X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-ust-elf.c;h=5f27920e48fa041f1d971677b56c643993064de9;hb=8620f4268b34a903a9c23137dd2400fc69096b7c;hp=e90626906b6ea72c24d19bbcd4a3b7cee92e0821;hpb=aaf93c608bb7591f0a5411c221a3ad3fbd8efdfd;p=lttng-ust.git

diff --git a/liblttng-ust/lttng-ust-elf.c b/liblttng-ust/lttng-ust-elf.c
index e9062690..5f27920e 100644
--- a/liblttng-ust/lttng-ust-elf.c
+++ b/liblttng-ust/lttng-ust-elf.c
@@ -316,6 +316,18 @@ error:
 	return NULL;
 }
 
+/*
+ * Test whether the ELF file is position independent code (PIC)
+ */
+uint8_t lttng_ust_elf_is_pic(struct lttng_ust_elf *elf)
+{
+	/*
+	 * PIC has and e_type value of ET_DYN, see ELF specification
+	 * version 1.1 p. 1-3.
+	 */
+	return elf->ehdr->e_type == ET_DYN;
+}
+
 /*
  * Destroy the given lttng_ust_elf instance.
  */
@@ -342,7 +354,7 @@ void lttng_ust_elf_destroy(struct lttng_ust_elf *elf)
 int lttng_ust_elf_get_memsz(struct lttng_ust_elf *elf, uint64_t *memsz)
 {
 	uint16_t i;
-	uint64_t _memsz = 0;
+	uint64_t low_addr = UINT64_MAX, high_addr = 0;
 
 	if (!elf || !memsz) {
 		goto error;
@@ -350,7 +362,6 @@ int lttng_ust_elf_get_memsz(struct lttng_ust_elf *elf, uint64_t *memsz)
 
 	for (i = 0; i < elf->ehdr->e_phnum; ++i) {
 		struct lttng_ust_elf_phdr *phdr;
-		uint64_t align;
 
 		phdr = lttng_ust_elf_get_phdr(elf, i);
 		if (!phdr) {
@@ -365,27 +376,19 @@ int lttng_ust_elf_get_memsz(struct lttng_ust_elf *elf, uint64_t *memsz)
 			goto next_loop;
 		}
 
-		/*
-		 * A p_align of 0 means no alignment, i.e. aligned to
-		 * 1 byte.
-		 */
-		align = phdr->p_align == 0 ? 1 : phdr->p_align;
-		/* Align the start of the segment. */
-		_memsz += offset_align(_memsz, align);
-		_memsz += phdr->p_memsz;
-		/*
-		 * Add padding at the end of the segment, so it ends
-		 * on a multiple of the align value (which usually
-		 * means a page boundary). This makes the computation
-		 * valid even in cases where p_align would change from
-		 * one segment to the next.
-		 */
-		_memsz += offset_align(_memsz, align);
+		low_addr = min_t(uint64_t, low_addr, phdr->p_vaddr);
+		high_addr = max_t(uint64_t, high_addr,
+				phdr->p_vaddr + phdr->p_memsz);
 	next_loop:
 		free(phdr);
 	}
 
-	*memsz = _memsz;
+	if (high_addr < low_addr) {
+		/* No PT_LOAD segments or corrupted data. */
+		goto error;
+	}
+
+	*memsz = high_addr - low_addr;
 	return 0;
 error:
 	return -1;