1. 18 Jun, 2020 3 commits
  2. 17 Jun, 2020 10 commits
    • Arnaldo Carvalho de Melo's avatar
      tools headers UAPI: Sync linux/fs.h with the kernel sources · 0e093c77
      Arnaldo Carvalho de Melo authored
      To pick the changes from:
      
        b383a73f ("fs/ext4: Introduce DAX inode flag")
      
      And silence this perf build warning:
      
        Warning: Kernel ABI header at 'tools/include/uapi/linux/fs.h' differs from latest version at 'include/uapi/linux/fs.h'
        diff -u tools/include/uapi/linux/fs.h include/uapi/linux/fs.h
      
      It causes various beautifiers for things like fspick, fsmount, etc (see
      below) to get rebuilt, but this specific change doesn't make 'perf
      trace' be capable of decoding anything new, as we still don't decode
      what comes from ioctls, just its cmds.
      
      Details about the update:
      
        $ cp include/uapi/linux/fs.h tools/include/uapi/linux/fs.h
        $ git diff
        diff --git a/tools/include/uapi/linux/fs.h b/tools/include/uapi/linux/fs.h
        index 379a612f8f1d..f44eb0a04afd 100644
        --- a/tools/include/uapi/linux/fs.h
        +++ b/tools/include/uapi/linux/fs.h
        @@ -262,6 +262,7 @@ struct fsxattr {
         #define FS_EA_INODE_FL                 0x00200000 /* Inode used for large EA */
         #define FS_EOFBLOCKS_FL                        0x00400000 /* Reserved for ext4 */
         #define FS_NOCOW_FL                    0x00800000 /* Do not cow file */
        +#define FS_DAX_FL                      0x02000000 /* Inode is DAX */
         #define FS_INLINE_DATA_FL              0x10000000 /* Reserved for ext4 */
         #define FS_PROJINHERIT_FL              0x20000000 /* Create with parents projid */
         #define FS_CASEFOLD_FL                 0x40000000 /* Folder is case insensitive */
        $ m
        make: Entering directory '/home/acme/git/perf/tools/perf'
          BUILD:   Doing 'make -j8' parallel build
          INSTALL  GTK UI
          CC       /tmp/build/perf/builtin-trace.o
          DESCEND  plugins
          CC       /tmp/build/perf/trace/beauty/fsmount.o
          CC       /tmp/build/perf/trace/beauty/fspick.o
          CC       /tmp/build/perf/trace/beauty/mount_flags.o
          CC       /tmp/build/perf/trace/beauty/move_mount.o
          CC       /tmp/build/perf/trace/beauty/renameat.o
          CC       /tmp/build/perf/trace/beauty/sync_file_range.o
          INSTALL  trace_plugins
          LD       /tmp/build/perf/trace/beauty/perf-in.o
          LD       /tmp/build/perf/perf-in.o
          LINK     /tmp/build/perf/perf
        <SNIP>
      
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Ira Weiny <ira.weiny@intel.com>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Namhyung Kim <namhyung@kernel.org>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      0e093c77
    • Arnaldo Carvalho de Melo's avatar
      tools include UAPI: Sync linux/vhost.h with the kernel sources · f64925c1
      Arnaldo Carvalho de Melo authored
      To get the changes in:
      
        776f3950 ("vhost_vdpa: Support config interrupt in vdpa")
      
      Silencing this perf build warning:
      
        Warning: Kernel ABI header at 'tools/include/uapi/linux/vhost.h' differs from latest version at 'include/uapi/linux/vhost.h'
        diff -u tools/include/uapi/linux/vhost.h include/uapi/linux/vhost.h
      
      This automatically picks the new ioctl introduced in the above patch,
      making tools such as 'perf trace' aware of them and possibly allowing to
      use the strings in filters, etc:
      
