }
@@ -61,10 +130,14 @@ unsigned long wrapper_kallsyms_lookup_name(const char *name)
        if (kallsyms_lookup_name_sym)
                return kallsyms_lookup_name_sym(name);
        else {
-               printk_once(KERN_WARNING "LTTng requires kallsyms_lookup_name\n");
+               printk_once(KERN_WARNING "LTTng: requires kallsyms_lookup_name\n");
                return 0;
        }
 }
 EXPORT_SYMBOL_GPL(wrapper_kallsyms_lookup_name);
 
 #endif
+
+#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,4,0) && defined(CONFIG_ANDROID))
+MODULE_IMPORT_NS(VFS_internal_I_am_really_a_filesystem_and_am_NOT_a_driver);
+#endif