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s390/bpf: Centralize frame offset calculations

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The calculation of the distance from %r15 to the caller-allocated
portion of the stack frame is copy-pasted into multiple places in the
JIT code.

Move it to bpf_jit_prog() and save the result into bpf_jit::frame_off,
so that the other parts of the JIT can use it.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20250624121501.50536-2-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Ilya Leoshkevich 2025-06-24 14:04:27 +02:00 committed by Alexei Starovoitov
parent c4b1be928e
commit b2268d550d
1 changed files with 26 additions and 30 deletions
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56
arch/s390/net/bpf_jit_comp.c
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@ -54,6 +54,7 @@ struct bpf_jit {
int prologue_plt; /* Start of prologue hotpatch PLT */
int kern_arena; /* Pool offset of kernel arena address */
u64 user_arena; /* User arena address */
u32 frame_off; /* Offset of frame from %r15 */
};
#define SEEN_MEM BIT(0) /* use mem[] for temporary storage */
@ -443,12 +444,9 @@ static void save_regs(struct bpf_jit *jit, u32 rs, u32 re)
/*
* Restore registers from "rs" (register start) to "re" (register end) on stack
*/
static void restore_regs(struct bpf_jit *jit, u32 rs, u32 re, u32 stack_depth)
static void restore_regs(struct bpf_jit *jit, u32 rs, u32 re)
{
u32 off = STK_OFF_R6 + (rs - 6) * 8;
if (jit->seen & SEEN_STACK)
off += STK_OFF + stack_depth;
u32 off = jit->frame_off + STK_OFF_R6 + (rs - 6) * 8;
if (rs == re)
/* lg %rs,off(%r15) */
@ -492,8 +490,7 @@ static int get_end(u16 seen_regs, int start)
* Save and restore clobbered registers (6-15) on stack.
* We save/restore registers in chunks with gap >= 2 registers.
*/
static void save_restore_regs(struct bpf_jit *jit, int op, u32 stack_depth,
u16 extra_regs)
static void save_restore_regs(struct bpf_jit *jit, int op, u16 extra_regs)
{
u16 seen_regs = jit->seen_regs | extra_regs;
const int last = 15, save_restore_size = 6;
@ -516,7 +513,7 @@ static void save_restore_regs(struct bpf_jit *jit, int op, u32 stack_depth,
if (op == REGS_SAVE)
save_regs(jit, rs, re);
else
restore_regs(jit, rs, re, stack_depth);
restore_regs(jit, rs, re);
re++;
} while (re <= last);
}
@ -575,8 +572,7 @@ static void bpf_jit_plt(struct bpf_plt *plt, void *ret, void *target)
* Save registers and create stack frame if necessary.
* See stack frame layout description in "bpf_jit.h"!
*/
static void bpf_jit_prologue(struct bpf_jit *jit, struct bpf_prog *fp,
u32 stack_depth)
static void bpf_jit_prologue(struct bpf_jit *jit, struct bpf_prog *fp)
{
/* No-op for hotpatching */
/* brcl 0,prologue_plt */
@ -609,7 +605,7 @@ static void bpf_jit_prologue(struct bpf_jit *jit, struct bpf_prog *fp,
jit->seen_regs |= NVREGS;
} else {
/* Save registers */
save_restore_regs(jit, REGS_SAVE, stack_depth,
save_restore_regs(jit, REGS_SAVE,
fp->aux->exception_boundary ? NVREGS : 0);
}
/* Setup literal pool */
@ -631,8 +627,8 @@ static void bpf_jit_prologue(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT4(0xb9040000, REG_W1, REG_15);
/* la %bfp,STK_160_UNUSED(%r15) (BPF frame pointer) */
EMIT4_DISP(0x41000000, BPF_REG_FP, REG_15, STK_160_UNUSED);
/* aghi %r15,-STK_OFF */
EMIT4_IMM(0xa70b0000, REG_15, -(STK_OFF + stack_depth));
/* aghi %r15,-frame_off */
EMIT4_IMM(0xa70b0000, REG_15, -jit->frame_off);
/* stg %w1,152(%r15) (backchain) */
EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0,
REG_15, 152);
@ -669,13 +665,13 @@ static void call_r1(struct bpf_jit *jit)
/*
* Function epilogue
*/
static void bpf_jit_epilogue(struct bpf_jit *jit, u32 stack_depth)
static void bpf_jit_epilogue(struct bpf_jit *jit)
{
jit->exit_ip = jit->prg;
/* Load exit code: lgr %r2,%b0 */
EMIT4(0xb9040000, REG_2, BPF_REG_0);
/* Restore registers */
save_restore_regs(jit, REGS_RESTORE, stack_depth, 0);
save_restore_regs(jit, REGS_RESTORE, 0);
EMIT_JUMP_REG(14);
jit->prg = ALIGN(jit->prg, 8);
@ -857,7 +853,7 @@ static int sign_extend(struct bpf_jit *jit, int r, u8 size, u8 flags)
* stack space for the large switch statement.
