Linux v4.20-rc7-6-gddfbab46539f
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Justin M. Forbes
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173
bpf-fix-bpf_jit_limit-knob.patch
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173
bpf-fix-bpf_jit_limit-knob.patch
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From fdadd04931c2d7cd294dc5b2b342863f94be53a3 Mon Sep 17 00:00:00 2001
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From: Daniel Borkmann <daniel@iogearbox.net>
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Date: Tue, 11 Dec 2018 12:14:12 +0100
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Subject: bpf: fix bpf_jit_limit knob for PAGE_SIZE >= 64K
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Michael and Sandipan report:
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Commit ede95a63b5 introduced a bpf_jit_limit tuneable to limit BPF
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JIT allocations. At compile time it defaults to PAGE_SIZE * 40000,
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and is adjusted again at init time if MODULES_VADDR is defined.
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For ppc64 kernels, MODULES_VADDR isn't defined, so we're stuck with
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the compile-time default at boot-time, which is 0x9c400000 when
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using 64K page size. This overflows the signed 32-bit bpf_jit_limit
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value:
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root@ubuntu:/tmp# cat /proc/sys/net/core/bpf_jit_limit
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-1673527296
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and can cause various unexpected failures throughout the network
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stack. In one case `strace dhclient eth0` reported:
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setsockopt(5, SOL_SOCKET, SO_ATTACH_FILTER, {len=11, filter=0x105dd27f8},
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16) = -1 ENOTSUPP (Unknown error 524)
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and similar failures can be seen with tools like tcpdump. This doesn't
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always reproduce however, and I'm not sure why. The more consistent
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failure I've seen is an Ubuntu 18.04 KVM guest booted on a POWER9
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host would time out on systemd/netplan configuring a virtio-net NIC
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with no noticeable errors in the logs.
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Given this and also given that in near future some architectures like
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arm64 will have a custom area for BPF JIT image allocations we should
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get rid of the BPF_JIT_LIMIT_DEFAULT fallback / default entirely. For
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4.21, we have an overridable bpf_jit_alloc_exec(), bpf_jit_free_exec()
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so therefore add another overridable bpf_jit_alloc_exec_limit() helper
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function which returns the possible size of the memory area for deriving
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the default heuristic in bpf_jit_charge_init().
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Like bpf_jit_alloc_exec() and bpf_jit_free_exec(), the new
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bpf_jit_alloc_exec_limit() assumes that module_alloc() is the default
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JIT memory provider, and therefore in case archs implement their custom
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module_alloc() we use MODULES_{END,_VADDR} for limits and otherwise for
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vmalloc_exec() cases like on ppc64 we use VMALLOC_{END,_START}.
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Additionally, for archs supporting large page sizes, we should change
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the sysctl to be handled as long to not run into sysctl restrictions
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in future.
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Fixes: ede95a63b5e8 ("bpf: add bpf_jit_limit knob to restrict unpriv allocations")
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Reported-by: Sandipan Das <sandipan@linux.ibm.com>
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Reported-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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---
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include/linux/filter.h | 2 +-
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kernel/bpf/core.c | 21 +++++++++++++++------
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net/core/sysctl_net_core.c | 20 +++++++++++++++++---
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3 files changed, 33 insertions(+), 10 deletions(-)
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diff --git a/include/linux/filter.h b/include/linux/filter.h
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index 795ff0b869bb..a8b9d90a8042 100644
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--- a/include/linux/filter.h
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+++ b/include/linux/filter.h
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@@ -861,7 +861,7 @@ bpf_run_sk_reuseport(struct sock_reuseport *reuse, struct sock *sk,
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extern int bpf_jit_enable;
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extern int bpf_jit_harden;
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extern int bpf_jit_kallsyms;
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-extern int bpf_jit_limit;
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+extern long bpf_jit_limit;
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typedef void (*bpf_jit_fill_hole_t)(void *area, unsigned int size);
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diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
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index b1a3545d0ec8..b2890c268cb3 100644
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--- a/kernel/bpf/core.c
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+++ b/kernel/bpf/core.c
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@@ -365,13 +365,11 @@ void bpf_prog_kallsyms_del_all(struct bpf_prog *fp)
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}
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#ifdef CONFIG_BPF_JIT
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-# define BPF_JIT_LIMIT_DEFAULT (PAGE_SIZE * 40000)
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-
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/* All BPF JIT sysctl knobs here. */
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int bpf_jit_enable __read_mostly = IS_BUILTIN(CONFIG_BPF_JIT_ALWAYS_ON);
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int bpf_jit_harden __read_mostly;
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int bpf_jit_kallsyms __read_mostly;
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-int bpf_jit_limit __read_mostly = BPF_JIT_LIMIT_DEFAULT;
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+long bpf_jit_limit __read_mostly;
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static __always_inline void
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bpf_get_prog_addr_region(const struct bpf_prog *prog,
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@@ -580,16 +578,27 @@ int bpf_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
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static atomic_long_t bpf_jit_current;
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+/* Can be overridden by an arch's JIT compiler if it has a custom,
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+ * dedicated BPF backend memory area, or if neither of the two
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+ * below apply.
