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Add libdtrace support for arm64 USDT probes.

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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 Küchemann <maciphone2@googlemail.com> (original)
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D22360
This commit is contained in:
Mark Johnston 2019-12-29 21:46:50 +00:00
parent 78347412c0
commit a2ea78495a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=356187
1 changed files with 70 additions and 8 deletions
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78
cddl/contrib/opensolaris/lib/libdtrace/common/dt_link.c
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@ -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 {