        # perf trace -e ioctl --pid 7951
        <SNIP>
           0.178 ( 0.010 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
           0.194 ( 0.010 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
           0.209 ( 0.010 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
           0.224 (249.413 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         249.660 ( 0.011 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         249.675 ( 0.007 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         249.686 ( 0.007 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         249.697 ( 0.008 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         249.709 ( 0.007 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         249.720 ( 0.007 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         249.730 ( 0.007 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         249.740 ( 0.007 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         249.752 ( 0.007 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         249.762 ( 0.007 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         249.772 ( 0.007 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         249.782 (120.138 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         370.201 ( 0.039 ms): CPU 0/KVM/8023 ioctl(fd: 12, cmd: KVM_IRQ_LINE_STATUS, arg: 0x7f744f9e1420) = 0
         370.254 ( 0.052 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         370.575 ( 0.365 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         370.973 ( 0.028 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         371.015 ( 0.037 ms): CPU 0/KVM/8023 ioctl(fd: 14, cmd: KVM_RUN) = 0
         371.071 ( 0.009 ms): CPU 0/KVM/8023 ioctl(fd: 12, cmd: KVM_IRQ_LINE_STATUS, arg: 0x7f744f9e14b0) = 0
        <SNIP>
        #
      
      Details about the update:
      
        $ diff -u tools/include/uapi/linux/vhost.h include/uapi/linux/vhost.h
        --- tools/include/uapi/linux/vhost.h	2020-04-16 13:19:12.056763843 -0300
        +++ include/uapi/linux/vhost.h	2020-06-17 10:04:20.532056428 -0300
        @@ -15,6 +15,8 @@
         #include <linux/types.h>
         #include <linux/ioctl.h>
      
        +#define VHOST_FILE_UNBIND -1
        +
         /* ioctls */
      
         #define VHOST_VIRTIO 0xAF
        @@ -140,4 +142,6 @@
         /* Get the max ring size. */
         #define VHOST_VDPA_GET_VRING_NUM	_IOR(VHOST_VIRTIO, 0x76, __u16)
      
        +/* Set event fd for config interrupt*/
        +#define VHOST_VDPA_SET_CONFIG_CALL	_IOW(VHOST_VIRTIO, 0x77, int)
         #endif
        $
        $ tools/perf/trace/beauty/vhost_virtio_ioctl.sh > before
        $ cp include/uapi/linux/vhost.h tools/include/uapi/linux/vhost.h
        $ tools/perf/trace/beauty/vhost_virtio_ioctl.sh > after
        $ diff -u before after
        --- before	2020-06-17 10:15:35.123275966 -0300
        +++ after	2020-06-17 10:15:51.812482117 -0300
        @@ -27,6 +27,7 @@
         	[0x72] = "VDPA_SET_STATUS",
         	[0x74] = "VDPA_SET_CONFIG",
         	[0x75] = "VDPA_SET_VRING_ENABLE",
        +	[0x77] = "VDPA_SET_CONFIG_CALL",
         };
         static const char *vhost_virtio_ioctl_read_cmds[] = {
         	[0x00] = "GET_FEATURES",
        $
      
      This causes these parts to get rebuilt:
      
        CC       /tmp/build/perf/trace/beauty/ioctl.o
        INSTALL  trace_plugins
        LD       /tmp/build/perf/trace/beauty/perf-in.o
        LD       /tmp/build/perf/perf-in.o
        LINK     /tmp/build/perf/perf
      
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Michael S. Tsirkin <mst@redhat.com>
      Cc: Namhyung Kim <namhyung@kernel.org>
      Cc: Zhu Lingshan <lingshan.zhu@intel.com>
      Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      f64925c1
    • Arnaldo Carvalho de Melo's avatar
      tools arch x86: Sync the msr-index.h copy with the kernel sources · 25ca7e5c
      Arnaldo Carvalho de Melo authored
      To pick up the changes in:
      
        7e5b3c26 ("x86/speculation: Add Special Register Buffer Data Sampling (SRBDS) mitigation")
      
      Addressing these tools/perf build warnings:
      
        Warning: Kernel ABI header at 'tools/arch/x86/include/asm/msr-index.h' differs from latest version at 'arch/x86/include/asm/msr-index.h'
        diff -u tools/arch/x86/include/asm/msr-index.h arch/x86/include/asm/msr-index.h
        Warning: Kernel ABI header at 'tools/arch/x86/include/asm/cpufeatures.h' differs from latest version at 'arch/x86/include/asm/cpufeatures.h'
        diff -u tools/arch/x86/include/asm/cpufeatures.h arch/x86/include/asm/cpufeatures.h
      
      With this one will be able to use these new AMD MSRs in filters, by
      name, e.g.:
      
