* [PATCH V4 0/3] perf tools and x86 PTI entry trampolines @ 2018-06-06 12:54 Adrian Hunter 2018-06-06 12:54 ` [PATCH V4 1/3] kallsyms: Simplify update_iter_mod() Adrian Hunter ` (2 more replies) 0 siblings, 3 replies; 17+ messages in thread From: Adrian Hunter @ 2018-06-06 12:54 UTC (permalink / raw) To: Thomas Gleixner, Arnaldo Carvalho de Melo Cc: Ingo Molnar, Peter Zijlstra, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86 Hi Here is V4 of patches to support x86 PTI entry trampolines in perf tools. Patches also here: http://git.infradead.org/users/ahunter/linux-perf.git/shortlog/refs/heads/perf-tools-kpti-v4 git://git.infradead.org/users/ahunter/linux-perf.git perf-tools-kpti-v4 V3 patches also here: http://git.infradead.org/users/ahunter/linux-perf.git/shortlog/refs/heads/perf-tools-kpti-v3 git://git.infradead.org/users/ahunter/linux-perf.git perf-tools-kpti-v3 V2 patches also here: http://git.infradead.org/users/ahunter/linux-perf.git/shortlog/refs/heads/perf-tools-kpti-v2 git://git.infradead.org/users/ahunter/linux-perf.git perf-tools-kpti-v2 V1 patches also here: http://git.infradead.org/users/ahunter/linux-perf.git/shortlog/refs/heads/perf-tools-kpti-v1 git://git.infradead.org/users/ahunter/linux-perf.git perf-tools-kpti-v1 Changes Since V3: kallsyms: Simplify update_iter_mod() Added comment Added Andi's Ack kallsyms, x86: Export addresses of PTI entry trampolines Expanded commit message Used for_each_possible_cpu() Added Andi's Ack even though logic changed slightly x86: Add entry trampolines to kcore Re-based Added Andi's Ack perf tools: Add machine__nr_cpus_avail() perf tools: Workaround missing maps for x86 PTI entry trampolines perf tools: Fix map_groups__split_kallsyms() for entry trampoline symbols perf tools: Allow for extra kernel maps perf tools: Create maps for x86 PTI entry trampolines perf tools: Synthesize and process mmap events for x86 PTI entry trampolines perf buildid-cache: kcore_copy: Keep phdr data in a list perf buildid-cache: kcore_copy: Keep a count of phdrs perf buildid-cache: kcore_copy: Calculate offset from phnum perf buildid-cache: kcore_copy: Layout sections perf buildid-cache: kcore_copy: Iterate phdrs perf buildid-cache: kcore_copy: Get rid of kernel_map perf buildid-cache: kcore_copy: Copy x86 PTI entry trampoline sections perf buildid-cache: kcore_copy: Amend the offset of sections that remap kernel text Dropped because they have been applied Changes Since V2: x86: Add entry trampolines to kcore x86: kcore: Give entry trampolines all the same offset in kcore Combined into a single patch Added comment Expand commit message perf tools: Add machine__is() to identify machine arch Dropped because it has been applied perf tools: Fix kernel_start for PTI on x86 Dropped because it has been applied Changes Since V1: perf tools: Use the _stest symbol to identify the kernel map when loading kcore Dropped because it has been applied perf tools: Add machine__is() to identify machine arch New patch perf tools: Fix kernel_start for PTI on x86 Moved definition of machine__is() to a separate patch perf tools: Add machine__nr_cpus_avail() New patch perf tools: Workaround missing maps for x86 PTI entry trampolines Use machine__nr_cpus_avail() perf tools: Create maps for x86 PTI entry trampolines Re-based Changes Since RFC: Change description 'x86_64 KPTI' to 'x86 PTI' Rename 'special' kernel map to 'extra' kernel map etc kallsyms: Simplify update_iter_mod() Expand commit message perf tools: Fix kernel_start for PTI on x86 Amend machine__is() to check if machine is NULL perf tools: Workaround missing maps for x86 PTI entry trampolines Simplify find_entry_trampoline() Add comment before struct extra_kernel_map /* Kernel-space maps for symbols that are outside the main kernel map and module maps */ perf tools: Create maps for x86 PTI entry trampolines Move code presently only used by x86_64 into arch perf tools: Synthesize and process mmap events for x86 PTI entry trampolines Fix spelling 'kernal' -> 'kernel' Rename 'special' kernel map to 'extra' kernel map etc Move code presently only used by x86_64 into arch perf buildid-cache: kcore_copy: Keep phdr data in a list Expand commit message Rename 'list' -> 'node' perf buildid-cache: kcore_copy: Get rid of kernel_map Expand commit message Add phdr_data__new() Rename 'kcore_copy__new_phdr' -> 'kcore_copy_info__addnew' Original Cover email: Perf tools do not know about x86 PTI entry trampolines - see example below. These patches add a workaround, namely "perf tools: Workaround missing maps for x86 PTI entry trampolines", which has the limitation that it hard codes the addresses. Note that the workaround will work for old kernels and old perf.data files, but not for future kernels if the trampoline addresses are ever changed. At present, perf tools uses /proc/kallsyms to construct a memory map for the kernel. Recording such a map in the perf.data file is necessary to deal with kernel relocation and KASLR. While it is reasonable on its own terms, to add symbols for the trampolines to /proc/kallsyms, the motivation here is to have perf tools use them to create memory maps in the same fashion as is done for the kernel text. So the first 2 patches add symbols to /proc/kallsyms for the trampolines: kallsyms: Simplify update_iter_mod() kallsyms, x86: Export addresses of syscall trampolines perf tools have the ability to use /proc/kcore (in conjunction with /proc/kallsyms) as the kernel image. So the next 2 patches add program headers for the trampolines to the kcore ELF: x86: Add entry trampolines to kcore x86: kcore: Give entry trampolines all the same offset in kcore It is worth noting that, with the kcore changes alone, perf tools require no changes to recognise the trampolines when using /proc/kcore. Similarly, if perf tools are used with a matching kallsyms only (by denying access to /proc/kcore or a vmlinux image), then the kallsyms patches are sufficient to recognise the trampolines with no changes needed to the tools. However, in the general case, when using vmlinux or dealing with relocations, perf tools needs memory maps for the trampolines. Because the kernel text map is constructed as a special case, using the same approach for the trampolines means treating them as a special case also, which requires a number of changes to perf tools, and the remaining patches deal with that. Example: make a program that does lots of small syscalls e.g. $ cat uname_x_n.c #include <sys/utsname.h> #include <stdlib.h> int main(int argc, char *argv[]) { long n = argc > 1 ? strtol(argv[1], NULL, 0) : 0; struct utsname u; while (n--) uname(&u); return 0; } and then: sudo perf record uname_x_n 100000 sudo perf report --stdio Before the changes, there are unknown symbols: # Overhead Command Shared Object Symbol # ........ ......... ................ .................................. # 41.91% uname_x_n [kernel.vmlinux] [k] syscall_return_via_sysret 19.22% uname_x_n [kernel.vmlinux] [k] copy_user_enhanced_fast_string 18.70% uname_x_n [unknown] [k] 0xfffffe00000e201b 4.09% uname_x_n libc-2.19.so [.] __GI___uname 3.08% uname_x_n [kernel.vmlinux] [k] do_syscall_64 3.02% uname_x_n [unknown] [k] 0xfffffe00000e2025 2.32% uname_x_n [kernel.vmlinux] [k] down_read 2.27% uname_x_n ld-2.19.so [.] _dl_start 1.97% uname_x_n [unknown] [k] 0xfffffe00000e201e 1.25% uname_x_n [kernel.vmlinux] [k] up_read 1.02% uname_x_n [unknown] [k] 0xfffffe00000e200c 0.99% uname_x_n [kernel.vmlinux] [k] entry_SYSCALL_64 0.16% uname_x_n [kernel.vmlinux] [k] flush_signal_handlers 0.01% perf [kernel.vmlinux] [k] native_sched_clock 0.00% perf [kernel.vmlinux] [k] native_write_msr After the changes there are not: # Overhead Command Shared Object Symbol # ........ ......... ................ .................................. # 41.91% uname_x_n [kernel.vmlinux] [k] syscall_return_via_sysret 24.70% uname_x_n [kernel.vmlinux] [k] entry_SYSCALL_64_trampoline 19.22% uname_x_n [kernel.vmlinux] [k] copy_user_enhanced_fast_string 4.09% uname_x_n libc-2.19.so [.] __GI___uname 3.08% uname_x_n [kernel.vmlinux] [k] do_syscall_64 2.32% uname_x_n [kernel.vmlinux] [k] down_read 2.27% uname_x_n ld-2.19.so [.] _dl_start 1.25% uname_x_n [kernel.vmlinux] [k] up_read 0.99% uname_x_n [kernel.vmlinux] [k] entry_SYSCALL_64 0.16% uname_x_n [kernel.vmlinux] [k] flush_signal_handlers 0.01% perf [kernel.vmlinux] [k] native_sched_clock 0.00% perf [kernel.vmlinux] [k] native_write_msr Adrian Hunter (2): kallsyms: Simplify update_iter_mod() x86: Add entry trampolines to kcore Alexander Shishkin (1): kallsyms, x86: Export addresses of PTI entry trampolines arch/x86/mm/cpu_entry_area.c | 33 ++++++++++++++++++++++++++++ fs/proc/kcore.c | 7 ++++-- include/linux/kcore.h | 13 +++++++++++ kernel/kallsyms.c | 51 ++++++++++++++++++++++++++++++++------------ 4 files changed, 88 insertions(+), 16 deletions(-) Regards Adrian ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH V4 1/3] kallsyms: Simplify update_iter_mod() 2018-06-06 12:54 [PATCH V4 0/3] perf tools and x86 PTI entry trampolines Adrian Hunter @ 2018-06-06 12:54 ` Adrian Hunter 2018-06-06 13:13 ` Peter Zijlstra 2018-08-18 11:59 ` [tip:perf/urgent] " tip-bot for Adrian Hunter 2018-06-06 12:54 ` [PATCH V4 2/3] kallsyms, x86: Export addresses of PTI entry trampolines Adrian Hunter 2018-06-06 12:54 ` [PATCH V4 3/3] x86: Add entry trampolines to kcore Adrian Hunter 2 siblings, 2 replies; 17+ messages in thread From: Adrian Hunter @ 2018-06-06 12:54 UTC (permalink / raw) To: Thomas Gleixner, Arnaldo Carvalho de Melo Cc: Ingo Molnar, Peter Zijlstra, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86 The logic in update_iter_mod() is overcomplicated and gets worse every time another get_ksymbol_* function is added. In preparation for adding another get_ksymbol_* function, simplify logic in update_iter_mod(). Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Acked-by: Andi Kleen <ak@linux.intel.com> --- kernel/kallsyms.c | 25 +++++++++++-------------- 1 file changed, 11 insertions(+), 14 deletions(-) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index a23e21ada81b..aa31aa07f2ef 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -506,27 +506,24 @@ static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) } } +/* + * The end position (last + 1) of each additional kallsyms section is recorded + * in iter->pos_..._end as each section is added, and so can be used to + * determine which get_ksymbol_...() function to call next. + */ static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) { iter->pos = pos; - if (iter->pos_ftrace_mod_end > 0 && - iter->pos_ftrace_mod_end < iter->pos) - return get_ksymbol_bpf(iter); - - if (iter->pos_mod_end > 0 && - iter->pos_mod_end < iter->pos) { - if (!get_ksymbol_ftrace_mod(iter)) - return get_ksymbol_bpf(iter); + if ((!iter->pos_mod_end || iter->pos_mod_end > pos) && + get_ksymbol_mod(iter)) return 1; - } - if (!get_ksymbol_mod(iter)) { - if (!get_ksymbol_ftrace_mod(iter)) - return get_ksymbol_bpf(iter); - } + if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) && + get_ksymbol_ftrace_mod(iter)) + return 1; - return 1; + return get_ksymbol_bpf(iter); } /* Returns false if pos at or past end of file. */ -- 1.9.1 ^ permalink raw reply related [flat|nested] 17+ messages in thread
* Re: [PATCH V4 1/3] kallsyms: Simplify update_iter_mod() 2018-06-06 12:54 ` [PATCH V4 1/3] kallsyms: Simplify update_iter_mod() Adrian Hunter @ 2018-06-06 13:13 ` Peter Zijlstra 2018-06-06 18:37 ` Steven Rostedt 2018-08-18 11:59 ` [tip:perf/urgent] " tip-bot for Adrian Hunter 1 sibling, 1 reply; 17+ messages in thread From: Peter Zijlstra @ 2018-06-06 13:13 UTC (permalink / raw) To: Adrian Hunter Cc: Thomas Gleixner, Arnaldo Carvalho de Melo, Ingo Molnar, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86, rostedt, daniel On Wed, Jun 06, 2018 at 03:54:09PM +0300, Adrian Hunter wrote: > The logic in update_iter_mod() is overcomplicated and gets worse every time > another get_ksymbol_* function is added. > > In preparation for adding another get_ksymbol_* function, simplify logic in > update_iter_mod(). > > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > Acked-by: Andi Kleen <ak@linux.intel.com> Both Daniel and Steven touched this function last year, let's also Cc them. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > kernel/kallsyms.c | 25 +++++++++++-------------- > 1 file changed, 11 insertions(+), 14 deletions(-) > > diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c > index a23e21ada81b..aa31aa07f2ef 100644 > --- a/kernel/kallsyms.c > +++ b/kernel/kallsyms.c > @@ -506,27 +506,24 @@ static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) > } > } > > +/* > + * The end position (last + 1) of each additional kallsyms section is recorded > + * in iter->pos_..._end as each section is added, and so can be used to > + * determine which get_ksymbol_...