linux-kernel - Re: [PATCH V1 10/19] perf tools: Create maps for x86 PTI entry trampolines

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Date:   Wed, 16 May 2018 13:06:56 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...ux.intel.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>, linux-kernel@...r.kernel.org,
        x86@...nel.org
Subject: Re: [PATCH V1 10/19] perf tools: Create maps for x86 PTI entry
 trampolines

On Tue, May 15, 2018 at 03:43:24PM +0300, Adrian Hunter wrote:

SNIP

> +int machine__create_extra_kernel_map(struct machine *machine,
> +				     struct dso *kernel,
> +				     struct extra_kernel_map *xm)
>  {
>  	struct kmap *kmap;
>  	struct map *map;
> @@ -923,9 +915,33 @@ static u64 find_entry_trampoline(struct dso *dso)
>  int machine__map_x86_64_entry_trampolines(struct machine *machine,
>  					  struct dso *kernel)
>  {
> -	u64 pgoff = find_entry_trampoline(kernel);
> +	struct map_groups *kmaps = &machine->kmaps;
> +	struct maps *maps = &kmaps->maps;
>  	int nr_cpus_avail = 0, cpu;
> +	bool found = false;
> +	struct map *map;
> +	u64 pgoff;
> +
> +	/*
> +	 * In the vmlinux case, pgoff is a virtual address which must now be
> +	 * mapped to a vmlinux offset.
> +	 */
> +	for (map = maps__first(maps); map; map = map__next(map)) {
> +		struct kmap *kmap = __map__kmap(map);
> +		struct map *dest_map;
> +
> +		if (!kmap || !is_entry_trampoline(kmap->name))
> +			continue;
> +
> +		dest_map = map_groups__find(kmaps, map->pgoff);
> +		if (dest_map != map)
> +			map->pgoff = dest_map->map_ip(dest_map, map->pgoff);
> +		found = true;

hum, could you please explain/comment on above? the purpose of pgoff for these maps

all the trampoline maps seems to have the same pgoff at the end..

0 0x158 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe0000006000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x1b0 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe0000032000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x208 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe000005e000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x260 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe000008a000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x2b8 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe00000b6000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x310 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe00000e2000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x368 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe000010e000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x3c0 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe000013a000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x418 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe0000166000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x470 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe0000192000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x4c8 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe00001be000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x520 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe00001ea000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x578 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe0000216000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x5d0 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe0000242000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x628 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe000026e000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x680 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe000029a000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x6d8 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe00002c6000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x730 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe00002f2000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x788 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe000031e000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x7e0 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe000034a000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x838 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe0000376000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x890 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe00003a2000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x8e8 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe00003ce000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline
0 0x940 [0x58]: PERF_RECORD_MMAP -1/0: [0xfffffe00003fa000(0x1000) @ 0xffffffff8fc02000]: x __entry_SYSCALL_64_trampoline

thanks,
jirka