X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=wrapper%2Fkallsyms.c;h=e50cfe280eb025327d3df53e403583cc7724c921;hb=edee4485348d15198bc76a4fb4ae2d27e9872364;hp=d892a2f4860a3b783296b3a0ad8f87011114fea9;hpb=2d0428212cbfa3f8428feee160b095f48c2ac974;p=lttng-modules.git

diff --git a/wrapper/kallsyms.c b/wrapper/kallsyms.c
index d892a2f4..e50cfe28 100644
--- a/wrapper/kallsyms.c
+++ b/wrapper/kallsyms.c
@@ -20,6 +20,25 @@
 # 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)