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authorMark Johnston <markj@FreeBSD.org>2019-12-29 21:46:50 +0000
committerMark Johnston <markj@FreeBSD.org>2019-12-29 21:46:50 +0000
commita2ea78495a13f81658872540632eb8d4baf0087f (patch)
tree147b94e659ff819fa6c0ad03a24096d11c6c9ee3 /cddl
parent78347412c0e7af3d263b16d71ebc79795e8eacd4 (diff)
downloadsrc-a2ea78495a13f81658872540632eb8d4baf0087f.tar.gz
src-a2ea78495a13f81658872540632eb8d4baf0087f.zip
Add libdtrace support for arm64 USDT probes.
arm64 is still lacking a fasttrap implementation, which is required to actually enable userland probes, but this at least allows USDT probes to be linked into userland applications. Submitted by: Klaus K├╝chemann <maciphone2@googlemail.com> (original) MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D22360
Notes
Notes: svn path=/head/; revision=356187
Diffstat (limited to 'cddl')
-rw-r--r--cddl/contrib/opensolaris/lib/libdtrace/common/dt_link.c78
1 files changed, 70 insertions, 8 deletions
diff --git a/cddl/contrib/opensolaris/lib/libdtrace/common/dt_link.c b/cddl/contrib/opensolaris/lib/libdtrace/common/dt_link.c
index 8dad7428722e..1346c3df1866 100644
--- a/cddl/contrib/opensolaris/lib/libdtrace/common/dt_link.c
+++ b/cddl/contrib/opensolaris/lib/libdtrace/common/dt_link.c
@@ -229,9 +229,10 @@ prepare_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf32_t *dep)
for (j = 0; j < nrel; j++) {
#if defined(__aarch64__)
-/* XXX */
- printf("%s:%s(%d): aarch64 not implemented\n",
- __FUNCTION__, __FILE__, __LINE__);
+ rel->r_offset = s->dofs_offset +
+ dofr[j].dofr_offset;
+ rel->r_info = ELF32_R_INFO(count + dep->de_global,
+ R_ARM_REL32);
#elif defined(__arm__)
/* XXX */
printf("%s:%s(%d): arm not implemented\n",
@@ -425,7 +426,10 @@ prepare_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf64_t *dep)
for (j = 0; j < nrel; j++) {
#if defined(__aarch64__)
-/* XXX */
+ rel->r_offset = s->dofs_offset +
+ dofr[j].dofr_offset;
+ rel->r_info = ELF64_R_INFO(count + dep->de_global,
+ R_AARCH64_PREL64);
#elif defined(__arm__)
/* XXX */
#elif defined(__mips__)
@@ -541,6 +545,8 @@ dump_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd)
elf_file.ehdr.e_machine = EM_SPARC;
#elif defined(__i386) || defined(__amd64)
elf_file.ehdr.e_machine = EM_386;
+#elif defined(__aarch64__)
+ elf_file.ehdr.e_machine = EM_AARCH64;
#endif
elf_file.ehdr.e_version = EV_CURRENT;
elf_file.ehdr.e_shoff = sizeof (Elf32_Ehdr);
@@ -687,6 +693,8 @@ dump_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd)
elf_file.ehdr.e_machine = EM_SPARCV9;
#elif defined(__i386) || defined(__amd64)
elf_file.ehdr.e_machine = EM_AMD64;
+#elif defined(__aarch64__)
+ elf_file.ehdr.e_machine = EM_AARCH64;
#endif
elf_file.ehdr.e_version = EV_CURRENT;
elf_file.ehdr.e_shoff = sizeof (Elf64_Ehdr);
@@ -802,14 +810,66 @@ dt_symtab_lookup(Elf_Data *data_sym, int start, int end, uintptr_t addr,
}
#if defined(__aarch64__)
-/* XXX */
+#define DT_OP_NOP 0xd503201f
+#define DT_OP_RET 0xd65f03c0
+#define DT_OP_CALL26 0x94000000
+#define DT_OP_JUMP26 0x14000000
+
static int
dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela,
uint32_t *off)
{
- printf("%s:%s(%d): aarch64 not implemented\n", __FUNCTION__, __FILE__,
- __LINE__);
- return (-1);
+ uint32_t *ip;
+
+ /*
+ * Ensure that the offset is aligned on an instruction boundary.
+ */
+ if ((rela->r_offset & (sizeof (uint32_t) - 1)) != 0)
+ return (-1);
+
+ /*
+ * We only know about some specific relocation types.
+ * We also recognize relocation type NONE, since that gets used for
+ * relocations of USDT probes, and we might be re-processing a file.
+ */
+ if (GELF_R_TYPE(rela->r_info) != R_AARCH64_CALL26 &&
+ GELF_R_TYPE(rela->r_info) != R_AARCH64_JUMP26 &&
+ GELF_R_TYPE(rela->r_info) != R_AARCH64_NONE)
+ return (-1);
+
+ ip = (uint32_t *)(p + rela->r_offset);
+
+ /*
+ * We may have already processed this object file in an earlier linker
+ * invocation. Check to see if the present instruction sequence matches
+ * the one we would install below.
+ */
+ if (ip[0] == DT_OP_NOP || ip[0] == DT_OP_RET)
+ return (0);
+
+ /*
+ * We only expect call instructions with a displacement of 0, or a jump
+ * instruction acting as a tail call.
+ */
+ if (ip[0] != DT_OP_CALL26 && ip[0] != DT_OP_JUMP26) {
+ dt_dprintf("found %x instead of a call or jmp instruction at "
+ "%llx\n", ip[0], (u_longlong_t)rela->r_offset);
+ return (-1);
+ }
+
+ /*
+ * On arm64, we do not have to differentiate between regular probes and
+ * is-enabled probes. Both cases are encoded as a regular branch for
+ * non-tail call locations, and a jump for tail call locations. Calls
+ * are to be converted into a no-op whereas jumps should become a
+ * return.
+ */
+ if (ip[0] == DT_OP_CALL26)
+ ip[0] = DT_OP_NOP;
+ else
+ ip[0] = DT_OP_RET;
+
+ return (0);
}
#elif defined(__arm__)
/* XXX */
@@ -1254,6 +1314,8 @@ process_obj(dtrace_hdl_t *dtp, const char *obj, int *eprobesp)
emachine1 = emachine2 = EM_SPARCV9;
#elif defined(__i386) || defined(__amd64)
emachine1 = emachine2 = EM_AMD64;
+#elif defined(__aarch64__)
+ emachine1 = emachine2 = EM_AARCH64;
#endif
symsize = sizeof (Elf64_Sym);
} else {