() function to call next. > + */ > static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) > { > iter->pos = pos; > > - if (iter->pos_ftrace_mod_end > 0 && > - iter->pos_ftrace_mod_end < iter->pos) > - return get_ksymbol_bpf(iter); > - > - if (iter->pos_mod_end > 0 && > - iter->pos_mod_end < iter->pos) { > - if (!get_ksymbol_ftrace_mod(iter)) > - return get_ksymbol_bpf(iter); > + if ((!iter->pos_mod_end || iter->pos_mod_end > pos) && > + get_ksymbol_mod(iter)) > return 1; > - } > > - if (!get_ksymbol_mod(iter)) { > - if (!get_ksymbol_ftrace_mod(iter)) > - return get_ksymbol_bpf(iter); > - } > + if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) && > + get_ksymbol_ftrace_mod(iter)) > + return 1; > > - return 1; > + return get_ksymbol_bpf(iter); > } > > /* Returns false if pos at or past end of file. */ > -- > 1.9.1 > ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH V4 1/3] kallsyms: Simplify update_iter_mod() 2018-06-06 13:13 ` Peter Zijlstra @ 2018-06-06 18:37 ` Steven Rostedt 2018-06-06 18:59 ` Arnaldo Carvalho de Melo 0 siblings, 1 reply; 17+ messages in thread From: Steven Rostedt @ 2018-06-06 18:37 UTC (permalink / raw) To: Peter Zijlstra Cc: Adrian Hunter, Thomas Gleixner, Arnaldo Carvalho de Melo, Ingo Molnar, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86, daniel On Wed, 6 Jun 2018 15:13:02 +0200 Peter Zijlstra <peterz@infradead.org> wrote: > On Wed, Jun 06, 2018 at 03:54:09PM +0300, Adrian Hunter wrote: > > The logic in update_iter_mod() is overcomplicated and gets worse every time > > another get_ksymbol_* function is added. > > > > In preparation for adding another get_ksymbol_* function, simplify logic in > > update_iter_mod(). > > > > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > > Acked-by: Andi Kleen <ak@linux.intel.com> > > Both Daniel and Steven touched this function last year, let's also Cc > them. Thanks for Ccing me. I tested the patch to make sure my changes still work and they do: Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> -- Steve > > Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH V4 1/3] kallsyms: Simplify update_iter_mod() 2018-06-06 18:37 ` Steven Rostedt @ 2018-06-06 18:59 ` Arnaldo Carvalho de Melo 2018-06-06 19:13 ` Steven Rostedt 0 siblings, 1 reply; 17+ messages in thread From: Arnaldo Carvalho de Melo @ 2018-06-06 18:59 UTC (permalink / raw) To: Steven Rostedt Cc: Peter Zijlstra, Adrian Hunter, Thomas Gleixner, Ingo Molnar, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86, daniel Em Wed, Jun 06, 2018 at 02:37:27PM -0400, Steven Rostedt escreveu: > On Wed, 6 Jun 2018 15:13:02 +0200 > Peter Zijlstra <peterz@infradead.org> wrote: > > > On Wed, Jun 06, 2018 at 03:54:09PM +0300, Adrian Hunter wrote: > > > The logic in update_iter_mod() is overcomplicated and gets worse every time > > > another get_ksymbol_* function is added. > > > > > > In preparation for adding another get_ksymbol_* function, simplify logic in > > > update_iter_mod(). > > > > > > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > > > Acked-by: Andi Kleen <ak@linux.intel.com> > > > > Both Daniel and Steven touched this function last year, let's also Cc > > them. > > Thanks for Ccing me. I tested the patch to make sure my changes still > work and they do: > > Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Since you said you tested the patch, may I replace the Acked-by with the stronger Tested-by? Thanks, - Arnaldo ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH V4 1/3] kallsyms: Simplify update_iter_mod() 2018-06-06 18:59 ` Arnaldo Carvalho de Melo @ 2018-06-06 19:13 ` Steven Rostedt 2018-06-06 19:47 ` Arnaldo Carvalho de Melo 0 siblings, 1 reply; 17+ messages in thread From: Steven Rostedt @ 2018-06-06 19:13 UTC (permalink / raw) To: Arnaldo Carvalho de Melo Cc: Peter Zijlstra, Adrian Hunter, Thomas Gleixner, Ingo Molnar, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86, daniel On Wed, 6 Jun 2018 15:59:14 -0300 Arnaldo Carvalho de Melo <acme@kernel.org> wrote: > Em Wed, Jun 06, 2018 at 02:37:27PM -0400, Steven Rostedt escreveu: > > On Wed, 6 Jun 2018 15:13:02 +0200 > > Peter Zijlstra <peterz@infradead.org> wrote: > > > > > On Wed, Jun 06, 2018 at 03:54:09PM +0300, Adrian Hunter wrote: > > > > The logic in update_iter_mod() is overcomplicated and gets worse every time > > > > another get_ksymbol_* function is added. > > > > > > > > In preparation for adding another get_ksymbol_* function, simplify logic in > > > > update_iter_mod(). > > > > > > > > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > > > > Acked-by: Andi Kleen <ak@linux.intel.com> > > > > > > Both Daniel and Steven touched this function last year, let's also Cc > > > them. > > > > Thanks for Ccing me. I tested the patch to make sure my changes still > > work and they do: > > > > Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> > > Since you said you tested the patch, may I replace the Acked-by with the > stronger Tested-by? Well, I only tested it against the changes I made earlier. I didn't do any other testing, which is why I'm reluctant to say "tested by". Perhaps it can be: Tested-by: (ftrace changes only) Steven Rostedt (VMware) <rostedt@goodmis.org> -- Steve ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH V4 1/3] kallsyms: Simplify update_iter_mod() 2018-06-06 19:13 ` Steven Rostedt @ 2018-06-06 19:47 ` Arnaldo Carvalho de Melo 0 siblings, 0 replies; 17+ messages in thread From: Arnaldo Carvalho de Melo @ 2018-06-06 19:47 UTC (permalink / raw) To: Steven Rostedt Cc: Peter Zijlstra, Adrian Hunter, Thomas Gleixner, Ingo Molnar, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86, daniel Em Wed, Jun 06, 2018 at 03:13:00PM -0400, Steven Rostedt escreveu: > On Wed, 6 Jun 2018 15:59:14 -0300 > Arnaldo Carvalho de Melo <acme@kernel.org> wrote: > > > Em Wed, Jun 06, 2018 at 02:37:27PM -0400, Steven Rostedt escreveu: > > > On Wed, 6 Jun 2018 15:13:02 +0200 > > > Peter Zijlstra <peterz@infradead.org> wrote: > > > > > > > On Wed, Jun 06, 2018 at 03:54:09PM +0300, Adrian Hunter wrote: > > > > > The logic in update_iter_mod() is overcomplicated and gets worse every time > > > > > another get_ksymbol_* function is added. > > > > > > > > > > In preparation for adding another get_ksymbol_* function, simplify logic in > > > > > update_iter_mod(). > > > > > > > > > > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > > > > > Acked-by: Andi Kleen <ak@linux.intel.com> > > > > > > > > Both Daniel and Steven touched this function last year, let's also Cc > > > > them. > > > > > > Thanks for Ccing me. I tested the patch to make sure my changes still > > > work and they do: > > > > > > Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> > > > > Since you said you tested the patch, may I replace the Acked-by with the > > stronger Tested-by? > > Well, I only tested it against the changes I made earlier. I didn't do > any other testing, which is why I'm reluctant to say "tested by". > > Perhaps it can be: > > Tested-by: (ftrace changes only) Steven Rostedt (VMware) <rostedt@goodmis.org> I think that brings more useful information to the log, so should be useful. - Arnaldo ^ permalink raw reply [flat|nested] 17+ messages in thread
