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x86/cfi,bpf: Fix bpf_callback_t CFI

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Where the main BPF program is expected to match bpf_func_t,
sub-programs are expected to match bpf_callback_t.

This fixes things like:

tools/testing/selftests/bpf/progs/bloom_filter_bench.c:

           bpf_for_each_map_elem(&array_map, bloom_callback, &data, 0);

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20231215092707.451956710@infradead.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Peter Zijlstra 2023-12-15 10:12:19 +01:00 committed by Alexei Starovoitov
parent 4f9087f166
commit e72d88d18d
3 changed files with 30 additions and 8 deletions
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2
arch/x86/include/asm/cfi.h
View file

@ -106,6 +106,7 @@ struct pt_regs;
enum bug_trap_type handle_cfi_failure(struct pt_regs *regs);
#define __bpfcall
extern u32 cfi_bpf_hash;
extern u32 cfi_bpf_subprog_hash;
static inline int cfi_get_offset(void)
{
@ -128,6 +129,7 @@ static inline enum bug_trap_type handle_cfi_failure(struct pt_regs *regs)
return BUG_TRAP_TYPE_NONE;
}
#define cfi_bpf_hash 0U
#define cfi_bpf_subprog_hash 0U
#endif /* CONFIG_CFI_CLANG */
#endif /* _ASM_X86_CFI_H */

18
arch/x86/kernel/alternative.c
View file

@ -866,6 +866,23 @@ asm (
" .size cfi_bpf_hash, 4 \n"
" .popsection \n"
);
/* Must match bpf_callback_t */
extern u64 __bpf_callback_fn(u64, u64, u64, u64, u64);
__ADDRESSABLE(__bpf_callback_fn);
/* u32 __ro_after_init cfi_bpf_subprog_hash = __kcfi_typeid___bpf_callback_fn; */
asm (
" .pushsection .data..ro_after_init,\"aw\",@progbits \n"
" .type cfi_bpf_subprog_hash,@object \n"
" .globl cfi_bpf_subprog_hash \n"
" .p2align 2, 0x0 \n"
"cfi_bpf_subprog_hash: \n"
" .long __kcfi_typeid___bpf_callback_fn \n"
" .size cfi_bpf_subprog_hash, 4 \n"
" .popsection \n"
);
#endif
#ifdef CONFIG_FINEIBT
@ -1181,6 +1198,7 @@ static void __apply_fineibt(s32 *start_retpoline, s32 *end_retpoline,
if (builtin) {
cfi_seed = get_random_u32();
cfi_bpf_hash = cfi_rehash(cfi_bpf_hash);
cfi_bpf_subprog_hash = cfi_rehash(cfi_bpf_subprog_hash);
}
ret = cfi_rand_preamble(start_cfi, end_cfi);

18
arch/x86/net/bpf_jit_comp.c
View file

@ -312,12 +312,13 @@ static void pop_callee_regs(u8 **pprog, bool *callee_regs_used)
* in arch/x86/kernel/alternative.c
*/
static void emit_fineibt(u8 **pprog)
static void emit_fineibt(u8 **pprog, bool is_subprog)
{
u32 hash = is_subprog ? cfi_bpf_subprog_hash : cfi_bpf_hash;
u8 *prog = *pprog;
EMIT_ENDBR();
EMIT3_off32(0x41, 0x81, 0xea, cfi_bpf_hash); /* subl $hash, %r10d */
EMIT3_off32(0x41, 0x81, 0xea, hash); /* subl $hash, %r10d */
EMIT2(0x74, 0x07); /* jz.d8 +7 */
EMIT2(0x0f, 0x0b); /* ud2 */
EMIT1(0x90); /* nop */
@ -326,11 +327,12 @@ static void emit_fineibt(u8 **pprog)
*pprog = prog;
}
static void emit_kcfi(u8 **pprog)
static void emit_kcfi(u8 **pprog, bool is_subprog)
{
u32 hash = is_subprog ? cfi_bpf_subprog_hash : cfi_bpf_hash;
u8 *prog = *pprog;
EMIT1_off32(0xb8, cfi_bpf_hash); /* movl $hash, %eax */
EMIT1_off32(0xb8, hash); /* movl $hash, %eax */
#ifdef CONFIG_CALL_PADDING
EMIT1(0x90);
EMIT1(0x90);
@ -349,17 +351,17 @@ static void emit_kcfi(u8 **pprog)
*pprog = prog;
}
static void emit_cfi(u8 **pprog)
static void emit_cfi(u8 **pprog, bool is_subprog)
{
u8 *prog = *pprog;
switch (cfi_mode) {
case CFI_FINEIBT:
emit_fineibt(&prog);
emit_fineibt(&prog, is_subprog);
break;
case CFI_KCFI:
emit_kcfi(&prog);
emit_kcfi(&prog, is_subprog);
break;
default:
@ -381,7 +383,7 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf,
{
u8 *prog = *pprog;
emit_cfi(&prog);
emit_cfi(&prog, is_subprog);
/* BPF trampoline can be made to work without these nops,
* but let's waste 5 bytes for now and optimize later
*/