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60a6b2c78c
BPF verifier expects callback subprogs to return values from specified range (typically [0, 1]). This requires that r0 at exit is both precise (because we rely on specific value range) and is marked as read (otherwise state comparison will ignore such register as unimportant). Add a simple test that validates that all these conditions are enforced. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231202175705.885270-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
643 lines
20 KiB
C
643 lines
20 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
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#include <errno.h>
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#include <string.h>
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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#include "bpf_misc.h"
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#define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))
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int vals[] SEC(".data.vals") = {1, 2, 3, 4};
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__naked __noinline __used
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static unsigned long identity_subprog()
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{
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/* the simplest *static* 64-bit identity function */
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asm volatile (
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"r0 = r1;"
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"exit;"
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);
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}
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__noinline __used
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unsigned long global_identity_subprog(__u64 x)
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{
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/* the simplest *global* 64-bit identity function */
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return x;
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}
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__naked __noinline __used
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static unsigned long callback_subprog()
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{
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/* the simplest callback function */
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asm volatile (
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"r0 = 0;"
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"exit;"
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);
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}
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SEC("?raw_tp")
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__success __log_level(2)
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__msg("7: (0f) r1 += r0")
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__msg("mark_precise: frame0: regs=r0 stack= before 6: (bf) r1 = r7")
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__msg("mark_precise: frame0: regs=r0 stack= before 5: (27) r0 *= 4")
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__msg("mark_precise: frame0: regs=r0 stack= before 11: (95) exit")
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__msg("mark_precise: frame1: regs=r0 stack= before 10: (bf) r0 = r1")
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__msg("mark_precise: frame1: regs=r1 stack= before 4: (85) call pc+5")
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__msg("mark_precise: frame0: regs=r1 stack= before 3: (bf) r1 = r6")
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__msg("mark_precise: frame0: regs=r6 stack= before 2: (b7) r6 = 3")
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__naked int subprog_result_precise(void)
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{
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asm volatile (
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"r6 = 3;"
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/* pass r6 through r1 into subprog to get it back as r0;
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* this whole chain will have to be marked as precise later
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*/
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"r1 = r6;"
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"call identity_subprog;"
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/* now use subprog's returned value (which is a
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* r6 -> r1 -> r0 chain), as index into vals array, forcing
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* all of that to be known precisely
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*/
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"r0 *= 4;"
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"r1 = %[vals];"
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/* here r0->r1->r6 chain is forced to be precise and has to be
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* propagated back to the beginning, including through the
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* subprog call
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*/
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"r1 += r0;"
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"r0 = *(u32 *)(r1 + 0);"
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"exit;"
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:
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: __imm_ptr(vals)
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: __clobber_common, "r6"
