#undef TRACE_SYSTEM #define TRACE_SYSTEM tlb #if !defined(_TRACE_TLB_H) || defined(TRACE_HEADER_MULTI_READ) #define _TRACE_TLB_H #include #include #define TLB_FLUSH_REASON \ EM( TLB_FLUSH_ON_TASK_SWITCH, "flush on task switch" ) \ EM( TLB_REMOTE_SHOOTDOWN, "remote shootdown" ) \ EM( TLB_LOCAL_SHOOTDOWN, "local shootdown" ) \ EM( TLB_LOCAL_MM_SHOOTDOWN, "local mm shootdown" ) \ EMe( TLB_REMOTE_SEND_IPI, "remote ipi send" ) /* * First define the enums in TLB_FLUSH_REASON to be exported to userspace * via TRACE_DEFINE_ENUM(). */ #undef EM #undef EMe #define EM(a,b) TRACE_DEFINE_ENUM(a); #define EMe(a,b) TRACE_DEFINE_ENUM(a); TLB_FLUSH_REASON /* * Now redefine the EM() and EMe() macros to map the enums to the strings * that will be printed in the output. */ #undef EM #undef EMe #define EM(a,b) { a, b }, #define EMe(a,b) { a, b } TRACE_EVENT(tlb_flush, TP_PROTO(int reason, unsigned long pages), TP_ARGS(reason, pages), TP_STRUCT__entry( __field( int, reason) __field(unsigned long, pages) ), TP_fast_assign( __entry->reason = reason; __entry->pages = pages; ), TP_printk("pages:%ld reason:%s (%d)", __entry->pages, __print_symbolic(__entry->reason, TLB_FLUSH_REASON), __entry->reason) ); #endif /* _TRACE_TLB_H */ /* This part must be outside protection */ #include td>Tobias Klauser
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authorNicolai Stange <nicstange@gmail.com>2016-05-05 17:38:03 -0400
committerTheodore Ts'o <tytso@mit.edu>2016-05-05 17:38:03 -0400
commitb5cb316cdf3a3f5f6125412b0f6065185240cfdc (patch)
tree73741ce9475852c6dc786ea151f09b9fb1e56783
parent74177f55b70e2f2be770dd28684dd6d17106a4ba (diff)
ext4: address UBSAN warning in mb_find_order_for_block()
Currently, in mb_find_order_for_block(), there's a loop like the following: while (order <= e4b->bd_blkbits + 1) { ... bb += 1 << (e4b->bd_blkbits - order); } Note that the updated bb is used in the loop's next iteration only. However, at the last iteration, that is at order == e4b->bd_blkbits + 1, the shift count becomes negative (c.f. C99 6.5.7(3)) and UBSAN reports UBSAN: Undefined behaviour in fs/ext4/mballoc.c:1281:11 shift exponent -1 is negative [...] Call Trace: [<ffffffff818c4d35>] dump_stack+0xbc/0x117 [<ffffffff818c4c79>] ? _atomic_dec_and_lock+0x169/0x169 [<ffffffff819411bb>] ubsan_epilogue+0xd/0x4e [<ffffffff81941cbc>] __ubsan_handle_shift_out_of_bounds+0x1fb/0x254 [<ffffffff81941ac1>] ? __ubsan_handle_load_invalid_value+0x158/0x158 [<ffffffff816e93a0>] ? ext4_mb_generate_from_pa+0x590/0x590 [<ffffffff816502c8>] ? ext4_read_block_bitmap_nowait+0x598/0xe80 [<ffffffff816e7b7e>] mb_find_order_for_block+0x1ce/0x240 [...] Unless compilers start to do some fancy transformations (which at least GCC 6.0.0 doesn't currently do), the issue is of cosmetic nature only: the such calculated value of bb is never used again. Silence UBSAN by introducing another variable, bb_incr, holding the next increment to apply to bb and adjust that one by right shifting it by one position per loop iteration. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=114701 Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=112161 Cc: stable@vger.kernel.org Signed-off-by: Nicolai Stange <nicstange@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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