This is a note to let you know that I've just added the patch titled
bpf, x86: save/restore regs with BPF_DW size
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-x86-save-restore-regs-with-bpf_dw-size.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 76e480d3452e8b6d771d697f41b5442e8fce702f
Author: Menglong Dong <imagedong@xxxxxxxxxxx>
Date: Thu Jul 13 12:07:36 2023 +0800
bpf, x86: save/restore regs with BPF_DW size
[ Upstream commit 02a6dfa8ff43efb1c989f87a4d862aedf436088a ]
As we already reserve 8 byte in the stack for each reg, it is ok to
store/restore the regs in BPF_DW size. This will make the code in
save_regs()/restore_regs() simpler.
Signed-off-by: Menglong Dong <imagedong@xxxxxxxxxxx>
Acked-by: Yonghong Song <yhs@xxxxxx>
Link: https://lore.kernel.org/r/20230713040738.1789742-2-imagedong@xxxxxxxxxxx
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Stable-dep-of: 2b5dcb31a19a ("bpf, x64: Fix tailcall infinite loop")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 438adb695daab..fcbd3b7123a47 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1860,57 +1860,34 @@ st: if (is_imm8(insn->off))
static void save_regs(const struct btf_func_model *m, u8 **prog, int nr_regs,
int stack_size)
{
- int i, j, arg_size;
- bool next_same_struct = false;
+ int i;
/* Store function arguments to stack.
* For a function that accepts two pointers the sequence will be:
* mov QWORD PTR [rbp-0x10],rdi
* mov QWORD PTR [rbp-0x8],rsi
*/
- for (i = 0, j = 0; i < min(nr_regs, 6); i++) {
- /* The arg_size is at most 16 bytes, enforced by the verifier. */
- arg_size = m->arg_size[j];
- if (arg_size > 8) {
- arg_size = 8;
- next_same_struct = !next_same_struct;
- }
-
- emit_stx(prog, bytes_to_bpf_size(arg_size),
- BPF_REG_FP,
+ for (i = 0; i < min(nr_regs, 6); i++)
+ emit_stx(prog, BPF_DW, BPF_REG_FP,
i == 5 ? X86_REG_R9 : BPF_REG_1 + i,
-(stack_size - i * 8));
-
- j = next_same_struct ? j : j + 1;
- }
}
static void restore_regs(const struct btf_func_model *m, u8 **prog, int nr_regs,
int stack_size)
{
- int i, j, arg_size;
- bool next_same_struct = false;
+ int i;
/* Restore function arguments from stack.
* For a function that accepts two pointers the sequence will be:
* EMIT4(0x48, 0x8B, 0x7D, 0xF0); mov rdi,QWORD PTR [rbp-0x10]
* EMIT4(0x48, 0x8B, 0x75, 0xF8); mov rsi,QWORD PTR [rbp-0x8]
*/
- for (i = 0, j = 0; i < min(nr_regs, 6); i++) {
- /* The arg_size is at most 16 bytes, enforced by the verifier. */
- arg_size = m->arg_size[j];
- if (arg_size > 8) {
- arg_size = 8;
- next_same_struct = !next_same_struct;
- }
-
- emit_ldx(prog, bytes_to_bpf_size(arg_size),
+ for (i = 0; i < min(nr_regs, 6); i++)
+ emit_ldx(prog, BPF_DW,
i == 5 ? X86_REG_R9 : BPF_REG_1 + i,
BPF_REG_FP,
-(stack_size - i * 8));
-
- j = next_same_struct ? j : j + 1;
- }
}
static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