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);
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}
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SEC("?raw_tp")
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__success __log_level(2)
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__msg("9: (0f) r1 += r0")
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__msg("mark_precise: frame0: last_idx 9 first_idx 0")
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__msg("mark_precise: frame0: regs=r0 stack= before 8: (bf) r1 = r7")
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__msg("mark_precise: frame0: regs=r0 stack= before 7: (27) r0 *= 4")
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__msg("mark_precise: frame0: regs=r0 stack= before 5: (a5) if r0 < 0x4 goto pc+1")
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__msg("mark_precise: frame0: regs=r0 stack= before 4: (85) call pc+7")
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__naked int global_subprog_result_precise(void)
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{
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asm volatile (
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"r6 = 3;"
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/* pass r6 through r1 into subprog to get it back as r0;
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* given global_identity_subprog is global, precision won't
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* propagate all the way back to r6
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*/
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"r1 = r6;"
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"call global_identity_subprog;"
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/* now use subprog's returned value (which is unknown now, so
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* we need to clamp it), as index into vals array, forcing r0
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* to be marked precise (with no effect on r6, though)
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*/
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"if r0 < %[vals_arr_sz] goto 1f;"
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"r0 = %[vals_arr_sz] - 1;"
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"1:"
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"r0 *= 4;"
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"r1 = %[vals];"
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/* here r0 is forced to be precise and has to be
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* propagated back to the global subprog call, but it
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* shouldn't go all the way to mark r6 as precise
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*/
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"r1 += r0;"
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"r0 = *(u32 *)(r1 + 0);"
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"exit;"
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:
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: __imm_ptr(vals),
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__imm_const(vals_arr_sz, ARRAY_SIZE(vals))
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: __clobber_common, "r6"
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);
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}
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__naked __noinline __used
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static unsigned long loop_callback_bad()
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{
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/* bpf_loop() callback that can return values outside of [0, 1] range */
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asm volatile (
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"call %[bpf_get_prandom_u32];"
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"if r0 s> 1000 goto 1f;"
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"r0 = 0;"
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"1:"
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"goto +0;" /* checkpoint */
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/* bpf_loop() expects [0, 1] values, so branch above skipping
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* r0 = 0; should lead to a failure, but if exit instruction
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* doesn't enforce r0's precision, this callback will be
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* successfully verified
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*/
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"exit;"
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:
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: __imm(bpf_get_prandom_u32)
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: __clobber_common
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);
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}
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SEC("?raw_tp")
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__failure __log_level(2)
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__flag(BPF_F_TEST_STATE_FREQ)
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/* check that fallthrough code path marks r0 as precise */
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__msg("mark_precise: frame1: regs=r0 stack= before 11: (b7) r0 = 0")
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/* check that we have branch code path doing its own validation */
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__msg("from 10 to 12: frame1: R0=scalar(smin=umin=1001")
