From 5edf6a1983b90371da888ca86493937ec1c8a2b5 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 8 Dec 2021 20:32:43 +0100 Subject: bpf, x64: Replace some stack_size usage with offset variables As suggested by Andrii, adding variables for registers and ip address offsets, which makes the code more clear, rather than abusing single stack_size variable for everything. Also describing the stack layout in the comment. There is no function change. Suggested-by: Andrii Nakryiko Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20211208193245.172141-4-jolsa@kernel.org --- arch/x86/net/bpf_jit_comp.c | 42 ++++++++++++++++++++++++++++-------------- 1 file changed, 28 insertions(+), 14 deletions(-) (limited to 'arch') diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 1d7b0c69b644..10fab8cb3fb5 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -1941,7 +1941,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i void *orig_call) { int ret, i, nr_args = m->nr_args; - int stack_size = nr_args * 8; + int regs_off, ip_off, stack_size = nr_args * 8; struct bpf_tramp_progs *fentry = &tprogs[BPF_TRAMP_FENTRY]; struct bpf_tramp_progs *fexit = &tprogs[BPF_TRAMP_FEXIT]; struct bpf_tramp_progs *fmod_ret = &tprogs[BPF_TRAMP_MODIFY_RETURN]; @@ -1956,14 +1956,33 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i if (!is_valid_bpf_tramp_flags(flags)) return -EINVAL; + /* Generated trampoline stack layout: + * + * RBP + 8 [ return address ] + * RBP + 0 [ RBP ] + * + * RBP - 8 [ return value ] BPF_TRAMP_F_CALL_ORIG or + * BPF_TRAMP_F_RET_FENTRY_RET flags + * + * [ reg_argN ] always + * [ ... ] + * RBP - regs_off [ reg_arg1 ] program's ctx pointer + * + * RBP - ip_off [ traced function ] BPF_TRAMP_F_IP_ARG flag + */ + /* room for return value of orig_call or fentry prog */ save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET); if (save_ret) stack_size += 8; + regs_off = stack_size; + if (flags & BPF_TRAMP_F_IP_ARG) stack_size += 8; /* room for IP address argument */ + ip_off = stack_size; + if (flags & BPF_TRAMP_F_SKIP_FRAME) /* skip patched call instruction and point orig_call to actual * body of the kernel function. @@ -1981,19 +2000,14 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i /* Store IP address of the traced function: * mov rax, QWORD PTR [rbp + 8] * sub rax, X86_PATCH_SIZE - * mov QWORD PTR [rbp - stack_size], rax + * mov QWORD PTR [rbp - ip_off], rax */ emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, 8); EMIT4(0x48, 0x83, 0xe8, X86_PATCH_SIZE); - emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -stack_size); - - /* Continue with stack_size for regs storage, stack will - * be correctly restored with 'leave' instruction. - */ - stack_size -= 8; + emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -ip_off); } - save_regs(m, &prog, nr_args, stack_size); + save_regs(m, &prog, nr_args, regs_off); if (flags & BPF_TRAMP_F_CALL_ORIG) { /* arg1: mov rdi, im */ @@ -2005,7 +2019,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i } if (fentry->nr_progs) - if (invoke_bpf(m, &prog, fentry, stack_size, + if (invoke_bpf(m, &prog, fentry, regs_off, flags & BPF_TRAMP_F_RET_FENTRY_RET)) return -EINVAL; @@ -2015,7 +2029,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i if (!branches) return -ENOMEM; - if (invoke_bpf_mod_ret(m, &prog, fmod_ret, stack_size, + if (invoke_bpf_mod_ret(m, &prog, fmod_ret, regs_off, branches)) { ret = -EINVAL; goto cleanup; @@ -2023,7 +2037,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i } if (flags & BPF_TRAMP_F_CALL_ORIG) { - restore_regs(m, &prog, nr_args, stack_size); + restore_regs(m, &prog, nr_args, regs_off); /* call original function */ if (emit_call(&prog, orig_call, prog)) { @@ -2053,13 +2067,13 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i } if (fexit->nr_progs) - if (invoke_bpf(m, &prog, fexit, stack_size, false)) { + if (invoke_bpf(m, &prog, fexit, regs_off, false)) { ret = -EINVAL; goto cleanup; } if (flags & BPF_TRAMP_F_RESTORE_REGS) - restore_regs(m, &prog, nr_args, stack_size); + restore_regs(m, &prog, nr_args, regs_off); /* This needs to be done regardless. If there were fmod_ret programs, * the return value is only updated on the stack and still needs to be -- cgit v1.2.3 From f92c1e183604c20ce00eb889315fdaa8f2d9e509 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 8 Dec 2021 20:32:44 +0100 Subject: bpf: Add get_func_[arg|ret|arg_cnt] helpers Adding following helpers for tracing programs: Get n-th argument of the traced function: long bpf_get_func_arg(void *ctx, u32 n, u64 *value) Get return value of the traced function: long bpf_get_func_ret(void *ctx, u64 *value) Get arguments count of the traced function: long bpf_get_func_arg_cnt(void *ctx) The trampoline now stores number of arguments on ctx-8 address, so it's easy to verify argument index and find return value argument's position. Moving function ip address on the trampoline stack behind the number of functions arguments, so it's now stored on ctx-16 address if it's needed. All helpers above are inlined by verifier. Also bit unrelated small change - using newly added function bpf_prog_has_trampoline in check_get_func_ip. Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20211208193245.172141-5-jolsa@kernel.org --- arch/x86/net/bpf_jit_comp.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 10fab8cb3fb5..4bbcded07415 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -1941,7 +1941,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i void *orig_call) { int ret, i, nr_args = m->nr_args; - int regs_off, ip_off, stack_size = nr_args * 8; + int regs_off, ip_off, args_off, stack_size = nr_args * 8; struct bpf_tramp_progs *fentry = &tprogs[BPF_TRAMP_FENTRY]; struct bpf_tramp_progs *fexit = &tprogs[BPF_TRAMP_FEXIT]; struct bpf_tramp_progs *fmod_ret = &tprogs[BPF_TRAMP_MODIFY_RETURN]; @@ -1968,6 +1968,8 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i * [ ... ] * RBP - regs_off [ reg_arg1 ] program's ctx pointer * + * RBP - args_off [ args count ] always + * * RBP - ip_off [ traced function ] BPF_TRAMP_F_IP_ARG flag */ @@ -1978,6 +1980,10 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i regs_off = stack_size; + /* args count */ + stack_size += 8; + args_off = stack_size; + if (flags & BPF_TRAMP_F_IP_ARG) stack_size += 8; /* room for IP address argument */ @@ -1996,6 +2002,13 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i EMIT4(0x48, 0x83, 0xEC, stack_size); /* sub rsp, stack_size */ EMIT1(0x53); /* push rbx */ + /* Store number of arguments of the traced function: + * mov rax, nr_args + * mov QWORD PTR [rbp - args_off], rax + */ + emit_mov_imm64(&prog, BPF_REG_0, 0, (u32) nr_args); + emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -args_off); + if (flags & BPF_TRAMP_F_IP_ARG) { /* Store IP address of the traced function: * mov rax, QWORD PTR [rbp + 8] -- cgit v1.2.3 From f7ea534a0920dbaf71a8003936e178e14ec9271d Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Wed, 15 Dec 2021 18:55:36 -0800 Subject: add includes masked by cgroup -> bpf dependency cgroup pulls in BPF which pulls in a lot of includes. We're about to break that chain so fix those who were depending on it. Signed-off-by: Jakub Kicinski Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20211216025538.1649516-2-kuba@kernel.org --- arch/s390/mm/hugetlbpage.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch') diff --git a/arch/s390/mm/hugetlbpage.c b/arch/s390/mm/hugetlbpage.c index da36d13ffc16..082793d497ec 100644 --- a/arch/s390/mm/hugetlbpage.c +++ b/arch/s390/mm/hugetlbpage.c @@ -9,6 +9,7 @@ #define KMSG_COMPONENT "hugetlb" #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt +#include #include #include #include -- cgit v1.2.3