        # perf trace -e msr:* --filter "msr==IA32_MCU_OPT_CTRL"
        ^C#
      
      Using -v we can see how it sets up the tracepoint filters, converting
      from the string in the filter to the numeric value:
      
        # perf trace -v -e msr:* --filter "msr==IA32_MCU_OPT_CTRL"
        Using CPUID GenuineIntel-6-8E-A
        0x123
        New filter for msr:read_msr: (msr==0x123) && (common_pid != 335 && common_pid != 30344)
        0x123
        New filter for msr:write_msr: (msr==0x123) && (common_pid != 335 && common_pid != 30344)
        0x123
        New filter for msr:rdpmc: (msr==0x123) && (common_pid != 335 && common_pid != 30344)
        mmap size 528384B
        ^C#
      
      The updating process shows how this affects tooling in more detail:
      
        $ diff -u tools/arch/x86/include/asm/msr-index.h arch/x86/include/asm/msr-index.h
        --- tools/arch/x86/include/asm/msr-index.h	2020-06-03 10:36:09.959910238 -0300
        +++ arch/x86/include/asm/msr-index.h	2020-06-17 10:04:20.235052901 -0300
        @@ -128,6 +128,10 @@
         #define TSX_CTRL_RTM_DISABLE		BIT(0)	/* Disable RTM feature */
         #define TSX_CTRL_CPUID_CLEAR		BIT(1)	/* Disable TSX enumeration */
      
        +/* SRBDS support */
        +#define MSR_IA32_MCU_OPT_CTRL		0x00000123
        +#define RNGDS_MITG_DIS			BIT(0)
        +
         #define MSR_IA32_SYSENTER_CS		0x00000174
         #define MSR_IA32_SYSENTER_ESP		0x00000175
         #define MSR_IA32_SYSENTER_EIP		0x00000176
        $ set -o vi
        $ tools/perf/trace/beauty/tracepoints/x86_msr.sh > before
        $ cp arch/x86/include/asm/msr-index.h tools/arch/x86/include/asm/msr-index.h
        $ tools/perf/trace/beauty/tracepoints/x86_msr.sh > after
        $ diff -u before after
        --- before	2020-06-17 10:05:49.653114752 -0300
        +++ after	2020-06-17 10:06:01.777258731 -0300
        @@ -51,6 +51,7 @@
         	[0x0000011e] = "IA32_BBL_CR_CTL3",
         	[0x00000120] = "IDT_MCR_CTRL",
         	[0x00000122] = "IA32_TSX_CTRL",
        +	[0x00000123] = "IA32_MCU_OPT_CTRL",
         	[0x00000140] = "MISC_FEATURES_ENABLES",
         	[0x00000174] = "IA32_SYSENTER_CS",
         	[0x00000175] = "IA32_SYSENTER_ESP",
        $
      
      The related change to cpu-features.h affects this:
      
        CC       /tmp/build/perf/bench/mem-memcpy-x86-64-asm.o
        CC       /tmp/build/perf/bench/mem-memset-x86-64-asm.o
      
      This shouldn't be affecting that 'perf bench' entry:
      
        $ find tools/perf/ -type f | xargs grep SRBDS
        $
      
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Mark Gross <mgross@linux.intel.com>
      Cc: Namhyung Kim <namhyung@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      25ca7e5c
    • Arnaldo Carvalho de Melo's avatar
      Merge remote-tracking branch 'torvalds/master' into perf/urgent · 08a7c777
      Arnaldo Carvalho de Melo authored
      To get some newer headers that got out of sync with the copies in tools/
      so that we can try to have the tools/perf/ build clean for v5.8 with
      fewer pull requests.
      Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      08a7c777
    • Milian Wolff's avatar
      perf script: Initialize zstd_data · b13b04d9
      Milian Wolff authored
      Fixes segmentation fault when trying to interpret zstd-compressed data
      with perf script:
      
