// SPDX-License-Identifier: GPL-2.0

#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"

/* Read an uninitialized value from stack at a fixed offset */
SEC("socket")
__naked int read_uninit_stack_fixed_off(void *ctx)
{
        asm volatile ("                                 \
                r0 = 0;                                 \
                /* force stack depth to be 128 */       \
                *(u64*)(r10 - 128) = r1;                \
                r1 = *(u8 *)(r10 - 8 );                 \
                r0 += r1;                               \
                r1 = *(u8 *)(r10 - 11);                 \
                r1 = *(u8 *)(r10 - 13);                 \
                r1 = *(u8 *)(r10 - 15);                 \
                r1 = *(u16*)(r10 - 16);                 \
                r1 = *(u32*)(r10 - 32);                 \
                r1 = *(u64*)(r10 - 64);                 \
                /* read from a spill of a wrong size, it is a separate  \
                 * branch in check_stack_read_fixed_off()               \
                 */                                     \
                *(u32*)(r10 - 72) = r1;                 \
                r1 = *(u64*)(r10 - 72);                 \
                r0 = 0;                                 \
                exit;                                   \
"
                      ::: __clobber_all);
}

/* Read an uninitialized value from stack at a variable offset */
SEC("socket")
__naked int read_uninit_stack_var_off(void *ctx)
{
        asm volatile ("                                 \
                call %[bpf_get_prandom_u32];            \
                /* force stack depth to be 64 */        \
                *(u64*)(r10 - 64) = r0;                 \
                r0 = -r0;                               \
                /* give r0 a range [-31, -1] */         \
                if r0 s<= -32 goto exit_%=;             \
                if r0 s>= 0 goto exit_%=;               \
                /* access stack using r0 */             \
                r1 = r10;                               \
                r1 += r0;                               \
                r2 = *(u8*)(r1 + 0);                    \
exit_%=:        r0 = 0;                                 \
                exit;                                   \
"
                      :
                      : __imm(bpf_get_prandom_u32)
                      : __clobber_all);
}

static __noinline void dummy(void) {}

/* Pass a pointer to uninitialized stack memory to a helper.
 * Passed memory block should be marked as STACK_MISC after helper call.
 */
SEC("socket")
__log_level(7) __msg("fp-104=mmmmmmmm")
__naked int helper_uninit_to_misc(void *ctx)
{
        asm volatile ("                                 \
                /* force stack depth to be 128 */       \
                *(u64*)(r10 - 128) = r1;                \
                r1 = r10;                               \
                r1 += -128;                             \
                r2 = 32;                                \
                r3 = 0;                                 \
                call %[bpf_probe_read_user];            \
                /* Call to dummy() forces print_verifier_state(..., true),      \
                 * thus showing the stack state, matched by __msg().            \
                 */                                     \
                call %[dummy];                          \
                r0 = 0;                                 \
                exit;                                   \
"
                      :
                      : __imm(bpf_probe_read_user),
                        __imm(dummy)
                      : __clobber_all);
}

char _license[] SEC("license") = "GPL";