From db38d5c106dfdd7cb7207c83267d82fdf4950b61 Mon Sep 17 00:00:00 2001 From: Rafael Aquini Date: Sun, 7 Jun 2020 21:40:17 -0700 Subject: kernel: add panic_on_taint Analogously to the introduction of panic_on_warn, this patch introduces a kernel option named panic_on_taint in order to provide a simple and generic way to stop execution and catch a coredump when the kernel gets tainted by any given flag. This is useful for debugging sessions as it avoids having to rebuild the kernel to explicitly add calls to panic() into the code sites that introduce the taint flags of interest. For instance, if one is interested in proceeding with a post-mortem analysis at the point a given code path is hitting a bad page (i.e. unaccount_page_cache_page(), or slab_bug()), a coredump can be collected by rebooting the kernel with 'panic_on_taint=0x20' amended to the command line. Another, perhaps less frequent, use for this option would be as a means for assuring a security policy case where only a subset of taints, or no single taint (in paranoid mode), is allowed for the running system. The optional switch 'nousertaint' is handy in this particular scenario, as it will avoid userspace induced crashes by writes to sysctl interface /proc/sys/kernel/tainted causing false positive hits for such policies. [akpm@linux-foundation.org: tweak kernel-parameters.txt wording] Suggested-by: Qian Cai Signed-off-by: Rafael Aquini Signed-off-by: Andrew Morton Reviewed-by: Luis Chamberlain Cc: Dave Young Cc: Baoquan He Cc: Jonathan Corbet Cc: Kees Cook Cc: Randy Dunlap Cc: "Theodore Ts'o" Cc: Adrian Bunk Cc: Greg Kroah-Hartman Cc: Laura Abbott Cc: Jeff Mahoney Cc: Jiri Kosina Cc: Takashi Iwai Link: http://lkml.kernel.org/r/20200515175502.146720-1-aquini@redhat.com Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 9b7a8d74a9d6..f7835db7102e 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -528,6 +528,8 @@ extern int panic_on_oops; extern int panic_on_unrecovered_nmi; extern int panic_on_io_nmi; extern int panic_on_warn; +extern unsigned long panic_on_taint; +extern bool panic_on_taint_nousertaint; extern int sysctl_panic_on_rcu_stall; extern int sysctl_panic_on_stackoverflow; @@ -596,6 +598,7 @@ extern enum system_states { #define TAINT_AUX 16 #define TAINT_RANDSTRUCT 17 #define TAINT_FLAGS_COUNT 18 +#define TAINT_FLAGS_MAX ((1UL << TAINT_FLAGS_COUNT) - 1) struct taint_flag { char c_true; /* character printed when tainted */ -- cgit v1.2.3 From 60c958d8df9cfc40b745d6cd583cfbfa7525ead6 Mon Sep 17 00:00:00 2001 From: "Guilherme G. Piccoli" Date: Sun, 7 Jun 2020 21:40:48 -0700 Subject: panic: add sysctl to dump all CPUs backtraces on oops event Usually when the kernel reaches an oops condition, it's a point of no return; in case not enough debug information is available in the kernel splat, one of the last resorts would be to collect a kernel crash dump and analyze it. The problem with this approach is that in order to collect the dump, a panic is required (to kexec-load the crash kernel). When in an environment of multiple virtual machines, users may prefer to try living with the oops, at least until being able to properly shutdown their VMs / finish their important tasks. This patch implements a way to collect a bit more debug details when an oops event is reached, by printing all the CPUs backtraces through the usage of NMIs (on architectures that support that). The sysctl added (and documented) here was called "oops_all_cpu_backtrace", and when set will (as the name suggests) dump all CPUs backtraces. Far from ideal, this may be the last option though for users that for some reason cannot panic on oops. Most of times oopses are clear enough to indicate the kernel portion that must be investigated, but in virtual environments it's possible to observe hypervisor/KVM issues that could lead to oopses shown in other guests CPUs (like virtual APIC crashes). This patch hence aims to help debug such complex issues without resorting to kdump. Signed-off-by: Guilherme G. Piccoli Signed-off-by: Andrew Morton Reviewed-by: Kees Cook Cc: Luis Chamberlain Cc: Iurii Zaikin Cc: Thomas Gleixner Cc: Vlastimil Babka Cc: Randy Dunlap Cc: Matthew Wilcox Link: http://lkml.kernel.org/r/20200327224116.21030-1-gpiccoli@canonical.com Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index f7835db7102e..82d91547d122 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -520,6 +520,12 @@ static inline u32 int_sqrt64(u64 x) } #endif +#ifdef CONFIG_SMP +extern unsigned int sysctl_oops_all_cpu_backtrace; +#else +#define sysctl_oops_all_cpu_backtrace 0 +#endif /* CONFIG_SMP */ + extern void bust_spinlocks(int yes); extern int oops_in_progress; /* If set, an oops, panic(), BUG() or die() is in progress */ extern int panic_timeout; -- cgit v1.2.3 From 229f5879facf96e5640c0385f62b8cb5f27b8a43 Mon Sep 17 00:00:00 2001 From: Kishon Vijay Abraham I Date: Wed, 22 Jul 2020 16:33:05 +0530 Subject: linux/kernel.h: Add PTR_ALIGN_DOWN macro Add a macro for aligning down a pointer. This is useful to get an aligned register address when a device allows only word access and doesn't allow half word or byte access. Link: https://lore.kernel.org/r/20200722110317.4744-4-kishon@ti.com Signed-off-by: Kishon Vijay Abraham I Signed-off-by: Lorenzo Pieralisi Acked-by: Rob Herring --- include/linux/kernel.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 82d91547d122..7339a00c895e 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -34,6 +34,7 @@ #define ALIGN_DOWN(x, a) __ALIGN_KERNEL((x) - ((a) - 1), (a)) #define __ALIGN_MASK(x, mask) __ALIGN_KERNEL_MASK((x), (mask)) #define PTR_ALIGN(p, a) ((typeof(p))ALIGN((unsigned long)(p), (a))) +#define PTR_ALIGN_DOWN(p, a) ((typeof(p))ALIGN_DOWN((unsigned long)(p), (a))) #define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0) /* generic data direction definitions */ -- cgit v1.2.3 From 376653435dacf84a8aca87e66aff94079a817cf2 Mon Sep 17 00:00:00 2001 From: Arvind Sankar Date: Tue, 11 Aug 2020 18:34:16 -0700 Subject: kernel.h: remove duplicate include of asm/div64.h This seems to have been added inadvertently in commit 72deb455b5ec ("block: remove CONFIG_LBDAF") Fixes: 72deb455b5ec ("block: remove CONFIG_LBDAF") Signed-off-by: Arvind Sankar Signed-off-by: Andrew Morton Reviewed-by: Christoph Hellwig Link: http://lkml.kernel.org/r/20200727034852.2813453-1-nivedita@alum.mit.edu Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 7339a00c895e..e19c13616666 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -17,7 +17,6 @@ #include #include #include -#include #define STACK_MAGIC 0xdeadbeef -- cgit v1.2.3 From b642e44e8ab335868b549fe5753b783ca47bf3a3 Mon Sep 17 00:00:00 2001 From: Kars Mulder Date: Tue, 11 Aug 2020 18:34:53 -0700 Subject: kstrto*: correct documentation references to simple_strto*() The documentation of the kstrto*() functions reference the simple_strtoull function by "used as a replacement for [the obsolete] simple_strtoull". All these functions describes themselves as replacements for the function simple_strtoull, even though a function like kstrtol() would be more aptly described as a replacement of simple_strtol(). Fix these references by making the documentation of kstrto*() reference the closest simple_strto*() equivalent available. The functions kstrto[u]int() do not have direct simple_strto[u]int() equivalences, so these are made to refer to simple_strto[u]l() instead. Furthermore, add parentheses after function names, as is standard in kernel documentation. Fixes: 4c925d6031f71 ("kstrto*: add documentation") Signed-off-by: Kars Mulder Signed-off-by: Andrew Morton Reviewed-by: Andy Shevchenko Cc: Eldad Zack Cc: Miguel Ojeda Cc: Geert Uytterhoeven Cc: Mans Rullgard Cc: Petr Mladek Link: http://lkml.kernel.org/r/1ee1-5f234c00-f3-165a6440@234394593 Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index e19c13616666..47b1dad63ffc 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -346,7 +346,7 @@ int __must_check kstrtoll(const char *s, unsigned int base, long long *res); * @res: Where to write the result of the conversion on success. * * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error. - * Used as a replacement for the simple_strtoull. Return code must be checked. + * Used as a replacement for the simple_strtoul(). Return code must be checked. */ static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res) { @@ -374,7 +374,7 @@ static inline int __must_check kstrtoul(const char *s, unsigned int base, unsign * @res: Where to write the result of the conversion on success. * * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error. - * Used as a replacement for the simple_strtoull. Return code must be checked. + * Used as a replacement for the simple_strtol(). Return code must be checked. */ static inline int __must_check kstrtol(const char *s, unsigned int base, long *res) { -- cgit v1.2.3 From ef0f2685336bbc334e8b6997ce9b155e5f7edd31 Mon Sep 17 00:00:00 2001 From: Kars Mulder Date: Tue, 11 Aug 2020 18:34:56 -0700 Subject: kstrto*: do not describe simple_strto*() as obsolete/replaced The documentation of the kstrto*() functions describes kstrto*() as "replacements" of the "obsolete" simple_strto*() functions. Both of these terms