X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=src%2Fwrapper%2Fkallsyms.c;h=97897c425469ea5411a0feded86a0ad03f9b8942;hb=a1f1ecf44b7798d27c762f37afe5cea518fec534;hp=6af77f538950d7b3718bd33fffb749053ae03333;hpb=cfa6cc1d0f01c2cfcc1a679abf3a6572d411c309;p=lttng-modules.git

diff --git a/src/wrapper/kallsyms.c b/src/wrapper/kallsyms.c
index 6af77f53..97897c42 100644
--- a/src/wrapper/kallsyms.c
+++ b/src/wrapper/kallsyms.c
@@ -14,12 +14,31 @@
 #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"
 #endif
 
+#ifdef 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
+#endif
+
+static
+LTTNG_FUNC_DESC_TYPE kallsyms_lookup_name_func_desc;
+#endif
+
 static
 unsigned long (*kallsyms_lookup_name_sym)(const char *name);
 
@@ -39,10 +58,36 @@ unsigned long do_get_kallsyms(void)
 	memset(&probe, 0, sizeof(probe));
 	probe.pre_handler = dummy_kprobe_handler;
 	probe.symbol_name = "kallsyms_lookup_name";
+#ifdef LTTNG_CONFIG_PPC64_ELF_ABI_V2
+	/*
+	 * 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;
+#endif
 	ret = register_kprobe(&probe);
 	if (ret)
 		return 0;
+#ifdef LTTNG_CONFIG_PPC64_ELF_ABI_V2
+	/* Substract 4 bytes to get what we originally want */
+	addr = (unsigned long)(((char *)probe.addr) - 4);
+#elif defined(LTTNG_CONFIG_PPC64_ELF_ABI_V1)
+	/*
+	 * 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;
+	addr = (unsigned long) &kallsyms_lookup_name_func_desc;
+#else
 	addr = (unsigned long)probe.addr;
+#endif
 #ifdef CONFIG_ARM
 #ifdef CONFIG_THUMB2_KERNEL
 	if (addr)
@@ -61,7 +106,7 @@ 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;
 	}
 }