* [tip:perf/urgent] kallsyms: Simplify update_iter_mod() 2018-06-06 12:54 ` [PATCH V4 1/3] kallsyms: Simplify update_iter_mod() Adrian Hunter 2018-06-06 13:13 ` Peter Zijlstra @ 2018-08-18 11:59 ` tip-bot for Adrian Hunter 1 sibling, 0 replies; 17+ messages in thread From: tip-bot for Adrian Hunter @ 2018-08-18 11:59 UTC (permalink / raw) To: linux-tip-commits Cc: luto, jolsa, peterz, rostedt, mingo, linux-kernel, dave.hansen, tglx, alexander.shishkin, joro, ak, hpa, acme, adrian.hunter Commit-ID: b96679422007c3fa04625be14977904c27c722eb Gitweb: https://git.kernel.org/tip/b96679422007c3fa04625be14977904c27c722eb Author: Adrian Hunter <adrian.hunter@intel.com> AuthorDate: Wed, 6 Jun 2018 15:54:09 +0300 Committer: Arnaldo Carvalho de Melo <acme@redhat.com> CommitDate: Tue, 14 Aug 2018 19:10:23 -0300 kallsyms: Simplify update_iter_mod() The logic in update_iter_mod() is overcomplicated and gets worse every time another get_ksymbol_* function is added. In preparation for adding another get_ksymbol_* function, simplify logic in update_iter_mod(). Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Tested-by: (ftrace changes only) Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Andi Kleen <ak@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86@kernel.org Link: http://lkml.kernel.org/r/1528289651-4113-2-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> --- kernel/kallsyms.c | 25 +++++++++++-------------- 1 file changed, 11 insertions(+), 14 deletions(-) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index a23e21ada81b..aa31aa07f2ef 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -506,27 +506,24 @@ static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) } } +/* + * The end position (last + 1) of each additional kallsyms section is recorded + * in iter->pos_..._end as each section is added, and so can be used to + * determine which get_ksymbol_...() function to call next. + */ static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) { iter->pos = pos; - if (iter->pos_ftrace_mod_end > 0 && - iter->pos_ftrace_mod_end < iter->pos) - return get_ksymbol_bpf(iter); - - if (iter->pos_mod_end > 0 && - iter->pos_mod_end < iter->pos) { - if (!get_ksymbol_ftrace_mod(iter)) - return get_ksymbol_bpf(iter); + if ((!iter->pos_mod_end || iter->pos_mod_end > pos) && + get_ksymbol_mod(iter)) return 1; - } - if (!get_ksymbol_mod(iter)) { - if (!get_ksymbol_ftrace_mod(iter)) - return get_ksymbol_bpf(iter); - } + if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) && + get_ksymbol_ftrace_mod(iter)) + return 1; - return 1; + return get_ksymbol_bpf(iter); } /* Returns false if pos at or past end of file. */ ^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH V4 2/3] kallsyms, x86: Export addresses of PTI entry trampolines 2018-06-06 12:54 [PATCH V4 0/3] perf tools and x86 PTI entry trampolines Adrian Hunter 2018-06-06 12:54 ` [PATCH V4 1/3] kallsyms: Simplify update_iter_mod() Adrian Hunter @ 2018-06-06 12:54 ` Adrian Hunter 2018-06-06 13:14 ` Peter Zijlstra 2018-08-18 11:59 ` [tip:perf/urgent] " tip-bot for Alexander Shishkin 2018-06-06 12:54 ` [PATCH V4 3/3] x86: Add entry trampolines to kcore Adrian Hunter 2 siblings, 2 replies; 17+ messages in thread From: Adrian Hunter @ 2018-06-06 12:54 UTC (permalink / raw) To: Thomas Gleixner, Arnaldo Carvalho de Melo Cc: Ingo Molnar, Peter Zijlstra, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86 From: Alexander Shishkin <alexander.shishkin@linux.intel.com> Currently, the addresses of PTI entry trampolines are not exported to user space. Kernel profiling tools need these addresses to identify the kernel code, so add a symbol and address for each CPU's PTI entry trampoline. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Acked-by: Andi Kleen <ak@linux.intel.com> --- arch/x86/mm/cpu_entry_area.c | 23 +++++++++++++++++++++++ kernel/kallsyms.c | 28 +++++++++++++++++++++++++++- 2 files changed, 50 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c index b45f5aaefd74..fab49fd5190f 100644 --- a/arch/x86/mm/cpu_entry_area.c +++ b/arch/x86/mm/cpu_entry_area.c @@ -2,6 +2,7 @@ #include <linux/spinlock.h> #include <linux/percpu.h> +#include <linux/kallsyms.h> #include <asm/cpu_entry_area.h> #include <asm/pgtable.h> @@ -150,6 +151,28 @@ static void __init setup_cpu_entry_area(int cpu) percpu_setup_debug_store(cpu); } +#ifdef CONFIG_X86_64 +int arch_get_kallsym(unsigned int symnum, unsigned long *value, char *type, + char *name) +{ + unsigned int cpu, ncpu = 0; + + if (symnum >= num_possible_cpus()) + return -EINVAL; + + for_each_possible_cpu(cpu) { + if (ncpu++ >= symnum) + break; + } + + *value = (unsigned long)&get_cpu_entry_area(cpu)->entry_trampoline; + *type = 't'; + strlcpy(name, "__entry_SYSCALL_64_trampoline", KSYM_NAME_LEN); + + return 0; +} +#endif + static __init void setup_cpu_entry_area_ptes(void) { #ifdef CONFIG_X86_32 diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index aa31aa07f2ef..02a0b01380d8 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -432,6 +432,7 @@ int sprint_backtrace(char *buffer, unsigned long address) /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ struct kallsym_iter { loff_t pos; + loff_t pos_arch_end; loff_t pos_mod_end; loff_t pos_ftrace_mod_end; unsigned long value; @@ -443,9 +444,29 @@ struct kallsym_iter { int show_value; }; +int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value, + char *type, char *name) +{ + return -EINVAL; +} + +static int get_ksymbol_arch(struct kallsym_iter *iter) +{ + int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms, + &iter->value, &iter->type, + iter->name); + + if (ret < 0) { + iter->pos_arch_end = iter->pos; + return 0; + } + + return 1; +} + static int get_ksymbol_mod(struct kallsym_iter *iter) { - int ret = module_get_kallsym(iter->pos - kallsyms_num_syms, + int ret = module_get_kallsym(iter->pos - iter->pos_arch_end, &iter->value, &iter->type, iter->name, iter->module_name, &iter->exported); @@ -501,6 +522,7 @@ static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) iter->nameoff = get_symbol_offset(new_pos); iter->pos = new_pos; if (new_pos == 0) { + iter->pos_arch_end = 0; iter->pos_mod_end = 0; iter->pos_ftrace_mod_end = 0; } @@ -515,6 +537,10 @@ static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) { iter->pos = pos; + if ((!iter->pos_arch_end || iter->pos_arch_end > pos) && + get_ksymbol_arch(iter)) + return 1; + if ((!iter->pos_mod_end || iter->pos_mod_end > pos) && get_ksymbol_mod(iter)) return 1; -- 1.9.1 ^ permalink raw reply related [flat|nested] 17+ messages in thread