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/* check that branch code path marks r0 as precise, before failing */
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__msg("mark_precise: frame1: regs=r0 stack= before 9: (85) call bpf_get_prandom_u32#7")
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__msg("At callback return the register R0 has value (0x0; 0x7fffffffffffffff) should have been in (0x0; 0x1)")
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__naked int callback_precise_return_fail(void)
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{
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asm volatile (
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"r1 = 1;" /* nr_loops */
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"r2 = %[loop_callback_bad];" /* callback_fn */
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"r3 = 0;" /* callback_ctx */
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"r4 = 0;" /* flags */
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"call %[bpf_loop];"
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"r0 = 0;"
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"exit;"
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:
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: __imm_ptr(loop_callback_bad),
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__imm(bpf_loop)
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: __clobber_common
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);
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}
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SEC("?raw_tp")
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__success __log_level(2)
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/* First simulated path does not include callback body,
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* r1 and r4 are always precise for bpf_loop() calls.
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*/
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__msg("9: (85) call bpf_loop#181")
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__msg("mark_precise: frame0: last_idx 9 first_idx 9 subseq_idx -1")
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__msg("mark_precise: frame0: parent state regs=r4 stack=:")
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__msg("mark_precise: frame0: last_idx 8 first_idx 0 subseq_idx 9")
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__msg("mark_precise: frame0: regs=r4 stack= before 8: (b7) r4 = 0")
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__msg("mark_precise: frame0: last_idx 9 first_idx 9 subseq_idx -1")
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__msg("mark_precise: frame0: parent state regs=r1 stack=:")
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__msg("mark_precise: frame0: last_idx 8 first_idx 0 subseq_idx 9")
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__msg("mark_precise: frame0: regs=r1 stack= before 8: (b7) r4 = 0")
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__msg("mark_precise: frame0: regs=r1 stack= before 7: (b7) r3 = 0")
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__msg("mark_precise: frame0: regs=r1 stack= before 6: (bf) r2 = r8")
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__msg("mark_precise: frame0: regs=r1 stack= before 5: (bf) r1 = r6")
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__msg("mark_precise: frame0: regs=r6 stack= before 4: (b7) r6 = 3")
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/* r6 precision propagation */
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__msg("14: (0f) r1 += r6")
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__msg("mark_precise: frame0: last_idx 14 first_idx 9")
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__msg("mark_precise: frame0: regs=r6 stack= before 13: (bf) r1 = r7")
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__msg("mark_precise: frame0: regs=r6 stack= before 12: (27) r6 *= 4")
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__msg("mark_precise: frame0: regs=r6 stack= before 11: (25) if r6 > 0x3 goto pc+4")
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__msg("mark_precise: frame0: regs=r6 stack= before 10: (bf) r6 = r0")
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__msg("mark_precise: frame0: regs=r0 stack= before 9: (85) call bpf_loop")
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/* State entering callback body popped from states stack */
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__msg("from 9 to 17: frame1:")
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__msg("17: frame1: R1=scalar() R2=0 R10=fp0 cb")
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__msg("17: (b7) r0 = 0")
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__msg("18: (95) exit")
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__msg("returning from callee:")
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__msg("to caller at 9:")
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__msg("frame 0: propagating r1,r4")
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__msg("mark_precise: frame0: last_idx 9 first_idx 9 subseq_idx -1")
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__msg("mark_precise: frame0: regs=r1,r4 stack= before 18: (95) exit")
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__msg("from 18 to 9: safe")
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__naked int callback_result_precise(void)
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{
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asm volatile (
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"r6 = 3;"
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/* call subprog and use result; r0 shouldn't propagate back to
