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x86, bpf: Use bpf_prog_pack for bpf trampoline
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There are three major changes here:

1. Add arch_[alloc|free]_bpf_trampoline based on bpf_prog_pack;
2. Let arch_prepare_bpf_trampoline handle ROX input image, this requires
   arch_prepare_bpf_trampoline allocating a temporary RW buffer;
3. Update __arch_prepare_bpf_trampoline() to handle a RW buffer (rw_image)
   and a ROX buffer (image). This part is similar to the image/rw_image
   logic in bpf_int_jit_compile().

Signed-off-by: Song Liu <[email protected]>
Acked-by: Ilya Leoshkevich <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>
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@liu-song-6
liu-song-6 authored and Alexei Starovoitov committed Dec 7, 2023
1 parent 26ef208 commit 3ba026f
Showing 1 changed file with 72 additions and 26 deletions.
98 changes: 72 additions & 26 deletions arch/x86/net/bpf_jit_comp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2198,7 +2198,8 @@ static void restore_regs(const struct btf_func_model *m, u8 **prog,

static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
struct bpf_tramp_link *l, int stack_size,
int run_ctx_off, bool save_ret)
int run_ctx_off, bool save_ret,
void *image, void *rw_image)
{
u8 *prog = *pprog;
u8 *jmp_insn;
Expand Down Expand Up @@ -2226,7 +2227,7 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
else
EMIT4(0x48, 0x8D, 0x75, -run_ctx_off);

if (emit_rsb_call(&prog, bpf_trampoline_enter(p), prog))
if (emit_rsb_call(&prog, bpf_trampoline_enter(p), image + (prog - (u8 *)rw_image)))
return -EINVAL;
/* remember prog start time returned by __bpf_prog_enter */
emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0);
Expand All @@ -2250,7 +2251,7 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
(long) p->insnsi >> 32,
(u32) (long) p->insnsi);
/* call JITed bpf program or interpreter */
if (emit_rsb_call(&prog, p->bpf_func, prog))
if (emit_rsb_call(&prog, p->bpf_func, image + (prog - (u8 *)rw_image)))
return -EINVAL;

/*
Expand All @@ -2277,7 +2278,7 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
EMIT3_off32(0x48, 0x8D, 0x95, -run_ctx_off);
else
EMIT4(0x48, 0x8D, 0x55, -run_ctx_off);
if (emit_rsb_call(&prog, bpf_trampoline_exit(p), prog))
if (emit_rsb_call(&prog, bpf_trampoline_exit(p), image + (prog - (u8 *)rw_image)))
return -EINVAL;

*pprog = prog;
Expand Down Expand Up @@ -2312,14 +2313,15 @@ static int emit_cond_near_jump(u8 **pprog, void *func, void *ip, u8 jmp_cond)

static int invoke_bpf(const struct btf_func_model *m, u8 **pprog,
struct bpf_tramp_links *tl, int stack_size,
int run_ctx_off, bool save_ret)
int run_ctx_off, bool save_ret,
void *image, void *rw_image)
{
int i;
u8 *prog = *pprog;

for (i = 0; i < tl->nr_links; i++) {
if (invoke_bpf_prog(m, &prog, tl->links[i], stack_size,
run_ctx_off, save_ret))
run_ctx_off, save_ret, image, rw_image))
return -EINVAL;
}
*pprog = prog;
Expand All @@ -2328,7 +2330,8 @@ static int invoke_bpf(const struct btf_func_model *m, u8 **pprog,

static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
struct bpf_tramp_links *tl, int stack_size,
int run_ctx_off, u8 **branches)
int run_ctx_off, u8 **branches,
void *image, void *rw_image)
{
u8 *prog = *pprog;
int i;
Expand All @@ -2339,7 +2342,8 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
emit_mov_imm32(&prog, false, BPF_REG_0, 0);
emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
for (i = 0; i < tl->nr_links; i++) {
if (invoke_bpf_prog(m, &prog, tl->links[i], stack_size, run_ctx_off, true))
if (invoke_bpf_prog(m, &prog, tl->links[i], stack_size, run_ctx_off, true,
image, rw_image))
return -EINVAL;

/* mod_ret prog stored return value into [rbp - 8]. Emit:
Expand Down Expand Up @@ -2422,7 +2426,8 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
* add rsp, 8 // skip eth_type_trans's frame
* ret // return to its caller
*/
static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end,
static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_image,
void *rw_image_end, void *image,
const struct btf_func_model *m, u32 flags,
struct bpf_tramp_links *tlinks,
void *func_addr)
Expand Down Expand Up @@ -2521,7 +2526,7 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image
orig_call += X86_PATCH_SIZE;
}

prog = image;
prog = rw_image;