      ```
        $ perf record -z ls
        ...
        [ perf record: Captured and wrote 0,010 MB perf.data, compressed (original 0,001 MB, ratio is 2,190) ]
        $ memcheck perf script
        ...
        ==67911== Invalid read of size 4
        ==67911==    at 0x5568188: ZSTD_decompressStream (in /usr/lib/libzstd.so.1.4.5)
        ==67911==    by 0x6E726B: zstd_decompress_stream (zstd.c:100)
        ==67911==    by 0x65729C: perf_session__process_compressed_event (session.c:72)
        ==67911==    by 0x6598E8: perf_session__process_user_event (session.c:1583)
        ==67911==    by 0x65BA59: reader__process_events (session.c:2177)
        ==67911==    by 0x65BA59: __perf_session__process_events (session.c:2234)
        ==67911==    by 0x65BA59: perf_session__process_events (session.c:2267)
        ==67911==    by 0x5A7397: __cmd_script (builtin-script.c:2447)
        ==67911==    by 0x5A7397: cmd_script (builtin-script.c:3840)
        ==67911==    by 0x5FE9D2: run_builtin (perf.c:312)
        ==67911==    by 0x711627: handle_internal_command (perf.c:364)
        ==67911==    by 0x711627: run_argv (perf.c:408)
        ==67911==    by 0x711627: main (perf.c:538)
        ==67911==  Address 0x71d8 is not stack'd, malloc'd or (recently) free'd
      ```
      Signed-off-by: default avatarMilian Wolff <milian.wolff@kdab.com>
      Acked-by: default avatarAlexey Budankov <alexey.budankov@linux.intel.com>
      Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      LPU-Reference: 20200612230333.72140-1-milian.wolff@kdab.com
      Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      b13b04d9
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net · 69119673
      Linus Torvalds authored
      Pull networking fixes from David Miller:
      
       1) Don't get per-cpu pointer with preemption enabled in nft_set_pipapo,
          fix from Stefano Brivio.
      
       2) Fix memory leak in ctnetlink, from Pablo Neira Ayuso.
      
       3) Multiple definitions of MPTCP_PM_MAX_ADDR, from Geliang Tang.
      
       4) Accidently disabling NAPI in non-error paths of macb_open(), from
          Charles Keepax.
      
       5) Fix races between alx_stop and alx_remove, from Zekun Shen.
      
       6) We forget to re-enable SRIOV during resume in bnxt_en driver, from
          Michael Chan.
      
       7) Fix memory leak in ipv6_mc_destroy_dev(), from Wang Hai.
      
       8) rxtx stats use wrong index in mvpp2 driver, from Sven Auhagen.
      
       9) Fix memory leak in mptcp_subflow_create_socket error path, from Wei
          Yongjun.
      
      10) We should not adjust the TCP window advertised when sending dup acks
          in non-SACK mode, because it won't be counted as a dup by the sender
          if the window size changes. From Eric Dumazet.
      
      11) Destroy the right number of queues during remove in mvpp2 driver,
          from Sven Auhagen.
      
      12) Various WOL and PM fixes to e1000 driver, from Chen Yu, Vaibhav
          Gupta, and Arnd Bergmann.
      
      * git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (35 commits)
        e1000e: fix unused-function warning
        e1000: use generic power management
        e1000e: Do not wake up the system via WOL if device wakeup is disabled
        lan743x: add MODULE_DEVICE_TABLE for module loading alias
        mlxsw: spectrum: Adjust headroom buffers for 8x ports
        bareudp: Fixed configuration to avoid having garbage values
        mvpp2: remove module bugfix
        tcp: grow window for OOO packets only for SACK flows
        mptcp: fix memory leak in mptcp_subflow_create_socket()
        netfilter: flowtable: Make nf_flow_table_offload_add/del_cb inline
        net/sched: act_ct: Make tcf_ct_flow_table_restore_skb inline
        net: dsa: sja1105: fix PTP timestamping with large tc-taprio cycles
        mvpp2: ethtool rxtx stats fix
        MAINTAINERS: switch to my private email for Renesas Ethernet drivers
        rocker: fix incorrect error handling in dma_rings_init
        test_objagg: Fix potential memory leak in error handling
        net: ethernet: mtk-star-emac: simplify interrupt handling
        mld: fix memory leak in ipv6_mc_destroy_dev()
        bnxt_en: Return from timer if interface is not in open state.
        bnxt_en: Fix AER reset logic on 57500 chips.
        ...
      69119673
    • Linus Torvalds's avatar
      Merge tag 'afs-fixes-20200616' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs · 26c20ffc
      Linus Torvalds authored
      Pull AFS fixes from David Howells:
       "I've managed to get xfstests kind of working with afs. Here are a set
        of patches that fix most of the bugs found.
      