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* callback_subprog
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*/
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"r1 = r6;" /* nr_loops */
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"r2 = %[callback_subprog];" /* callback_fn */
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"r3 = 0;" /* callback_ctx */
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"r4 = 0;" /* flags */
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"call %[bpf_loop];"
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"r6 = r0;"
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"if r6 > 3 goto 1f;"
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"r6 *= 4;"
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"r1 = %[vals];"
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/* here r6 is forced to be precise and has to be propagated
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* back to the bpf_loop() call, but not beyond
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*/
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"r1 += r6;"
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"r0 = *(u32 *)(r1 + 0);"
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"1:"
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"exit;"
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:
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: __imm_ptr(vals),
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__imm_ptr(callback_subprog),
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__imm(bpf_loop)
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: __clobber_common, "r6"
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);
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}
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SEC("?raw_tp")
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__success __log_level(2)
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__msg("7: (0f) r1 += r6")
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__msg("mark_precise: frame0: last_idx 7 first_idx 0")
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__msg("mark_precise: frame0: regs=r6 stack= before 6: (bf) r1 = r7")
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__msg("mark_precise: frame0: regs=r6 stack= before 5: (27) r6 *= 4")
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__msg("mark_precise: frame0: regs=r6 stack= before 11: (95) exit")
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__msg("mark_precise: frame1: regs= stack= before 10: (bf) r0 = r1")
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__msg("mark_precise: frame1: regs= stack= before 4: (85) call pc+5")
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__msg("mark_precise: frame0: regs=r6 stack= before 3: (b7) r1 = 0")
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__msg("mark_precise: frame0: regs=r6 stack= before 2: (b7) r6 = 3")
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__naked int parent_callee_saved_reg_precise(void)
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{
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asm volatile (
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"r6 = 3;"
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/* call subprog and ignore result; we need this call only to
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* complicate jump history
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*/
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"r1 = 0;"
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"call identity_subprog;"
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"r6 *= 4;"
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"r1 = %[vals];"
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/* here r6 is forced to be precise and has to be propagated
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* back to the beginning, handling (and ignoring) subprog call
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*/
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"r1 += r6;"
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"r0 = *(u32 *)(r1 + 0);"
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"exit;"
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:
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: __imm_ptr(vals)
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: __clobber_common, "r6"
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);
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}
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SEC("?raw_tp")
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__success __log_level(2)
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__msg("7: (0f) r1 += r6")
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__msg("mark_precise: frame0: last_idx 7 first_idx 0")
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__msg("mark_precise: frame0: regs=r6 stack= before 6: (bf) r1 = r7")
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__msg("mark_precise: frame0: regs=r6 stack= before 5: (27) r6 *= 4")
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__msg("mark_precise: frame0: regs=r6 stack= before 4: (85) call pc+5")
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__msg("mark_precise: frame0: regs=r6 stack= before 3: (b7) r1 = 0")
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__msg("mark_precise: frame0: regs=r6 stack= before 2: (b7) r6 = 3")
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__naked int parent_callee_saved_reg_precise_global(void)
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{
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asm volatile (
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"r6 = 3;"