are inaccurate: they're not replacements because they have different behaviour, and the simple_strto*() are not obsolete because there are cases where they have benefits over kstrto*(). Remove usage of the terms "replacement" and "obsolete" in reference to simple_strto*(), and instead use the term "preferred over". Fixes: 4c925d6031f71 ("kstrto*: add documentation") Fixes: 885e68e8b7b13 ("kernel.h: update comment about simple_strto() functions") Signed-off-by: Kars Mulder Signed-off-by: Andrew Morton Reviewed-by: Andy Shevchenko Cc: Eldad Zack Cc: Miguel Ojeda Cc: Geert Uytterhoeven Cc: Mans Rullgard Cc: Petr Mladek Link: http://lkml.kernel.org/r/29b9-5f234c80-13-4e3aa200@244003027 Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 47b1dad63ffc..92517ae53e7c 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -346,7 +346,7 @@ int __must_check kstrtoll(const char *s, unsigned int base, long long *res); * @res: Where to write the result of the conversion on success. * * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error. - * Used as a replacement for the simple_strtoul(). Return code must be checked. + * Preferred over simple_strtoul(). Return code must be checked. */ static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res) { @@ -374,7 +374,7 @@ static inline int __must_check kstrtoul(const char *s, unsigned int base, unsign * @res: Where to write the result of the conversion on success. * * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error. - * Used as a replacement for the simple_strtol(). Return code must be checked. + * Preferred over simple_strtol(). Return code must be checked. */ static inline int __must_check kstrtol(const char *s, unsigned int base, long *res) { -- cgit v1.2.3 From 79076e1241bb3bf02d0aac7d39120d8161fe07b1 Mon Sep 17 00:00:00 2001 From: Tiezhu Yang Date: Tue, 11 Aug 2020 18:36:46 -0700 Subject: kernel/panic.c: make oops_may_print() return bool The return value of oops_may_print() is true or false, so change its type to reflect that. Signed-off-by: Tiezhu Yang Signed-off-by: Andrew Morton Reviewed-by: Kees Cook Cc: Xuefeng Li Link: http://lkml.kernel.org/r/1591103358-32087-1-git-send-email-yangtiezhu@loongson.cn Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 92517ae53e7c..211005163682 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -322,7 +322,7 @@ void nmi_panic(struct pt_regs *regs, const char *msg); extern void oops_enter(void); extern void oops_exit(void); void print_oops_end_marker(void); -extern int oops_may_print(void); +extern bool oops_may_print(void); void do_exit(long error_code) __noreturn; void complete_and_exit(struct completion *, long) __noreturn; -- cgit v1.2.3 From 63037f74725ddd8a767ed2ad0369e60a3bf1f2ce Mon Sep 17 00:00:00 2001 From: Yue Hu Date: Tue, 11 Aug 2020 18:36:53 -0700 Subject: panic: make print_oops_end_marker() static Since print_oops_end_marker() is not used externally, also remove it in kernel.h at the same time. Signed-off-by: Yue Hu Signed-off-by: Andrew Morton Cc: Kees Cook Link: http://lkml.kernel.org/r/20200724011516.12756-1-zbestahu@gmail.com Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 211005163682..500def620d8f 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -321,7 +321,6 @@ void panic(const char *fmt, ...) __noreturn __cold; void nmi_panic(struct pt_regs *regs, const char *msg); extern void oops_enter(void); extern void oops_exit(void); -void print_oops_end_marker(void); extern bool oops_may_print(void); void do_exit(long error_code) __noreturn; void complete_and_exit(struct completion *, long) __noreturn; -- cgit v1.2.3 From ef91bb196b0db1013ef8705367bc2d7944ef696b Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Fri, 28 Aug 2020 17:11:25 +1000 Subject: kernel.h: Silence sparse warning in lower_32_bits I keep getting sparse warnings in crypto such as: CHECK drivers/crypto/ccree/cc_hash.c drivers/crypto/ccree/cc_hash.c:49:9: warning: cast truncates bits from constant value (47b5481dbefa4fa4 becomes befa4fa4) drivers/crypto/ccree/cc_hash.c:49:26: warning: cast truncates bits from constant value (db0c2e0d64f98fa7 becomes 64f98fa7) [.. many more ..] This patch removes the warning by adding a mask to keep sparse happy. Signed-off-by: Herbert Xu Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 500def620d8f..c25b8e41c0ea 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -186,7 +186,7 @@ * lower_32_bits - return bits 0-31 of a number * @n: the number we're accessing */ -#define lower_32_bits(n) ((u32)(n)) +#define lower_32_bits(n) ((u32)((n) & 0xffffffff)) struct completion; struct pt_regs; -- cgit v1.2.3