*/
static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
int i, bool extra_pass, u32 stack_depth)
int i, bool extra_pass)
{
struct bpf_insn *insn = &fp->insnsi[i];
s32 branch_oc_off = insn->off;
@ -1778,9 +1774,9 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
* Note 2: We assume that the verifier does not let us call the
* main program, which clears the tail call counter on entry.
*/
/* mvc STK_OFF_TCCNT(4,%r15),N(%r15) */
/* mvc STK_OFF_TCCNT(4,%r15),frame_off+STK_OFF_TCCNT(%r15) */
_EMIT6(0xd203f000 | STK_OFF_TCCNT,
0xf000 | (STK_OFF_TCCNT + STK_OFF + stack_depth));
0xf000 | (jit->frame_off + STK_OFF_TCCNT));
/* Sign-extend the kfunc arguments. */
if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
@ -1831,10 +1827,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
* goto out;
*/
if (jit->seen & SEEN_STACK)
off = STK_OFF_TCCNT + STK_OFF + stack_depth;
else
off = STK_OFF_TCCNT;
off = jit->frame_off + STK_OFF_TCCNT;
/* lhi %w0,1 */
EMIT4_IMM(0xa7080000, REG_W0, 1);
/* laal %w1,%w0,off(%r15) */
@ -1864,7 +1857,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
/*
* Restore registers before calling function
*/
save_restore_regs(jit, REGS_RESTORE, stack_depth, 0);
save_restore_regs(jit, REGS_RESTORE, 0);
/*
* goto *(prog->bpf_func + tail_call_start);
@ -2157,7 +2150,7 @@ static int bpf_set_addr(struct bpf_jit *jit, int i)
* Compile eBPF program into s390x code
*/
static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp,
bool extra_pass, u32 stack_depth)
bool extra_pass)
{
int i, insn_count, lit32_size, lit64_size;
u64 kern_arena;
@ -2166,24 +2159,28 @@ static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp,
jit->lit64 = jit->lit64_start;
jit->prg = 0;
jit->excnt = 0;
if (is_first_pass(jit) || (jit->seen & SEEN_STACK))
jit->frame_off = STK_OFF + round_up(fp->aux->stack_depth, 8);
else
jit->frame_off = 0;
kern_arena = bpf_arena_get_kern_vm_start(fp->aux->arena);
if (kern_arena)
jit->kern_arena = _EMIT_CONST_U64(kern_arena);
jit->user_arena = bpf_arena_get_user_vm_start(fp->aux->arena);
bpf_jit_prologue(jit, fp, stack_depth);
bpf_jit_prologue(jit, fp);
if (bpf_set_addr(jit, 0) < 0)
return -1;
for (i = 0; i < fp->len; i += insn_count) {
insn_count = bpf_jit_insn(jit, fp, i, extra_pass, stack_depth);
insn_count = bpf_jit_insn(jit, fp, i, extra_pass);
if (insn_count < 0)
return -1;
/* Next instruction address */
if (bpf_set_addr(jit, i + insn_count) < 0)
return -1;
}
bpf_jit_epilogue(jit, stack_depth);
bpf_jit_epilogue(jit);
lit32_size = jit->lit32 - jit->lit32_start;
lit64_size = jit->lit64 - jit->lit64_start;
@ -2259,7 +2256,6 @@ static struct bpf_binary_header *bpf_jit_alloc(struct bpf_jit *jit,
*/
struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
{
u32 stack_depth = round_up(fp->aux->stack_depth, 8);
struct bpf_prog *tmp, *orig_fp = fp;
struct bpf_binary_header *header;
struct s390_jit_data *jit_data;
@ -2312,7 +2308,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
* - 3: Calculate program size and addrs array
*/
for (pass = 1; pass <= 3; pass++) {
if (bpf_jit_prog(&jit, fp, extra_pass, stack_depth)) {
if (bpf_jit_prog(&jit, fp, extra_pass)) {
fp = orig_fp;
goto free_addrs;
}
@ -2326,7 +2322,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
goto free_addrs;
}
skip_init_ctx:
if (bpf_jit_prog(&jit, fp, extra_pass, stack_depth)) {
if (bpf_jit_prog(&jit, fp, extra_pass)) {
bpf_jit_binary_free(header);
fp = orig_fp;
goto free_addrs;