* Re: [PATCH V4 2/3] kallsyms, x86: Export addresses of PTI entry trampolines 2018-06-06 12:54 ` [PATCH V4 2/3] kallsyms, x86: Export addresses of PTI entry trampolines Adrian Hunter @ 2018-06-06 13:14 ` Peter Zijlstra 2018-08-18 11:59 ` [tip:perf/urgent] " tip-bot for Alexander Shishkin 1 sibling, 0 replies; 17+ messages in thread From: Peter Zijlstra @ 2018-06-06 13:14 UTC (permalink / raw) To: Adrian Hunter Cc: Thomas Gleixner, Arnaldo Carvalho de Melo, Ingo Molnar, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86 On Wed, Jun 06, 2018 at 03:54:10PM +0300, Adrian Hunter wrote: > From: Alexander Shishkin <alexander.shishkin@linux.intel.com> > > Currently, the addresses of PTI entry trampolines are not exported to user > space. Kernel profiling tools need these addresses to identify the kernel > code, so add a symbol and address for each CPU's PTI entry trampoline. > > Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> > Acked-by: Andi Kleen <ak@linux.intel.com> Thanks for the Changelog, Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> ^ permalink raw reply [flat|nested] 17+ messages in thread
* [tip:perf/urgent] kallsyms, x86: Export addresses of PTI entry trampolines 2018-06-06 12:54 ` [PATCH V4 2/3] kallsyms, x86: Export addresses of PTI entry trampolines Adrian Hunter 2018-06-06 13:14 ` Peter Zijlstra @ 2018-08-18 11:59 ` tip-bot for Alexander Shishkin 1 sibling, 0 replies; 17+ messages in thread From: tip-bot for Alexander Shishkin @ 2018-08-18 11:59 UTC (permalink / raw) To: linux-tip-commits Cc: dave.hansen, peterz, acme, mingo, luto, linux-kernel, alexander.shishkin, joro, ak, hpa, jolsa, tglx Commit-ID: d83212d5dd6761625fe87cc23016bbaa47303271 Gitweb: https://git.kernel.org/tip/d83212d5dd6761625fe87cc23016bbaa47303271 Author: Alexander Shishkin <alexander.shishkin@linux.intel.com> AuthorDate: Wed, 6 Jun 2018 15:54:10 +0300 Committer: Arnaldo Carvalho de Melo <acme@redhat.com> CommitDate: Tue, 14 Aug 2018 19:12:29 -0300 kallsyms, x86: Export addresses of PTI entry trampolines Currently, the addresses of PTI entry trampolines are not exported to user space. Kernel profiling tools need these addresses to identify the kernel code, so add a symbol and address for each CPU's PTI entry trampoline. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Acked-by: Andi Kleen <ak@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86@kernel.org Link: http://lkml.kernel.org/r/1528289651-4113-3-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> --- arch/x86/mm/cpu_entry_area.c | 23 +++++++++++++++++++++++ kernel/kallsyms.c | 28 +++++++++++++++++++++++++++- 2 files changed, 50 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c index b45f5aaefd74..fab49fd5190f 100644 --- a/arch/x86/mm/cpu_entry_area.c +++ b/arch/x86/mm/cpu_entry_area.c @@ -2,6 +2,7 @@ #include <linux/spinlock.h> #include <linux/percpu.h> +#include <linux/kallsyms.h> #include <asm/cpu_entry_area.h> #include <asm/pgtable.h> @@ -150,6 +151,28 @@ static void __init setup_cpu_entry_area(int cpu) percpu_setup_debug_store(cpu); } +#ifdef CONFIG_X86_64 +int arch_get_kallsym(unsigned int symnum, unsigned long *value, char *type, + char *name) +{ + unsigned int cpu, ncpu = 0; + + if (symnum >= num_possible_cpus()) + return -EINVAL; + + for_each_possible_cpu(cpu) { + if (ncpu++ >= symnum) + break; + } + + *value = (unsigned long)&get_cpu_entry_area(cpu)->entry_trampoline; + *type = 't'; + strlcpy(name, "__entry_SYSCALL_64_trampoline", KSYM_NAME_LEN); + + return 0; +} +#endif + static __init void setup_cpu_entry_area_ptes(void) { #ifdef CONFIG_X86_32 diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index aa31aa07f2ef..02a0b01380d8 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -432,6 +432,7 @@ int sprint_backtrace(char *buffer, unsigned long address) /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ struct kallsym_iter { loff_t pos; + loff_t pos_arch_end; loff_t pos_mod_end; loff_t pos_ftrace_mod_end; unsigned long value; @@ -443,9 +444,29 @@ struct kallsym_iter { int show_value; }; +int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value, + char *type, char *name) +{ + return -EINVAL; +} + +static int get_ksymbol_arch(struct kallsym_iter *iter) +{ + int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms, + &iter->value, &iter->type, + iter->name); + + if (ret < 0) { + iter->pos_arch_end = iter->pos; + return 0; + } + + return 1; +} + static int get_ksymbol_mod(struct kallsym_iter *iter) { - int ret = module_get_kallsym(iter->pos - kallsyms_num_syms, + int ret = module_get_kallsym(iter->pos - iter->pos_arch_end, &iter->value, &iter->type, iter->name, iter->module_name, &iter->exported); @@ -501,6 +522,7 @@ static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) iter->nameoff = get_symbol_offset(new_pos); iter->pos = new_pos; if (new_pos == 0) { + iter->pos_arch_end = 0; iter->pos_mod_end = 0; iter->pos_ftrace_mod_end = 0; } @@ -515,6 +537,10 @@ static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) { iter->pos = pos; + if ((!iter->pos_arch_end || iter->pos_arch_end > pos) && + get_ksymbol_arch(iter)) + return 1; + if ((!iter->pos_mod_end || iter->pos_mod_end > pos) && get_ksymbol_mod(iter)) return 1; ^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH V4 3/3] x86: Add entry trampolines to kcore 2018-06-06 12:54 [PATCH V4 0/3] perf tools and x86 PTI entry trampolines Adrian Hunter 2018-06-06 12:54 ` [PATCH V4 1/3] kallsyms: Simplify update_iter_mod() Adrian Hunter 2018-06-06 12:54 ` [PATCH V4 2/3] kallsyms, x86: Export addresses of PTI entry trampolines Adrian Hunter @ 2018-06-06 12:54 ` Adrian Hunter 2018-06-06 13:16 ` Peter Zijlstra 2018-08-18 12:00 ` [tip:perf/urgent] " tip-bot for Adrian Hunter 2 siblings, 2 replies; 17+ messages in thread From: Adrian Hunter @ 2018-06-06 12:54 UTC (permalink / raw) To: Thomas Gleixner, Arnaldo Carvalho de Melo Cc: Ingo Molnar, Peter Zijlstra, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86 Without program headers for PTI entry trampoline pages, the trampoline virtual addresses do not map to anything. Example before: sudo gdb --quiet vmlinux /proc/kcore Reading symbols from vmlinux...done. [New process 1] Core was generated by `BOOT_IMAGE=/boot/vmlinuz-4.16.0 root=UUID=a6096b83-b763-4101-807e-f33daff63233'. #0 0x0000000000000000 in irq_stack_union () (gdb) x /21ib 