        There are a number of primary issues:
      
         - Incorrect handling of mtime and non-handling of ctime. It might be
           argued, that the latter isn't a bug since the AFS protocol doesn't
           support ctime, but I should probably still update it locally.
      
         - Shared-write mmap, truncate and writeback bugs. This includes not
           changing i_size under the callback lock, overwriting local i_size
           with the reply from the server after a partial writeback, not
           limiting the writeback from an mmapped page to EOF.
      
         - Checks for an abort code indicating that the primary vnode in an
           operation was deleted by a third-party are done in the wrong place.
      
         - Silly rename bugs. This includes an incomplete conversion to the
           new operation handling, duplicate nlink handling, nlink changing
           not being done inside the callback lock and insufficient handling
           of third-party conflicting directory changes.
      
        And some secondary ones:
      
         - The UAEOVERFLOW abort code should map to EOVERFLOW not EREMOTEIO.
      
         - Remove a couple of unused or incompletely used bits.
      
         - Remove a couple of redundant success checks.
      
        These seem to fix all the data-corruption bugs found by
      
      	./check -afs -g quick
      
        along with the obvious silly rename bugs and time bugs.
      
        There are still some test failures, but they seem to fall into two
        classes: firstly, the authentication/security model is different to
        the standard UNIX model and permission is arbitrated by the server and
        cached locally; and secondly, there are a number of features that AFS
        does not support (such as mknod). But in these cases, the tests
        themselves need to be adapted or skipped.
      
        Using the in-kernel afs client with xfstests also found a bug in the
        AuriStor AFS server that has been fixed for a future release"
      
      * tag 'afs-fixes-20200616' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
        afs: Fix silly rename
        afs: afs_vnode_commit_status() doesn't need to check the RPC error
        afs: Fix use of afs_check_for_remote_deletion()
        afs: Remove afs_operation::abort_code
        afs: Fix yfs_fs_fetch_status() to honour vnode selector
        afs: Remove yfs_fs_fetch_file_status() as it's not used
        afs: Fix the mapping of the UAEOVERFLOW abort code
        afs: Fix truncation issues and mmap writeback size
        afs: Concoct ctimes
        afs: Fix EOF corruption
        afs: afs_write_end() should change i_size under the right lock
        afs: Fix non-setting of mtime when writing into mmap
      26c20ffc
    • Randy Dunlap's avatar
      Documentation: remove SH-5 index entries · f17957f7
      Randy Dunlap authored
      Remove SH-5 documentation index entries following the removal
      of SH-5 source code.
      
      Error: Cannot open file ../arch/sh/mm/tlb-sh5.c
      Error: Cannot open file ../arch/sh/mm/tlb-sh5.c
      Error: Cannot open file ../arch/sh/include/asm/tlb_64.h
      Error: Cannot open file ../arch/sh/include/asm/tlb_64.h
      
      Fixes: 3b69e8b4 ("Merge tag 'sh-for-5.8' of git://git.libc.org/linux-sh")
      Signed-off-by: default avatarRandy Dunlap <rdunlap@infradead.org>
      Reviewed-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
      Cc: Rich Felker <dalias@libc.org>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: ysato@users.sourceforge.jp
      Cc: linux-sh@vger.kernel.org
      Cc: Geert Uytterhoeven <geert@linux-m68k.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f17957f7
    • Linus Torvalds's avatar
      Merge tag 'flex-array-conversions-5.8-rc2' of... · ffbc9376
      Linus Torvalds authored
      Merge tag 'flex-array-conversions-5.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux
      
      Pull flexible-array member conversions from Gustavo A. R. Silva:
       "Replace zero-length arrays with flexible-array members.
      
        Notice that all of these patches have been baking in linux-next for
        two development cycles now.
      
        There is a regular need in the kernel to provide a way to declare
        having a dynamically sized set of trailing elements in a structure.
        Kernel code should always use “flexible array members”[1] for these
        cases. The older style of one-element or zero-length arrays should no
        longer be used[2].
      
        C99 introduced “flexible array members”, which lacks a numeric size
        for the array declaration entirely:
      
              struct something {
                      size_t count;
                      struct foo items[];
              };
      
        This is the way the kernel expects dynamically sized trailing elements
        to be declared. It allows the compiler to generate errors when the
        flexible array does not occur last in the structure, which helps to
        prevent some kind of undefined behavior[3] bugs from being
        inadvertently introduced to the codebase.
      