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/* call subprog and ignore result; we need this call only to
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* complicate jump history
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*/
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"r1 = 0;"
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"call global_identity_subprog;"
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"r6 *= 4;"
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"r1 = %[vals];"
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/* here r6 is forced to be precise and has to be propagated
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* back to the beginning, handling (and ignoring) subprog call
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*/
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"r1 += r6;"
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"r0 = *(u32 *)(r1 + 0);"
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"exit;"
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:
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: __imm_ptr(vals)
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: __clobber_common, "r6"
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);
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}
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SEC("?raw_tp")
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__success __log_level(2)
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/* First simulated path does not include callback body */
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__msg("12: (0f) r1 += r6")
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__msg("mark_precise: frame0: last_idx 12 first_idx 9")
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__msg("mark_precise: frame0: regs=r6 stack= before 11: (bf) r1 = r7")
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__msg("mark_precise: frame0: regs=r6 stack= before 10: (27) r6 *= 4")
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__msg("mark_precise: frame0: regs=r6 stack= before 9: (85) call bpf_loop")
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__msg("mark_precise: frame0: parent state regs=r6 stack=:")
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__msg("mark_precise: frame0: last_idx 8 first_idx 0 subseq_idx 9")
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__msg("mark_precise: frame0: regs=r6 stack= before 8: (b7) r4 = 0")
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__msg("mark_precise: frame0: regs=r6 stack= before 7: (b7) r3 = 0")
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__msg("mark_precise: frame0: regs=r6 stack= before 6: (bf) r2 = r8")
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__msg("mark_precise: frame0: regs=r6 stack= before 5: (b7) r1 = 1")
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__msg("mark_precise: frame0: regs=r6 stack= before 4: (b7) r6 = 3")
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/* State entering callback body popped from states stack */
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__msg("from 9 to 15: frame1:")
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__msg("15: frame1: R1=scalar() R2=0 R10=fp0 cb")
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__msg("15: (b7) r0 = 0")
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__msg("16: (95) exit")
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__msg("returning from callee:")
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__msg("to caller at 9:")
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/* r1, r4 are always precise for bpf_loop(),
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* r6 was marked before backtracking to callback body.
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*/
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__msg("frame 0: propagating r1,r4,r6")
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__msg("mark_precise: frame0: last_idx 9 first_idx 9 subseq_idx -1")
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__msg("mark_precise: frame0: regs=r1,r4,r6 stack= before 16: (95) exit")
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__msg("mark_precise: frame1: regs= stack= before 15: (b7) r0 = 0")
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__msg("mark_precise: frame1: regs= stack= before 9: (85) call bpf_loop")
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__msg("mark_precise: frame0: parent state regs= stack=:")
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__msg("from 16 to 9: safe")
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__naked int parent_callee_saved_reg_precise_with_callback(void)
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{
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asm volatile (
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"r6 = 3;"
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/* call subprog and ignore result; we need this call only to
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* complicate jump history
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*/
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"r1 = 1;" /* nr_loops */
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"r2 = %[callback_subprog];" /* callback_fn */
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"r3 = 0;" /* callback_ctx */
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"r4 = 0;" /* flags */
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"call %[bpf_loop];"
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"r6 *= 4;"
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"r1 = %[vals];"
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/* here r6 is forced to be precise and has to be propagated