0xfffffe0000006000 0xfffffe0000006000: Cannot access memory at address 0xfffffe0000006000 (gdb) quit After: sudo gdb --quiet vmlinux /proc/kcore [sudo] password for ahunter: Reading symbols from vmlinux...done. [New process 1] Core was generated by `BOOT_IMAGE=/boot/vmlinuz-4.16.0-fix-4-00005-gd6e65a8b4072 root=UUID=a6096b83-b7'. #0 0x0000000000000000 in irq_stack_union () (gdb) x /21ib 0xfffffe0000006000 0xfffffe0000006000: swapgs 0xfffffe0000006003: mov %rsp,-0x3e12(%rip) # 0xfffffe00000021f8 0xfffffe000000600a: xchg %ax,%ax 0xfffffe000000600c: mov %cr3,%rsp 0xfffffe000000600f: bts $0x3f,%rsp 0xfffffe0000006014: and $0xffffffffffffe7ff,%rsp 0xfffffe000000601b: mov %rsp,%cr3 0xfffffe000000601e: mov -0x3019(%rip),%rsp # 0xfffffe000000300c 0xfffffe0000006025: pushq $0x2b 0xfffffe0000006027: pushq -0x3e35(%rip) # 0xfffffe00000021f8 0xfffffe000000602d: push %r11 0xfffffe000000602f: pushq $0x33 0xfffffe0000006031: push %rcx 0xfffffe0000006032: push %rdi 0xfffffe0000006033: mov $0xffffffff91a00010,%rdi 0xfffffe000000603a: callq 0xfffffe0000006046 0xfffffe000000603f: pause 0xfffffe0000006041: lfence 0xfffffe0000006044: jmp 0xfffffe000000603f 0xfffffe0000006046: mov %rdi,(%rsp) 0xfffffe000000604a: retq (gdb) quit In addition, entry trampolines all map to the same page. Represent that by giving the corresponding program headers in kcore the same offset. This has the benefit that, when perf tools uses /proc/kcore as a source for kernel object code, samples from different CPU trampolines are aggregated together. Note, such aggregation is normal for profiling i.e. people want to profile the object code, not every different virtual address the object code might be mapped to (across different processes for example). Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Acked-by: Andi Kleen <ak@linux.intel.com> --- arch/x86/mm/cpu_entry_area.c | 10 ++++++++++ fs/proc/kcore.c | 7 +++++-- include/linux/kcore.h | 13 +++++++++++++ 3 files changed, 28 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c index fab49fd5190f..076ebdce9bd4 100644 --- a/arch/x86/mm/cpu_entry_area.c +++ b/arch/x86/mm/cpu_entry_area.c @@ -3,6 +3,7 @@ #include <linux/spinlock.h> #include <linux/percpu.h> #include <linux/kallsyms.h> +#include <linux/kcore.h> #include <asm/cpu_entry_area.h> #include <asm/pgtable.h> @@ -14,6 +15,7 @@ #ifdef CONFIG_X86_64 static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks [(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]); +static DEFINE_PER_CPU(struct kcore_list, kcore_entry_trampoline); #endif struct cpu_entry_area *get_cpu_entry_area(int cpu) @@ -147,6 +149,14 @@ static void __init setup_cpu_entry_area(int cpu) cea_set_pte(&get_cpu_entry_area(cpu)->entry_trampoline, __pa_symbol(_entry_trampoline), PAGE_KERNEL_RX); + /* + * The cpu_entry_area alias addresses are not in the kernel binary + * so they do not show up in /proc/kcore normally. This adds entries + * for them manually. + */ + kclist_add_remap(&per_cpu(kcore_entry_trampoline, cpu), + _entry_trampoline, + &get_cpu_entry_area(cpu)->entry_trampoline, PAGE_SIZE); #endif percpu_setup_debug_store(cpu); } diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index e64ecb9f2720..00282f134336 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -383,8 +383,11 @@ static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff) phdr->p_type = PT_LOAD; phdr->p_flags = PF_R|PF_W|PF_X; phdr->p_offset = kc_vaddr_to_offset(m->addr) + dataoff; - phdr->p_vaddr = (size_t)m->addr; - if (m->type == KCORE_RAM || m->type == KCORE_TEXT) + if (m->type == KCORE_REMAP) + phdr->p_vaddr = (size_t)m->vaddr; + else + phdr->p_vaddr = (size_t)m->addr; + if (m->type == KCORE_RAM || m->type == KCORE_TEXT || m->type == KCORE_REMAP) phdr->p_paddr = __pa(m->addr); else phdr->p_paddr = (elf_addr_t)-1; diff --git a/include/linux/kcore.h b/include/linux/kcore.h index 80db19d3a505..3a11ce51e137 100644 --- a/include/linux/kcore.h +++ b/include/linux/kcore.h @@ -12,11 +12,13 @@ enum kcore_type { KCORE_VMEMMAP, KCORE_USER, KCORE_OTHER, + KCORE_REMAP, }; struct kcore_list { struct list_head list; unsigned long addr; + unsigned long vaddr; size_t size; int type; }; @@ -30,11 +32,22 @@ struct vmcore { #ifdef CONFIG_PROC_KCORE extern void kclist_add(struct kcore_list *, void *, size_t, int type); +static inline +void kclist_add_remap(struct kcore_list *m, void *addr, void *vaddr, size_t sz) +{ + m->vaddr = (unsigned long)vaddr; + kclist_add(m, addr, sz, KCORE_REMAP); +} #else static inline void kclist_add(struct kcore_list *new, void *addr, size_t size, int type) { } + +static inline +void kclist_add_remap(struct kcore_list *m, void *addr, void *vaddr, size_t sz) +{ +} #endif #endif /* _LINUX_KCORE_H */ -- 1.9.1 ^ permalink raw reply related [flat|nested] 17+ messages in thread
* Re: [PATCH V4 3/3] x86: Add entry trampolines to kcore 2018-06-06 12:54 ` [PATCH V4 3/3] x86: Add entry trampolines to kcore Adrian Hunter @ 2018-06-06 13:16 ` Peter Zijlstra 2018-06-06 13:19 ` Arnaldo Carvalho de Melo 2018-08-18 12:00 ` [tip:perf/urgent] " tip-bot for Adrian Hunter 1 sibling, 1 reply; 17+ messages in thread From: Peter Zijlstra @ 2018-06-06 13:16 UTC (permalink / raw) To: Adrian Hunter Cc: Thomas Gleixner, Arnaldo Carvalho de Melo, Ingo Molnar, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86 On Wed, Jun 06, 2018 at 03:54:11PM +0300, Adrian Hunter wrote: > Without program headers for PTI entry trampoline pages, the trampoline > virtual addresses do not map to anything. > > > In addition, entry trampolines all map to the same page. Represent that by > giving the corresponding program headers in kcore the same offset. > > This has the benefit that, when perf tools uses /proc/kcore as a source for > kernel object code, samples from different CPU trampolines are aggregated > together. Note, such aggregation is normal for profiling i.e. people want > to profile the object code, not every different virtual address the object > code might be mapped to (across different processes for example). > > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > Acked-by: Andi Kleen <ak@linux.intel.com> > --- > arch/x86/mm/cpu_entry_area.c | 10 ++++++++++ > fs/proc/kcore.c | 7 +++++-- > include/linux/kcore.h | 13 +++++++++++++ > 3 files changed, 28 insertions(+), 2 deletions(-) This also adds the KCORE_REMAP functionality, but isn't mentioned at all in the Changelog. Still, looks OK I suppose, Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH V4 3/3] x86: Add entry trampolines to kcore 2018-06-06 13:16 ` Peter Zijlstra @ 2018-06-06 13:19 ` Arnaldo Carvalho de Melo 2018-07-17 