        It also allows the compiler to correctly analyze array sizes (via
        sizeof(), CONFIG_FORTIFY_SOURCE, and CONFIG_UBSAN_BOUNDS). For
        instance, there is no mechanism that warns us that the following
        application of the sizeof() operator to a zero-length array always
        results in zero:
      
              struct something {
                      size_t count;
                      struct foo items[0];
              };
      
              struct something *instance;
      
              instance = kmalloc(struct_size(instance, items, count), GFP_KERNEL);
              instance->count = count;
      
              size = sizeof(instance->items) * instance->count;
              memcpy(instance->items, source, size);
      
        At the last line of code above, size turns out to be zero, when one
        might have thought it represents the total size in bytes of the
        dynamic memory recently allocated for the trailing array items. Here
        are a couple examples of this issue[4][5].
      
        Instead, flexible array members have incomplete type, and so the
        sizeof() operator may not be applied[6], so any misuse of such
        operators will be immediately noticed at build time.
      
        The cleanest and least error-prone way to implement this is through
        the use of a flexible array member:
      
              struct something {
                      size_t count;
                      struct foo items[];
              };
      
              struct something *instance;
      
              instance = kmalloc(struct_size(instance, items, count), GFP_KERNEL);
              instance->count = count;
      
              size = sizeof(instance->items[0]) * instance->count;
              memcpy(instance->items, source, size);
      
        instead"
      
      [1] https://en.wikipedia.org/wiki/Flexible_array_member
      [2] https://github.com/KSPP/linux/issues/21
      [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
      [4] commit f2cd32a4 ("rndis_wlan: Remove logically dead code")
      [5] commit ab91c2a8 ("tpm: eventlog: Replace zero-length array with flexible-array member")
      [6] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
      
      * tag 'flex-array-conversions-5.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux: (41 commits)
        w1: Replace zero-length array with flexible-array
        tracing/probe: Replace zero-length array with flexible-array
        soc: ti: Replace zero-length array with flexible-array
        tifm: Replace zero-length array with flexible-array
        dmaengine: tegra-apb: Replace zero-length array with flexible-array
        stm class: Replace zero-length array with flexible-array
        Squashfs: Replace zero-length array with flexible-array
        ASoC: SOF: Replace zero-length array with flexible-array
        ima: Replace zero-length array with flexible-array
        sctp: Replace zero-length array with flexible-array
        phy: samsung: Replace zero-length array with flexible-array
        RxRPC: Replace zero-length array with flexible-array
        rapidio: Replace zero-length array with flexible-array
        media: pwc: Replace zero-length array with flexible-array
        firmware: pcdp: Replace zero-length array with flexible-array
        oprofile: Replace zero-length array with flexible-array
        block: Replace zero-length array with flexible-array
        tools/testing/nvdimm: Replace zero-length array with flexible-array
        libata: Replace zero-length array with flexible-array
        kprobes: Replace zero-length array with flexible-array
        ...
      ffbc9376
    • Arvind Sankar's avatar
      x86/purgatory: Add -fno-stack-protector · ff58155c
      Arvind Sankar authored
      The purgatory Makefile removes -fstack-protector options if they were
      configured in, but does not currently add -fno-stack-protector.
      
      If gcc was configured with the --enable-default-ssp configure option,
      this results in the stack protector still being enabled for the
      purgatory (absent distro-specific specs files that might disable it
      again for freestanding compilations), if the main kernel is being
      compiled with stack protection enabled (if it's disabled for the main
      kernel, the top-level Makefile will add -fno-stack-protector).
      
      This will break the build since commit
        e4160b2e ("x86/purgatory: Fail the build if purgatory.ro has missing symbols")
      and prior to that would have caused runtime failure when trying to use
      kexec.
      
      Explicitly add -fno-stack-protector to avoid this, as done in other
      Makefiles that need to disable the stack protector.
      Reported-by: default avatarGabriel C <nix.or.die@googlemail.com>
      Signed-off-by: default avatarArvind Sankar <nivedita@alum.mit.edu>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ff58155c
  3. 16 Jun, 2020 27 commits