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* back to the beginning, handling (and ignoring) callback call
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*/
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"r1 += r6;"
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"r0 = *(u32 *)(r1 + 0);"
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"exit;"
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:
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: __imm_ptr(vals),
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__imm_ptr(callback_subprog),
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__imm(bpf_loop)
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: __clobber_common, "r6"
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);
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}
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SEC("?raw_tp")
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__success __log_level(2)
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__msg("9: (0f) r1 += r6")
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__msg("mark_precise: frame0: last_idx 9 first_idx 6")
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__msg("mark_precise: frame0: regs=r6 stack= before 8: (bf) r1 = r7")
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__msg("mark_precise: frame0: regs=r6 stack= before 7: (27) r6 *= 4")
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__msg("mark_precise: frame0: regs=r6 stack= before 6: (79) r6 = *(u64 *)(r10 -8)")
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__msg("mark_precise: frame0: parent state regs= stack=-8:")
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__msg("mark_precise: frame0: last_idx 13 first_idx 0")
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__msg("mark_precise: frame0: regs= stack=-8 before 13: (95) exit")
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__msg("mark_precise: frame1: regs= stack= before 12: (bf) r0 = r1")
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__msg("mark_precise: frame1: regs= stack= before 5: (85) call pc+6")
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__msg("mark_precise: frame0: regs= stack=-8 before 4: (b7) r1 = 0")
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__msg("mark_precise: frame0: regs= stack=-8 before 3: (7b) *(u64 *)(r10 -8) = r6")
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__msg("mark_precise: frame0: regs=r6 stack= before 2: (b7) r6 = 3")
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__naked int parent_stack_slot_precise(void)
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{
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asm volatile (
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/* spill reg */
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"r6 = 3;"
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"*(u64 *)(r10 - 8) = r6;"
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/* call subprog and ignore result; we need this call only to
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* complicate jump history
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*/
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"r1 = 0;"
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"call identity_subprog;"
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/* restore reg from stack; in this case we'll be carrying
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* stack mask when going back into subprog through jump
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* history
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*/
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"r6 = *(u64 *)(r10 - 8);"
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"r6 *= 4;"
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"r1 = %[vals];"
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/* here r6 is forced to be precise and has to be propagated
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* back to the beginning, handling (and ignoring) subprog call
|
|
*/
|
|
"r1 += r6;"
|
|
"r0 = *(u32 *)(r1 + 0);"
|
|
"exit;"
|
|
:
|
|
: __imm_ptr(vals)
|
|
: __clobber_common, "r6"
|
|
);
|
|
}
|
|
|
|
SEC("?raw_tp")
|
|
__success __log_level(2)
|
|
__msg("9: (0f) r1 += r6")
|
|
__msg("mark_precise: frame0: last_idx 9 first_idx 0")
|
|
__msg("mark_precise: frame0: regs=r6 stack= before 8: (bf) r1 = r7")
|
|
__msg("mark_precise: frame0: regs=r6 stack= before 7: (27) r6 *= 4")
|
|
__msg("mark_precise: frame0: regs=r6 stack= before 6: (79) r6 = *(u64 *)(r10 -8)")
|
|
__msg("mark_precise: frame0: regs= stack=-8 before 5: (85) call pc+6")
|
|
__msg("mark_precise: frame0: regs= stack=-8 before 4: (b7) r1 = 0")
|
|
__msg("mark_precise: frame0: regs= stack=-8 before 3: (7b) *(u64 *)(r10 -8) = r6")
|
|
__msg("mark_precise: frame0: regs=r6 stack= before 2: (b7) r6 = 3")
|
|
__naked int parent_stack_slot_precise_global(void)
|
|
{
|
|
asm volatile (
|
|
/* spill reg */
|
|
"r6 = 3;"
|
|
"*(u64 *)(r10 - 8) = r6;"
|
|
|
|
/* call subprog and ignore result; we need this call only to
|
|
* complicate jump history
|
|
*/
|
|
"r1 = 0;"
|
|
"call global_identity_subprog;"
|
|
|
|
/* restore reg from stack; in this case we'll be carrying
|
|
* stack mask when going back into subprog through jump
|
|
* history
|
|
*/
|
|
"r6 = *(u64 *)(r10 - 8);"
|
|
|
|
"r6 *= 4;"
|
|
"r1 = %[vals];"
|
|
/* here r6 is forced to be precise and has to be propagated
|
|
* back to the beginning, handling (and ignoring) subprog call
|
|
*/
|
|
"r1 += r6;"
|
|
"r0 = *(u32 *)(r1 + 0);"
|
|
"exit;"
|
|
:
|
|
: __imm_ptr(vals)
|
|
: __clobber_common, "r6"
|
|
);
|
|
}
|
|
|
|
SEC("?raw_tp")
|
|
__success __log_level(2)
|
|
/* First simulated path does not include callback body */
|
|