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+ */
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+u64 __weak bpf_jit_alloc_exec_limit(void)
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+{
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#if defined(MODULES_VADDR)
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+ return MODULES_END - MODULES_VADDR;
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+#else
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+ return VMALLOC_END - VMALLOC_START;
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+#endif
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+}
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+
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static int __init bpf_jit_charge_init(void)
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{
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/* Only used as heuristic here to derive limit. */
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- bpf_jit_limit = min_t(u64, round_up((MODULES_END - MODULES_VADDR) >> 2,
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- PAGE_SIZE), INT_MAX);
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+ bpf_jit_limit = min_t(u64, round_up(bpf_jit_alloc_exec_limit() >> 2,
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+ PAGE_SIZE), LONG_MAX);
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return 0;
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}
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pure_initcall(bpf_jit_charge_init);
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-#endif
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static int bpf_jit_charge_modmem(u32 pages)
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{
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diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
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index 37b4667128a3..d67ec17f2cc8 100644
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--- a/net/core/sysctl_net_core.c
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+++ b/net/core/sysctl_net_core.c
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@@ -28,6 +28,8 @@ static int two __maybe_unused = 2;
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static int min_sndbuf = SOCK_MIN_SNDBUF;
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static int min_rcvbuf = SOCK_MIN_RCVBUF;
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static int max_skb_frags = MAX_SKB_FRAGS;
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+static long long_one __maybe_unused = 1;
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+static long long_max __maybe_unused = LONG_MAX;
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static int net_msg_warn; /* Unused, but still a sysctl */
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@@ -289,6 +291,17 @@ proc_dointvec_minmax_bpf_restricted(struct ctl_table *table, int write,
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return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
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}
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+
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+static int
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+proc_dolongvec_minmax_bpf_restricted(struct ctl_table *table, int write,
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+ void __user *buffer, size_t *lenp,
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+ loff_t *ppos)
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+{
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+ if (!capable(CAP_SYS_ADMIN))
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+ return -EPERM;
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+
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+ return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
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+}
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#endif
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static struct ctl_table net_core_table[] = {
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@@ -398,10 +411,11 @@ static struct ctl_table net_core_table[] = {
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{
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.procname = "bpf_jit_limit",
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.data = &bpf_jit_limit,
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- .maxlen = sizeof(int),
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+ .maxlen = sizeof(long),
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.mode = 0600,
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- .proc_handler = proc_dointvec_minmax_bpf_restricted,
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- .extra1 = &one,
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+ .proc_handler = proc_dolongvec_minmax_bpf_restricted,
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+ .extra1 = &long_one,
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+ .extra2 = &long_max,
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},
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#endif
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{
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--
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cgit 1.2-0.3.lf.el7
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2
gitrev
2
gitrev
@ -1 +1 @@
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7566ec393f4161572ba6f11ad5171fd5d59b0fbd
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ddfbab46539f2d37a9e9d357b054486b51f7dc27
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11
kernel.spec
11
kernel.spec
@ -69,7 +69,7 @@ Summary: The Linux kernel
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# The rc snapshot level
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%global rcrev 7
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# The git snapshot level
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%define gitrev 0
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%define gitrev 1
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# Set rpm version accordingly
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%define rpmversion 4.%{upstream_sublevel}.0
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%endif
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@ -122,7 +122,7 @@ Summary: The Linux kernel
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# Set debugbuildsenabled to 1 for production (build separate debug kernels)
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# and 0 for rawhide (all kernels are debug kernels).
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# See also 'make debug' and 'make release'.
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%define debugbuildsenabled 1
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%define debugbuildsenabled 0
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# Kernel headers are being split out into a separate package
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%if 0%{?fedora}
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@ -612,6 +612,9 @@ Patch504: iio-accel-kxcjk1013-Add-more-hardware-ids.patch
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# rhbz 1645070 patch queued upstream for merging into 4.21
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Patch505: asus-fx503-keyb.patch
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# rhbz 1647947
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Patch506: bpf-fix-bpf_jit_limit-knob.patch
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# END OF PATCH DEFINITIONS
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%endif
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@ -1884,6 +1887,10 @@ fi
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#
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#
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%changelog
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* Tue Dec 18 2018 Justin M. Forbes <jforbes@fedoraproject.org> - 4.20.0-0.rc7.git1.1
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- Linux v4.20-rc7-6-gddfbab46539f
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- Reenable debugging options.
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* Mon Dec 17 2018 Justin M. Forbes <jforbes@fedoraproject.org> - 4.20.0-0.rc7.git0.1
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- Linux v4.20-rc7
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1
sources
1
sources
@ -1,2 +1,3 @@
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SHA512 (linux-4.19.tar.xz) = ab67cc746b375a8b135e8b23e35e1d6787930d19b3c26b2679787d62951cbdbc3bb66f8ededeb9b890e5008b2459397f9018f1a6772fdef67780b06a4cb9f6f4
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SHA512 (patch-4.20-rc7.xz) = 84c35b95f08454f3920b1400e6fee8c6f30ebfdcc9a32f447d2124867b22a17da87c0d1496dd22512ddb4d6c0ce9457acddb6d6167e8c673d44b3f2a585486bd
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SHA512 (patch-4.20-rc7-git1.xz) = 1be1f4d521267a23b3682926dd7b6cf638d8bd1073dd14575007b7736714668229fd2e0b6532e50d9ff07a3079210741e3bd37c52ecab9706435db546e495f51
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