Commit b4406e10 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'follow-up-for-__jited-test-tag' 

Eduard Zingerman says:

====================
follow up for __jited test tag

This patch-set is a collection of follow-ups for
"__jited test tag to check disassembly after jit" series (see [1]).

First patch is most important:
as it turns out, I broke all test_loader based tests for s390 CI.
E.g. see log [2] for s390 execution of test_progs,
note all 'verivier_*' tests being skipped.
This happens because of incorrect handling of corner case when
get_current_arch() does not know which architecture to return.

Second patch makes matching of function return sequence in
verifier_tailcall_jit more flexible:

    -__jited("	retq")
    +__jited("	{{(retq|jmp	0x)}}")

The difference could be seen with and w/o mitigations=off boot
parameter for test VM (CI runs with mitigations=off, hence it
generates retq).

Third patch addresses Alexei's request to add #define and a comment in
jit_disasm_helpers.c.

[1] https://lore.kernel.org/bpf/20240820102357.3372779-1-eddyz87@gmail.com/
[2] https://github.com/kernel-patches/bpf/actions/runs/10518445973/job/29144511595
====================

Link: https://lore.kernel.org/r/20240823080644.263943-1-eddyz87@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents 7559a7a8 21a56fc5

tools/testing/selftests/bpf/jit_disasm_helpers.c

+14 −3
Original line number Diff line number Diff line
@@ -16,6 +16,11 @@ 
 */

#define MAX_LOCAL_LABELS 32



/* Local labels are encoded as 'L42', this requires 4 bytes of storage:

 * 3 characters + zero byte

 */

#define LOCAL_LABEL_LEN 4



static bool llvm_initialized;



struct local_labels {
@@ -23,7 +28,7 @@ struct local_labels { 
	__u32 prog_len;

	__u32 cnt;

	__u32 pcs[MAX_LOCAL_LABELS];

	char names[MAX_LOCAL_LABELS][4];

	char names[MAX_LOCAL_LABELS][LOCAL_LABEL_LEN];

};



static const char *lookup_symbol(void *data, uint64_t ref_value, uint64_t *ref_type,
@@ -118,8 +123,14 @@ static int disasm_one_func(FILE *text_out, uint8_t *image, __u32 len) 
	}

	qsort(labels.pcs, labels.cnt, sizeof(*labels.pcs), cmp_u32);

	for (i = 0; i < labels.cnt; ++i)

		/* use (i % 100) to avoid format truncation warning */

		snprintf(labels.names[i], sizeof(labels.names[i]), "L%d", i % 100);

		/* gcc is unable to infer upper bound for labels.cnt and assumes

		 * it to be U32_MAX. U32_MAX takes 10 decimal digits.

		 * snprintf below prints into labels.names[*],

		 * which has space only for two digits and a letter.

		 * To avoid truncation warning use (i % MAX_LOCAL_LABELS),

		 * which informs gcc about printed value upper bound.

		 */

		snprintf(labels.names[i], sizeof(labels.names[i]), "L%d", i % MAX_LOCAL_LABELS);



	/* now print with labels */

	labels.print_phase = true;

tools/testing/selftests/bpf/progs/verifier_tailcall_jit.c

+2 −2
Original line number Diff line number Diff line
@@ -59,7 +59,7 @@ __jited(" movq -0x10(%rbp), %rax") 
__jited("	callq	0x{{.*}}")		/* call to sub()          */

__jited("	xorl	%eax, %eax")

__jited("	leave")

__jited("	retq")

__jited("	{{(retq|jmp	0x)}}")		/* return or jump to rethunk */

__jited("...")

/* subprogram entry for sub(), regular function prologue */

__jited("	endbr64")
@@ -89,7 +89,7 @@ __jited(" popq %rax") 
__jited("	popq	%rax")

__jited("	jmp	{{.*}}")		/* jump to tail call tgt   */

__jited("L0:	leave")

__jited("	retq")

__jited("	{{(retq|jmp	0x)}}")		/* return or jump to rethunk */

SEC("tc")

__naked int main(void)

{

tools/testing/selftests/bpf/test_loader.c

+5 −4
Original line number Diff line number Diff line
@@ -336,9 +336,10 @@ static const char *skip_dynamic_pfx(const char *s, const char *pfx) 
}



enum arch {

	ARCH_X86_64	= 0x1,

	ARCH_ARM64	= 0x2,

	ARCH_RISCV64	= 0x4,

	ARCH_UNKNOWN	= 0x1,

	ARCH_X86_64	= 0x2,

	ARCH_ARM64	= 0x4,

	ARCH_RISCV64	= 0x8,

};



static int get_current_arch(void)
@@ -350,7 +351,7 @@ static int get_current_arch(void) 
#elif defined(__riscv) && __riscv_xlen == 64

	return ARCH_RISCV64;

#endif

	return 0;

	return ARCH_UNKNOWN;

}



/* Uses btf_decl_tag attributes to describe the expected test