8:54 ` Adrian Hunter 0 siblings, 1 reply; 17+ messages in thread From: Arnaldo Carvalho de Melo @ 2018-06-06 13:19 UTC (permalink / raw) To: Peter Zijlstra Cc: Adrian Hunter, Thomas Gleixner, Ingo Molnar, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86 Em Wed, Jun 06, 2018 at 03:16:31PM +0200, Peter Zijlstra escreveu: > On Wed, Jun 06, 2018 at 03:54:11PM +0300, Adrian Hunter wrote: > > Without program headers for PTI entry trampoline pages, the trampoline > > virtual addresses do not map to anything. > > > > > > > In addition, entry trampolines all map to the same page. Represent that by > > giving the corresponding program headers in kcore the same offset. > > > > This has the benefit that, when perf tools uses /proc/kcore as a source for > > kernel object code, samples from different CPU trampolines are aggregated > > together. Note, such aggregation is normal for profiling i.e. people want > > to profile the object code, not every different virtual address the object > > code might be mapped to (across different processes for example). > > > > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > > Acked-by: Andi Kleen <ak@linux.intel.com> > > --- > > arch/x86/mm/cpu_entry_area.c | 10 ++++++++++ > > fs/proc/kcore.c | 7 +++++-- > > include/linux/kcore.h | 13 +++++++++++++ > > 3 files changed, 28 insertions(+), 2 deletions(-) > > This also adds the KCORE_REMAP functionality, but isn't mentioned at all > in the Changelog. > > Still, looks OK I suppose, I can add a note about that, > Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Thanks, giving it some more hours and will apply and try to test it. - Arnaldo ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH V4 3/3] x86: Add entry trampolines to kcore 2018-06-06 13:19 ` Arnaldo Carvalho de Melo @ 2018-07-17 8:54 ` Adrian Hunter 2018-07-17 14:47 ` Arnaldo Carvalho de Melo 0 siblings, 1 reply; 17+ messages in thread From: Adrian Hunter @ 2018-07-17 8:54 UTC (permalink / raw) To: Arnaldo Carvalho de Melo, Peter Zijlstra Cc: Thomas Gleixner, Ingo Molnar, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86 On 06/06/18 16:19, Arnaldo Carvalho de Melo wrote: > Em Wed, Jun 06, 2018 at 03:16:31PM +0200, Peter Zijlstra escreveu: >> On Wed, Jun 06, 2018 at 03:54:11PM +0300, Adrian Hunter wrote: >>> Without program headers for PTI entry trampoline pages, the trampoline >>> virtual addresses do not map to anything. >>> >> >>> >>> In addition, entry trampolines all map to the same page. Represent that by >>> giving the corresponding program headers in kcore the same offset. >>> >>> This has the benefit that, when perf tools uses /proc/kcore as a source for >>> kernel object code, samples from different CPU trampolines are aggregated >>> together. Note, such aggregation is normal for profiling i.e. people want >>> to profile the object code, not every different virtual address the object >>> code might be mapped to (across different processes for example). >>> >>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> >>> Acked-by: Andi Kleen <ak@linux.intel.com> >>> --- >>> arch/x86/mm/cpu_entry_area.c | 10 ++++++++++ >>> fs/proc/kcore.c | 7 +++++-- >>> include/linux/kcore.h | 13 +++++++++++++ >>> 3 files changed, 28 insertions(+), 2 deletions(-) >> >> This also adds the KCORE_REMAP functionality, but isn't mentioned at all >> in the Changelog. >> >> Still, looks OK I suppose, > > I can add a note about that, > >> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > Thanks, giving it some more hours and will apply and try to test it. Any update on this? ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH V4 3/3] x86: Add entry trampolines to kcore 2018-07-17 8:54 ` Adrian Hunter @ 2018-07-17 14:47 ` Arnaldo Carvalho de Melo 0 siblings, 0 replies; 17+ messages in thread From: Arnaldo Carvalho de Melo @ 2018-07-17 14:47 UTC (permalink / raw) To: Adrian Hunter Cc: Peter Zijlstra, Thomas Gleixner, Ingo Molnar, Andy Lutomirski, H. Peter Anvin, Andi Kleen, Alexander Shishkin, Dave Hansen, Joerg Roedel, Jiri Olsa, linux-kernel, x86 Em Tue, Jul 17, 2018 at 11:54:30AM +0300, Adrian Hunter escreveu: > On 06/06/18 16:19, Arnaldo Carvalho de Melo wrote: > > Em Wed, Jun 06, 2018 at 03:16:31PM +0200, Peter Zijlstra escreveu: > >> On Wed, Jun 06, 2018 at 03:54:11PM +0300, Adrian Hunter wrote: > >>> Without program headers for PTI entry trampoline pages, the trampoline > >>> virtual addresses do not map to anything. > >>> > >> > >>> > >>> In addition, entry trampolines all map to the same page. Represent that by > >>> giving the corresponding program headers in kcore the same offset. > >>> > >>> This has the benefit that, when perf tools uses /proc/kcore as a source for > >>> kernel object code, samples from different CPU trampolines are aggregated > >>> together. Note, such aggregation is normal for profiling i.e. people want > >>> to profile the object code, not every different virtual address the object > >>> code might be mapped to (across different processes for example). > >>> > >>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > >>> Acked-by: Andi Kleen <ak@linux.intel.com> > >>> --- > >>> arch/x86/mm/cpu_entry_area.c | 10 ++++++++++ > >>> fs/proc/kcore.c | 7 +++++-- > >>> include/linux/kcore.h | 13 +++++++++++++ > >>> 3 files changed, 28 insertions(+), 2 deletions(-) > >> > >> This also adds the KCORE_REMAP functionality, but isn't mentioned at all > >> in the Changelog. > >> > >> Still, looks OK I suppose, > > > > I can add a note about that, > > > >> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > > > Thanks, giving it some more hours and will apply and try to test it. > > Any update on this? On the post-vacation pile, will get to it. - Arnaldo ^ permalink raw reply [flat|nested] 17+ messages in thread
