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
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