On Tue, Aug 13, 2019 at 10:41:54AM -0700, Jonathan Lemon wrote:
On 13 Aug 2019, at 3:23, Ivan Khoronzhuk wrote:
For arm32 xdp sockets mmap2 is preferred, so use it if it's defined.
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx>
Doesn't this change the application API?
--
Jonathan
From what I know there is no reason to use both, so if __NR_mmap2 is defined
but not __NR_mmap. Despite the fact that it can be defined internally, say
#define __NR_mmap (__NR_SYSCALL_BASE + 90)
and be used anyway, at least arm use 2 definition one is for old abi and one is
for new and names as their numbers are different:
#define __NR_mmap (__NR_SYSCALL_BASE + 90)
#define __NR_mmap2 (__NR_SYSCALL_BASE + 192)
, so they are not interchangeable and if eabi is used then only __NR_mmap2 is
defined if oeabi then __NR_mmap only... But mmap() use only one and can hide
this from user.
In this patch, seems like here is direct access, so I have no declaration for
__NR_mmap and it breaks build. So here several solutions, I can block __NR_mmap
at all or replace it on __NR_mmap2...or define it by hand (for what then?).
I decided to replace on real one.
---
samples/bpf/syscall_nrs.c | 5 +++++
samples/bpf/tracex5_kern.c | 11 +++++++++++
2 files changed, 16 insertions(+)
diff --git a/samples/bpf/syscall_nrs.c b/samples/bpf/syscall_nrs.c
index 516e255cbe8f..2dec94238350 100644
--- a/samples/bpf/syscall_nrs.c
+++ b/samples/bpf/syscall_nrs.c
@@ -9,5 +9,10 @@ void syscall_defines(void)
COMMENT("Linux system call numbers.");
SYSNR(__NR_write);
SYSNR(__NR_read);
+#ifdef __NR_mmap2
+ SYSNR(__NR_mmap2);
+#else
SYSNR(__NR_mmap);
+#endif
+
}
diff --git a/samples/bpf/tracex5_kern.c b/samples/bpf/tracex5_kern.c
index f57f4e1ea1ec..300350ad299a 100644
--- a/samples/bpf/tracex5_kern.c
+++ b/samples/bpf/tracex5_kern.c
@@ -68,12 +68,23 @@ PROG(SYS__NR_read)(struct pt_regs *ctx)
return 0;
}
+#ifdef __NR_mmap2
+PROG(SYS__NR_mmap2)(struct pt_regs *ctx)
+{
+ char fmt[] = "mmap2\n";
+
+ bpf_trace_printk(fmt, sizeof(fmt));
+ return 0;
+}
+#else
PROG(SYS__NR_mmap)(struct pt_regs *ctx)
{
char fmt[] = "mmap\n";
+
bpf_trace_printk(fmt, sizeof(fmt));
return 0;
}
+#endif
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;
--
2.17.1
--
Regards,
Ivan Khoronzhuk