* [tip:perf/urgent] x86: Add entry trampolines to kcore 2018-06-06 12:54 ` [PATCH V4 3/3] x86: Add entry trampolines to kcore Adrian Hunter 2018-06-06 13:16 ` Peter Zijlstra @ 2018-08-18 12:00 ` tip-bot for Adrian Hunter 1 sibling, 0 replies; 17+ messages in thread From: tip-bot for Adrian Hunter @ 2018-08-18 12:00 UTC (permalink / raw) To: linux-tip-commits Cc: adrian.hunter, acme, mingo, jolsa, alexander.shishkin, joro, ak, hpa, luto, linux-kernel, peterz, dave.hansen, tglx Commit-ID: 6855dc41b24619c3d1de3dbd27dd0546b0e45272 Gitweb: https://git.kernel.org/tip/6855dc41b24619c3d1de3dbd27dd0546b0e45272 Author: Adrian Hunter <adrian.hunter@intel.com> AuthorDate: Wed, 6 Jun 2018 15:54:11 +0300 Committer: Arnaldo Carvalho de Melo <acme@redhat.com> CommitDate: Tue, 14 Aug 2018 19:13:26 -0300 x86: Add entry trampolines to kcore Without program headers for PTI entry trampoline pages, the trampoline virtual addresses do not map to anything. Example before: sudo gdb --quiet vmlinux /proc/kcore Reading symbols from vmlinux...done. [New process 1] Core was generated by `BOOT_IMAGE=/boot/vmlinuz-4.16.0 root=UUID=a6096b83-b763-4101-807e-f33daff63233'. #0 0x0000000000000000 in irq_stack_union () (gdb) x /21ib 0xfffffe0000006000 0xfffffe0000006000: Cannot access memory at address 0xfffffe0000006000 (gdb) quit After: sudo gdb --quiet vmlinux /proc/kcore [sudo] password for ahunter: Reading symbols from vmlinux...done. [New process 1] Core was generated by `BOOT_IMAGE=/boot/vmlinuz-4.16.0-fix-4-00005-gd6e65a8b4072 root=UUID=a6096b83-b7'. #0 0x0000000000000000 in irq_stack_union () (gdb) x /21ib 0xfffffe0000006000 0xfffffe0000006000: swapgs 0xfffffe0000006003: mov %rsp,-0x3e12(%rip) # 0xfffffe00000021f8 0xfffffe000000600a: xchg %ax,%ax 0xfffffe000000600c: mov %cr3,%rsp 0xfffffe000000600f: bts $0x3f,%rsp 0xfffffe0000006014: and $0xffffffffffffe7ff,%rsp 0xfffffe000000601b: mov %rsp,%cr3 0xfffffe000000601e: mov -0x3019(%rip),%rsp # 0xfffffe000000300c 0xfffffe0000006025: pushq $0x2b 0xfffffe0000006027: pushq -0x3e35(%rip) # 0xfffffe00000021f8 0xfffffe000000602d: push %r11 0xfffffe000000602f: pushq $0x33 0xfffffe0000006031: push %rcx 0xfffffe0000006032: push %rdi 0xfffffe0000006033: mov $0xffffffff91a00010,%rdi 0xfffffe000000603a: callq 0xfffffe0000006046 0xfffffe000000603f: pause 0xfffffe0000006041: lfence 0xfffffe0000006044: jmp 0xfffffe000000603f 0xfffffe0000006046: mov %rdi,(%rsp) 0xfffffe000000604a: retq (gdb) quit In addition, entry trampolines all map to the same page. Represent that by giving the corresponding program headers in kcore the same offset. This has the benefit that, when perf tools uses /proc/kcore as a source for kernel object code, samples from different CPU trampolines are aggregated together. Note, such aggregation is normal for profiling i.e. people want to profile the object code, not every different virtual address the object code might be mapped to (across different processes for example). Notes by PeterZ: This also adds the KCORE_REMAP functionality. Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Acked-by: Andi Kleen <ak@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86@kernel.org Link: http://lkml.kernel.org/r/1528289651-4113-4-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> --- arch/x86/mm/cpu_entry_area.c | 10 ++++++++++ fs/proc/kcore.c | 7 +++++-- include/linux/kcore.h | 13 +++++++++++++ 3 files changed, 28 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c index fab49fd5190f..076ebdce9bd4 100644 --- a/arch/x86/mm/cpu_entry_area.c +++ b/arch/x86/mm/cpu_entry_area.c @@ -3,6 +3,7 @@ #include <linux/spinlock.h> #include <linux/percpu.h> #include <linux/kallsyms.h> +#include <linux/kcore.h> #include <asm/cpu_entry_area.h> #include <asm/pgtable.h> @@ -14,6 +15,7 @@ static DEFINE_PER_CPU_PAGE_ALIGNED(struct entry_stack_page, entry_stack_storage) #ifdef CONFIG_X86_64 static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks [(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]); +static DEFINE_PER_CPU(struct kcore_list, kcore_entry_trampoline); #endif struct cpu_entry_area *get_cpu_entry_area(int cpu) @@ -147,6 +149,14 @@ static void __init setup_cpu_entry_area(int cpu) cea_set_pte(&get_cpu_entry_area(cpu)->entry_trampoline, __pa_symbol(_entry_trampoline), PAGE_KERNEL_RX); + /* + * The cpu_entry_area alias addresses are not in the kernel binary + * so they do not show up in /proc/kcore normally. This adds entries + * for them manually. + */ + kclist_add_remap(&per_cpu(kcore_entry_trampoline, cpu), + _entry_trampoline, + &get_cpu_entry_area(cpu)->entry_trampoline, PAGE_SIZE); #endif percpu_setup_debug_store(cpu); } diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index e64ecb9f2720..00282f134336 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -383,8 +383,11 @@ static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff) phdr->p_type = PT_LOAD; phdr->p_flags = PF_R|PF_W|PF_X; phdr->p_offset = kc_vaddr_to_offset(m->addr) + dataoff; - phdr->p_vaddr = (size_t)m->addr; - if (m->type == KCORE_RAM || m->type == KCORE_TEXT) + if (m->type == KCORE_REMAP) + phdr->p_vaddr = (size_t)m->vaddr; + else + phdr->p_vaddr = (size_t)m->addr; + if (m->type == KCORE_RAM || m->type == KCORE_TEXT || m->type == KCORE_REMAP) phdr->p_paddr = __pa(m->addr); else phdr->p_paddr = (elf_addr_t)-1; diff --git a/include/linux/kcore.h b/include/linux/kcore.h index 8de55e4b5ee9..bc088ef96358 100644 --- a/include/linux/kcore.h +++ b/include/linux/kcore.h @@ -12,11 +12,13 @@ enum kcore_type { KCORE_VMEMMAP, KCORE_USER, KCORE_OTHER, + KCORE_REMAP, }; struct kcore_list { struct list_head list; unsigned long addr; + unsigned long vaddr; size_t size; int type; }; @@ -36,11 +38,22 @@ struct vmcoredd_node { #ifdef CONFIG_PROC_KCORE extern void kclist_add(struct kcore_list *, void *, size_t, int type); +static inline +void kclist_add_remap(struct kcore_list *m, void *addr, void *vaddr, size_t sz) +{ + m->vaddr = (unsigned long)vaddr; + kclist_add(m, addr, sz, KCORE_REMAP); +} #else static inline void kclist_add(struct kcore_list *new, void *addr, size_t size, int type) { } + +static inline +void kclist_add_remap(struct kcore_list *m, void *addr, void *vaddr, size_t sz) +{ +} #endif #endif /* _LINUX_KCORE_H */ ^ permalink raw reply related [flat|nested] 17+ messages in thread
end of thread, other threads:[~2018-08-18 12:00 UTC | newest] Thread overview: 17+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2018-06-06 12:54 [PATCH V4 0/3] perf tools and x86 PTI entry trampolines Adrian Hunter 2018-06-06 12:54 ` [PATCH V4 1/3] kallsyms: Simplify update_iter_mod() Adrian Hunter 2018-06-06 13:13 ` Peter Zijlstra 2018-06-06 18:37 ` Steven Rostedt 2018-06-06 18:59 ` Arnaldo Carvalho de Melo 2018-06-06 19:13 ` Steven Rostedt 2018-06-06 19:47 ` Arnaldo Carvalho de Melo 2018-08-18 11:59 ` [tip:perf/urgent] " tip-bot for Adrian Hunter 2018-06-06 12:54 ` [PATCH V4 2/3] kallsyms, x86: Export addresses of PTI entry trampolines Adrian Hunter 2018-06-06 13:14 ` Peter Zijlstra 2018-08-18 11:59 ` [tip:perf/urgent] " tip-bot for Alexander Shishkin 2018-06-06 12:54 ` [PATCH V4 3/3] x86: Add entry trampolines to kcore Adrian Hunter 2018-06-06 13:16 ` Peter Zijlstra 2018-06-06 13:19 ` Arnaldo Carvalho de Melo 2018-07-17 8:54 ` Adrian Hunter 2018-07-17 14:47 ` Arnaldo Carvalho de Melo 2018-08-18 12:00 ` [tip:perf/urgent] " tip-bot for Adrian Hunter
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