__msg("14: (0f) r1 += r6")
|
|
__msg("mark_precise: frame0: last_idx 14 first_idx 10")
|
|
__msg("mark_precise: frame0: regs=r6 stack= before 13: (bf) r1 = r7")
|
|
__msg("mark_precise: frame0: regs=r6 stack= before 12: (27) r6 *= 4")
|
|
__msg("mark_precise: frame0: regs=r6 stack= before 11: (79) r6 = *(u64 *)(r10 -8)")
|
|
__msg("mark_precise: frame0: regs= stack=-8 before 10: (85) call bpf_loop")
|
|
__msg("mark_precise: frame0: parent state regs= stack=-8:")
|
|
__msg("mark_precise: frame0: last_idx 9 first_idx 0 subseq_idx 10")
|
|
__msg("mark_precise: frame0: regs= stack=-8 before 9: (b7) r4 = 0")
|
|
__msg("mark_precise: frame0: regs= stack=-8 before 8: (b7) r3 = 0")
|
|
__msg("mark_precise: frame0: regs= stack=-8 before 7: (bf) r2 = r8")
|
|
__msg("mark_precise: frame0: regs= stack=-8 before 6: (bf) r1 = r6")
|
|
__msg("mark_precise: frame0: regs= stack=-8 before 5: (7b) *(u64 *)(r10 -8) = r6")
|
|
__msg("mark_precise: frame0: regs=r6 stack= before 4: (b7) r6 = 3")
|
|
/* State entering callback body popped from states stack */
|
|
__msg("from 10 to 17: frame1:")
|
|
__msg("17: frame1: R1=scalar() R2=0 R10=fp0 cb")
|
|
__msg("17: (b7) r0 = 0")
|
|
__msg("18: (95) exit")
|
|
__msg("returning from callee:")
|
|
__msg("to caller at 10:")
|
|
/* r1, r4 are always precise for bpf_loop(),
|
|
* fp-8 was marked before backtracking to callback body.
|
|
*/
|
|
__msg("frame 0: propagating r1,r4,fp-8")
|
|
__msg("mark_precise: frame0: last_idx 10 first_idx 10 subseq_idx -1")
|
|
__msg("mark_precise: frame0: regs=r1,r4 stack=-8 before 18: (95) exit")
|
|
__msg("mark_precise: frame1: regs= stack= before 17: (b7) r0 = 0")
|
|
__msg("mark_precise: frame1: regs= stack= before 10: (85) call bpf_loop#181")
|
|
__msg("mark_precise: frame0: parent state regs= stack=:")
|
|
__msg("from 18 to 10: safe")
|
|
__naked int parent_stack_slot_precise_with_callback(void)
|
|
{
|
|
asm volatile (
|
|
/* spill reg */
|
|
"r6 = 3;"
|
|
"*(u64 *)(r10 - 8) = r6;"
|
|
|
|
/* ensure we have callback frame in jump history */
|
|
"r1 = r6;" /* nr_loops */
|
|
"r2 = %[callback_subprog];" /* callback_fn */
|
|
"r3 = 0;" /* callback_ctx */
|
|
"r4 = 0;" /* flags */
|
|
"call %[bpf_loop];"
|
|
|
|
/* restore reg from stack; in this case we'll be carrying
|
|
* stack mask when going back into subprog through jump
|
|
* history
|
|
*/
|
|
"r6 = *(u64 *)(r10 - 8);"
|
|
|
|
"r6 *= 4;"
|
|
"r1 = %[vals];"
|
|
/* here r6 is forced to be precise and has to be propagated
|
|
* back to the beginning, handling (and ignoring) subprog call
|
|
*/
|
|
"r1 += r6;"
|
|
"r0 = *(u32 *)(r1 + 0);"
|
|
"exit;"
|
|
:
|
|
: __imm_ptr(vals),
|
|
__imm_ptr(callback_subprog),
|
|
__imm(bpf_loop)
|
|
: __clobber_common, "r6"
|
|
);
|
|
}
|
|
|
|
__noinline __used
|
|
static __u64 subprog_with_precise_arg(__u64 x)
|
|
{
|
|
return vals[x]; /* x is forced to be precise */
|
|
}
|
|
|
|
SEC("?raw_tp")
|
|
__success __log_level(2)
|
|
__msg("8: (0f) r2 += r1")
|
|
__msg("mark_precise: frame1: last_idx 8 first_idx 0")
|
|
__msg("mark_precise: frame1: regs=r1 stack= before 6: (18) r2 = ")
|
|
__msg("mark_precise: frame1: regs=r1 stack= before 5: (67) r1 <<= 2")
|
|
__msg("mark_precise: frame1: regs=r1 stack= before 2: (85) call pc+2")
|
|
__msg("mark_precise: frame0: regs=r1 stack= before 1: (bf) r1 = r6")
|
|
__msg("mark_precise: frame0: regs=r6 stack= before 0: (b7) r6 = 3")
|
|
__naked int subprog_arg_precise(void)
|
|
{
|
|
asm volatile (
|
|
"r6 = 3;"
|
|
"r1 = r6;"
|
|
/* subprog_with_precise_arg expects its argument to be
|
|
* precise, so r1->r6 will be marked precise from inside the
|
|
* subprog
|
|
*/
|
|
"call subprog_with_precise_arg;"
|
|
"r0 += r6;"
|
|
"exit;"
|
|
:
|
|
:
|
|
: __clobber_common, "r6"
|
|
);
|
|
}
|
|
|
|
/* r1 is pointer to stack slot;
|
|
* r2 is a register to spill into that slot
|
|
* subprog also spills r2 into its own stack slot
|
|
*/
|
|
__naked __noinline __used
|
|
static __u64 subprog_spill_reg_precise(void)
|
|
{
|
|
asm volatile (
|
|
/* spill to parent stack */
|
|
"*(u64 *)(r1 + 0) = r2;"
|
|
/* spill to subprog stack (we use -16 offset to avoid
|
|
* accidental confusion with parent's -8 stack slot in
|
|
* verifier log output)
|
|
*/
|
|
"*(u64 *)(r10 - 16) = r2;"
|
|
/* use both spills as return result to propagete precision everywhere */
|
|
"r0 = *(u64 *)(r10 - 16);"
|
|
"r2 = *(u64 *)(r1 + 0);"
|
|
"r0 += r2;"
|
|
"exit;"
|
|
);
|
|
}
|
|
|
|
SEC("?raw_tp")
|
|
__success __log_level(2)
|
|
/* precision backtracking can't currently handle stack access not through r10,
|
|
* so we won't be able to mark stack slot fp-8 as precise, and so will
|
|
* fallback to forcing all as precise
|
|
*/
|
|
__msg("mark_precise: frame0: falling back to forcing all scalars precise")
|
|
__naked int subprog_spill_into_parent_stack_slot_precise(void)
|
|
{
|
|
asm volatile (
|
|
"r6 = 1;"
|
|
|
|
/* pass pointer to stack slot and r6 to subprog;
|
|
* r6 will be marked precise and spilled into fp-8 slot, which
|
|
* also should be marked precise
|
|
*/
|
|
"r1 = r10;"
|
|
"r1 += -8;"
|
|
"r2 = r6;"
|
|
"call subprog_spill_reg_precise;"
|
|
|
|
/* restore reg from stack; in this case we'll be carrying
|
|
* stack mask when going back into subprog through jump
|
|
* history
|
|
*/
|
|
"r7 = *(u64 *)(r10 - 8);"
|
|
|
|
"r7 *= 4;"
|
|
"r1 = %[vals];"
|
|
/* here r7 is forced to be precise and has to be propagated
|
|
* back to the beginning, handling subprog call and logic
|
|
*/
|
|
"r1 += r7;"
|
|
"r0 = *(u32 *)(r1 + 0);"
|
|
"exit;"
|
|
:
|
|
: __imm_ptr(vals)
|
|
: __clobber_common, "r6", "r7"
|
|
);
|
|
}
|
|
|
|
__naked __noinline __used
|
|
static __u64 subprog_with_checkpoint(void)
|
|
{
|
|
asm volatile (
|
|
"r0 = 0;"
|
|
/* guaranteed checkpoint if BPF_F_TEST_STATE_FREQ is used */
|
|
"goto +0;"
|
|
"exit;"
|
|
);
|
|
}
|
|
|
|
char _license[] SEC("license") = "GPL";
|