diff options
author | Peter Zijlstra <peterz@infradead.org> | 2017-02-02 14:43:51 +0100 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2017-03-27 10:20:28 +0200 |
commit | 9a93848fe787a53aec404e4e00d8f7f9bbdaebb4 (patch) | |
tree | 4e3b4f0b97838278a72f47a4b4ed2825610e1969 /arch/x86/kernel | |
parent | 1fa9d67a2f07893fc7e4a880867a6cbb81dda547 (diff) |
x86/debug: Implement __WARN() using UD0
By using "UD0" for WARN()s we remove the function call and its possible
__FILE__ and __LINE__ immediate arguments from the instruction stream.
Total image size will not change much, what we win in the instruction
stream we'll lose because of the __bug_table entries. Still, saves on
I$ footprint and the total image size does go down a bit.
text data filename
10702123 4530992 defconfig-build/vmlinux.orig
10682460 4530992 defconfig-build/vmlinux.patched
(UML didn't seem to use GENERIC_BUG at all, so remove it)
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Weinberger <richard.weinberger@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r-- | arch/x86/kernel/dumpstack.c | 3 | ||||
-rw-r--r-- | arch/x86/kernel/dumpstack_32.c | 12 | ||||
-rw-r--r-- | arch/x86/kernel/dumpstack_64.c | 10 | ||||
-rw-r--r-- | arch/x86/kernel/traps.c | 46 |
4 files changed, 40 insertions, 31 deletions
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 09d4ac0d2661..924f45ea4382 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -289,9 +289,6 @@ void die(const char *str, struct pt_regs *regs, long err) unsigned long flags = oops_begin(); int sig = SIGSEGV; - if (!user_mode(regs)) - report_bug(regs->ip, regs); - if (__die(str, regs, err)) sig = 0; oops_end(flags, regs, sig); diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c index b0b3a3df7c20..e5f0b40e66d2 100644 --- a/arch/x86/kernel/dumpstack_32.c +++ b/arch/x86/kernel/dumpstack_32.c @@ -162,15 +162,3 @@ void show_regs(struct pt_regs *regs) } pr_cont("\n"); } - -int is_valid_bugaddr(unsigned long ip) -{ - unsigned short ud2; - - if (ip < PAGE_OFFSET) - return 0; - if (probe_kernel_address((unsigned short *)ip, ud2)) - return 0; - - return ud2 == 0x0b0f; -} diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index a8b117e93b46..3e1471d57487 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -178,13 +178,3 @@ void show_regs(struct pt_regs *regs) } pr_cont("\n"); } - -int is_valid_bugaddr(unsigned long ip) -{ - unsigned short ud2; - - if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2))) - return 0; - - return ud2 == 0x0b0f; -} diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 948443e115c1..3c0751b120de 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -169,6 +169,37 @@ void ist_end_non_atomic(void) preempt_disable(); } +int is_valid_bugaddr(unsigned long addr) +{ + unsigned short ud; + + if (addr < TASK_SIZE_MAX) + return 0; + + if (probe_kernel_address((unsigned short *)addr, ud)) + return 0; + + return ud == INSN_UD0 || ud == INSN_UD2; +} + +static int fixup_bug(struct pt_regs *regs, int trapnr) +{ + if (trapnr != X86_TRAP_UD) + return 0; + + switch (report_bug(regs->ip, regs)) { + case BUG_TRAP_TYPE_NONE: + case BUG_TRAP_TYPE_BUG: + break; + + case BUG_TRAP_TYPE_WARN: + regs->ip += LEN_UD0; + return 1; + } + + return 0; +} + static nokprobe_inline int do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str, struct pt_regs *regs, long error_code) @@ -187,12 +218,15 @@ do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str, } if (!user_mode(regs)) { - if (!fixup_exception(regs, trapnr)) { - tsk->thread.error_code = error_code; - tsk->thread.trap_nr = trapnr; - die(str, regs, error_code); - } - return 0; + if (fixup_exception(regs, trapnr)) + return 0; + + if (fixup_bug(regs, trapnr)) + return 0; + + tsk->thread.error_code = error_code; + tsk->thread.trap_nr = trapnr; + die(str, regs, error_code); } return -1; |