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Date: Sun, 7 Mar 2021 12:12:31 +0100 From: Jiri Olsa <jolsa@...hat.com> To: Andrii Nakryiko <andrii.nakryiko@...il.com> Cc: Jiri Olsa <jolsa@...nel.org>, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andriin@...com>, Michael Ellerman <mpe@...erman.id.au>, "Naveen N . Rao" <naveen.n.rao@...ux.vnet.ibm.com>, Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>, Martin KaFai Lau <kafai@...com>, Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>, John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...omium.org>, Toke Høiland-Jørgensen <toke@...hat.com>, Yauheni Kaliuta <ykaliuta@...hat.com> Subject: Re: [PATCHv2 bpf-next] selftests/bpf: Fix test_attach_probe for powerpc uprobes On Sat, Mar 06, 2021 at 07:13:17PM -0800, Andrii Nakryiko wrote: > On Fri, Mar 5, 2021 at 5:42 AM Jiri Olsa <jolsa@...nel.org> wrote: > > > > When testing uprobes we the test gets GEP (Global Entry Point) > > address from kallsyms, but then the function is called locally > > so the uprobe is not triggered. > > > > Fixing this by adjusting the address to LEP (Local Entry Point) > > for powerpc arch plus instruction check stolen from ppc_function_entry > > function pointed out and explained by Michael and Naveen. > > > > Cc: Michael Ellerman <mpe@...erman.id.au> > > Cc: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com> > > Signed-off-by: Jiri Olsa <jolsa@...nel.org> > > --- > > .../selftests/bpf/prog_tests/attach_probe.c | 40 ++++++++++++++++++- > > 1 file changed, 39 insertions(+), 1 deletion(-) > > > > diff --git a/tools/testing/selftests/bpf/prog_tests/attach_probe.c b/tools/testing/selftests/bpf/prog_tests/attach_probe.c > > index a0ee87c8e1ea..9dc4e3dfbcf3 100644 > > --- a/tools/testing/selftests/bpf/prog_tests/attach_probe.c > > +++ b/tools/testing/selftests/bpf/prog_tests/attach_probe.c > > @@ -2,6 +2,44 @@ > > #include <test_progs.h> > > #include "test_attach_probe.skel.h" > > > > +#if defined(__powerpc64__) && defined(_CALL_ELF) && _CALL_ELF == 2 > > + > > +#define OP_RT_RA_MASK 0xffff0000UL > > +#define LIS_R2 0x3c400000UL > > +#define ADDIS_R2_R12 0x3c4c0000UL > > +#define ADDI_R2_R2 0x38420000UL > > + > > +static ssize_t get_offset(ssize_t addr, ssize_t base) > > +{ > > + u32 *insn = (u32 *) addr; > > + > > + /* > > + * A PPC64 ABIv2 function may have a local and a global entry > > + * point. We need to use the local entry point when patching > > + * functions, so identify and step over the global entry point > > + * sequence. > > + * > > + * The global entry point sequence is always of the form: > > + * > > + * addis r2,r12,XXXX > > + * addi r2,r2,XXXX > > + * > > + * A linker optimisation may convert the addis to lis: > > + * > > + * lis r2,XXXX > > + * addi r2,r2,XXXX > > + */ > > + if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) || > > + ((*insn & OP_RT_RA_MASK) == LIS_R2)) && > > + ((*(insn + 1) & OP_RT_RA_MASK) == ADDI_R2_R2)) > > + return (ssize_t)(insn + 2) - base; > > + else > > + return addr - base; > > +} > > +#else > > +#define get_offset(addr, base) (addr - base) > > I turned this into a static function, not sure why you preferred seemed simple enough to be dealt with in preprocessor, why bother compiler ;-) > #define here. Applied to bpf-next. thanks, jirka
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