EMIT_ENDBR();
/*
Expand Down Expand Up @@ -2563,15 +2568,16 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image
if (flags & BPF_TRAMP_F_CALL_ORIG) {
/* arg1: mov rdi, im */
emit_mov_imm64(&prog, BPF_REG_1, (long) im >> 32, (u32) (long) im);
if (emit_rsb_call(&prog, __bpf_tramp_enter, prog)) {
if (emit_rsb_call(&prog, __bpf_tramp_enter,
image + (prog - (u8 *)rw_image))) {
ret = -EINVAL;
goto cleanup;
}
}

if (fentry->nr_links)
if (invoke_bpf(m, &prog, fentry, regs_off, run_ctx_off,
flags & BPF_TRAMP_F_RET_FENTRY_RET))
flags & BPF_TRAMP_F_RET_FENTRY_RET, image, rw_image))
return -EINVAL;

if (fmod_ret->nr_links) {
Expand All @@ -2581,7 +2587,7 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image
return -ENOMEM;

if (invoke_bpf_mod_ret(m, &prog, fmod_ret, regs_off,
run_ctx_off, branches)) {
run_ctx_off, branches, image, rw_image)) {
ret = -EINVAL;
goto cleanup;
}
Expand All @@ -2602,14 +2608,14 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image
EMIT2(0xff, 0xd3); /* call *rbx */
} else {
/* call original function */
if (emit_rsb_call(&prog, orig_call, prog)) {
if (emit_rsb_call(&prog, orig_call, image + (prog - (u8 *)rw_image))) {
ret = -EINVAL;
goto cleanup;
}
}
/* remember return value in a stack for bpf prog to access */
emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
im->ip_after_call = prog;
im->ip_after_call = image + (prog - (u8 *)rw_image);
memcpy(prog, x86_nops[5], X86_PATCH_SIZE);
prog += X86_PATCH_SIZE;
}
Expand All @@ -2625,12 +2631,13 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image
* aligned address of do_fexit.
*/
for (i = 0; i < fmod_ret->nr_links; i++)
emit_cond_near_jump(&branches[i], prog, branches[i],
X86_JNE);
emit_cond_near_jump(&branches[i], image + (prog - (u8 *)rw_image),
image + (branches[i] - (u8 *)rw_image), X86_JNE);
}

if (fexit->nr_links)
if (invoke_bpf(m, &prog, fexit, regs_off, run_ctx_off, false)) {
if (invoke_bpf(m, &prog, fexit, regs_off, run_ctx_off,
false, image, rw_image)) {
ret = -EINVAL;
goto cleanup;
}
Expand All @@ -2643,10 +2650,10 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image
* restored to R0.
*/
if (flags & BPF_TRAMP_F_CALL_ORIG) {
im->ip_epilogue = prog;
im->ip_epilogue = image + (prog - (u8 *)rw_image);
/* arg1: mov rdi, im */
emit_mov_imm64(&prog, BPF_REG_1, (long) im >> 32, (u32) (long) im);
if (emit_rsb_call(&prog, __bpf_tramp_exit, prog)) {
if (emit_rsb_call(&prog, __bpf_tramp_exit, image + (prog - (u8 *)rw_image))) {
ret = -EINVAL;
goto cleanup;
}
Expand All @@ -2665,25 +2672,64 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image
if (flags & BPF_TRAMP_F_SKIP_FRAME)
/* skip our return address and return to parent */
EMIT4(0x48, 0x83, 0xC4, 8); /* add rsp, 8 */
emit_return(&prog, prog);
emit_return(&prog, image + (prog - (u8 *)rw_image));
/* Make sure the trampoline generation logic doesn't overflow */
if (WARN_ON_ONCE(prog > (u8 *)image_end - BPF_INSN_SAFETY)) {
if (WARN_ON_ONCE(prog > (u8 *)rw_image_end - BPF_INSN_SAFETY)) {
ret = -EFAULT;
goto cleanup;
}
ret = prog - (u8 *)image + BPF_INSN_SAFETY;
ret = prog - (u8 *)rw_image + BPF_INSN_SAFETY;

cleanup:
kfree(branches);
return ret;
}

void *arch_alloc_bpf_trampoline(unsigned int size)
{
return bpf_prog_pack_alloc(size, jit_fill_hole);
}

void arch_free_bpf_trampoline(void *image, unsigned int size)
{
bpf_prog_pack_free(image, size);
}

void arch_protect_bpf_trampoline(void *image, unsigned int size)
{
}

void arch_unprotect_bpf_trampoline(void *image, unsigned int size)
{
}

int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end,
const struct btf_func_model *m, u32 flags,
struct bpf_tramp_links *tlinks,
void *func_addr)
{
return __arch_prepare_bpf_trampoline(im, image, image_end, m, flags, tlinks, func_addr);
void *rw_image, *tmp;
int ret;
u32 size = image_end - image;

/* rw_image doesn't need to be in module memory range, so we can
* use kvmalloc.
*/
rw_image = kvmalloc(size, GFP_KERNEL);
if (!rw_image)
return -ENOMEM;

ret = __arch_prepare_bpf_trampoline(im, rw_image, rw_image + size, image, m,
flags, tlinks, func_addr);
if (ret < 0)
goto out;

tmp = bpf_arch_text_copy(image, rw_image, size);
if (IS_ERR(tmp))
ret = PTR_ERR(tmp);
out:
kvfree(rw_image);
return ret;
}

int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags,
Expand All @@ -2704,8 +2750,8 @@ int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags,
if (!image)
return -ENOMEM;

ret = __arch_prepare_bpf_trampoline(&im, image, image + PAGE_SIZE, m, flags,
tlinks, func_addr);
ret = __arch_prepare_bpf_trampoline(&im, image, image + PAGE_SIZE, image,
m, flags, tlinks, func_addr);
bpf_jit_free_exec(image);
return ret;
}
Expand Down

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