diff mbox series

[RFC,bpf-next,v2,3/4] bpf, x64: Load tail_call_cnt pointer

Message ID 20231011152725.95895-4-hffilwlqm@gmail.com (mailing list archive)
State RFC
Delegated to: BPF
Headers show
Series bpf, x64: Fix tailcall hierarchy | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR success PR summary
bpf/vmtest-bpf-next-VM_Test-0 success Logs for ShellCheck
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 9 this patch: 9
netdev/cc_maintainers warning 17 maintainers not CCed: song@kernel.org mingo@redhat.com netdev@vger.kernel.org yonghong.song@linux.dev jolsa@kernel.org tglx@linutronix.de x86@kernel.org kpsingh@kernel.org dsahern@kernel.org john.fastabend@gmail.com bp@alien8.de davem@davemloft.net dave.hansen@linux.intel.com sdf@google.com hpa@zytor.com haoluo@google.com martin.lau@linux.dev
netdev/build_clang success Errors and warnings before: 1364 this patch: 1364
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1365 this patch: 1365
netdev/checkpatch warning WARNING: line length of 83 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Leon Hwang Oct. 11, 2023, 3:27 p.m. UTC 
Rename RESTORE_TAIL_CALL_CNT() to LOAD_TAIL_CALL_CNT_PTR().

With previous commit, rax is used to propagate tail_call_cnt pointer
instead of tail_call_cnt. So, LOAD_TAIL_CALL_CNT_PTR() is better.

Signed-off-by: Leon Hwang <hffilwlqm@gmail.com>
---
 arch/x86/net/bpf_jit_comp.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

Comments

Maciej Fijalkowski Dec. 11, 2023, 6:03 p.m. UTC | #1 
On Wed, Oct 11, 2023 at 11:27:24PM +0800, Leon Hwang wrote:
> Rename RESTORE_TAIL_CALL_CNT() to LOAD_TAIL_CALL_CNT_PTR().
> 
> With previous commit, rax is used to propagate tail_call_cnt pointer
> instead of tail_call_cnt. So, LOAD_TAIL_CALL_CNT_PTR() is better.
> 
> Signed-off-by: Leon Hwang <hffilwlqm@gmail.com>

IMHO this is out of the scope for this set. We are going to target the bpf
tree and this patch can be send to bpf-next in the future.

> ---
>  arch/x86/net/bpf_jit_comp.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
Leon Hwang Dec. 13, 2023, 2:49 a.m. UTC | #2 
On 12/12/23 02:03, Maciej Fijalkowski wrote:
> On Wed, Oct 11, 2023 at 11:27:24PM +0800, Leon Hwang wrote:
>> Rename RESTORE_TAIL_CALL_CNT() to LOAD_TAIL_CALL_CNT_PTR().
>>
>> With previous commit, rax is used to propagate tail_call_cnt pointer
>> instead of tail_call_cnt. So, LOAD_TAIL_CALL_CNT_PTR() is better.
>>
>> Signed-off-by: Leon Hwang <hffilwlqm@gmail.com>
> 
> IMHO this is out of the scope for this set. We are going to target the bpf
> tree and this patch can be send to bpf-next in the future.
> 

LGTM.

Thanks,
Leon

>> ---
>>  arch/x86/net/bpf_jit_comp.c | 18 +++++++++---------
>>  1 file changed, 9 insertions(+), 9 deletions(-)
>>
diff mbox series

Patch

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 36631129cc800..73da9a2125589 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1077,7 +1077,7 @@  static void emit_shiftx(u8 **pprog, u32 dst_reg, u8 src_reg, bool is64, u8 op)
 #define INSN_SZ_DIFF (((addrs[i] - addrs[i - 1]) - (prog - temp)))
 
 /* mov rax, qword ptr [rbp - rounded_stack_depth - 8] */
-#define RESTORE_TAIL_CALL_CNT(stack)				\
+#define LOAD_TAIL_CALL_CNT_PTR(stack)				\
 	EMIT3_off32(0x48, 0x8B, 0x85, -round_up(stack, 8) - 8)
 
 static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image,
@@ -1697,7 +1697,7 @@  st:			if (is_imm8(insn->off))
 
 			func = (u8 *) __bpf_call_base + imm32;
 			if (tail_call_reachable) {
-				RESTORE_TAIL_CALL_CNT(bpf_prog->aux->stack_depth);
+				LOAD_TAIL_CALL_CNT_PTR(bpf_prog->aux->stack_depth);
 				if (!imm32)
 					return -EINVAL;
 				offs = 7 + x86_call_depth_emit_accounting(&prog, func);
@@ -2479,7 +2479,7 @@  int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
 	 *                     [ ...        ]
 	 *                     [ stack_arg2 ]
 	 * RBP - arg_stack_off [ stack_arg1 ]
-	 * RSP                 [ tail_call_cnt ] BPF_TRAMP_F_TAIL_CALL_CTX
+	 * RSP                 [ tail_call_cnt_ptr ] BPF_TRAMP_F_TAIL_CALL_CTX
 	 */
 
 	/* room for return value of orig_call or fentry prog */
@@ -2599,10 +2599,10 @@  int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
 		save_args(m, &prog, arg_stack_off, true);
 
 		if (flags & BPF_TRAMP_F_TAIL_CALL_CTX)
-			/* Before calling the original function, restore the
-			 * tail_call_cnt from stack to rax.
+			/* Before calling the original function, load the
+			 * tail_call_cnt_ptr to rax.
 			 */
-			RESTORE_TAIL_CALL_CNT(stack_size);
+			LOAD_TAIL_CALL_CNT_PTR(stack_size);
 
 		if (flags & BPF_TRAMP_F_ORIG_STACK) {
 			emit_ldx(&prog, BPF_DW, BPF_REG_6, BPF_REG_FP, 8);
@@ -2658,10 +2658,10 @@  int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
 			goto cleanup;
 		}
 	} else if (flags & BPF_TRAMP_F_TAIL_CALL_CTX)
-		/* Before running the original function, restore the
-		 * tail_call_cnt from stack to rax.
+		/* Before running the original function, load the
+		 * tail_call_cnt_ptr to rax.
 		 */
-		RESTORE_TAIL_CALL_CNT(stack_size);
+		LOAD_TAIL_CALL_CNT_PTR(stack_size);
 
 	/* restore return value of orig_call or fentry prog back into RAX */
 	if (save_ret)