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This fixes another cause of random segfaults and bus errors that may
occur while running perf with the callgraph option.
Critical sections beginning with spin_lock_irqsave() raise the interrupt
level to PIL_NORMAL_MAX (14) and intentionally do not block performance
counter interrupts, which arrive at PIL_NMI (15).
But some sections of code are "super critical" with respect to perf
because the perf_callchain_user() path accesses user space and may cause
TLB activity as well as faults as it unwinds the user stack.
One particular critical section occurs in switch_mm:
spin_lock_irqsave(&mm->context.lock, flags);
...
load_secondary_context(mm);
tsb_context_switch(mm);
...
spin_unlock_irqrestore(&mm->context.lock, flags);
If a perf interrupt arrives in between load_secondary_context() and
tsb_context_switch(), then perf_callchain_user() could execute with
the context ID of one process, but with an active TSB for a different
process. When the user stack is accessed, it is very likely to
incur a TLB miss, since the h/w context ID has been changed. The TLB
will then be reloaded with a translation from the TSB for one process,
but using a context ID for another process. This exposes memory from
one process to another, and since it is a mapping for stack memory,
this usually causes the new process to crash quickly.
This super critical section needs more protection than is provided
by spin_lock_irqsave() since perf interrupts must not be allowed in.
Since __tsb_context_switch already goes through the trouble of
disabling interrupts completely, we fix this by moving the secondary
context load down into this better protected region.
Orabug: 25577560
Signed-off-by: Dave Aldridge <david.j.aldridge@oracle.com>
Signed-off-by: Rob Gardner <rob.gardner@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull sparc updates from David Miller:
1) Move to 4-level page tables on sparc64 and support up to 53-bits of
physical addressing. Kernel static image BSS size reduced by
several megabytes.
2) M6/M7 cpu support, from Allan Pais.
3) Move to sparse IRQs, handle hypervisor TLB call errors more
gracefully, and add T5 perf_event support. From Bob Picco.
4) Recognize cdroms and compute geometry from capacity in virtual disk
driver, also from Allan Pais.
5) Fix memset() return value on sparc32, from Andreas Larsson.
6) Respect gfp flags in dma_alloc_coherent on sparc32, from Daniel
Hellstrom.
7) Fix handling of compound pages in virtual disk driver, from Dwight
Engen.
8) Fix lockdep warnings in LDC layer by moving IRQ requesting to
ldc_alloc() from ldc_bind().
9) Increase boot string length to 1024 bytes, from Dave Kleikamp.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc: (31 commits)
sparc64: Fix lockdep warnings on reboot on Ultra-5
sparc64: Increase size of boot string to 1024 bytes
sparc64: Kill unnecessary tables and increase MAX_BANKS.
sparc64: sparse irq
sparc64: Adjust vmalloc region size based upon available virtual address bits.
sparc64: Increase MAX_PHYS_ADDRESS_BITS to 53.
sparc64: Use kernel page tables for vmemmap.
sparc64: Fix physical memory management regressions with large max_phys_bits.
sparc64: Adjust KTSB assembler to support larger physical addresses.
sparc64: Define VA hole at run time, rather than at compile time.
sparc64: Switch to 4-level page tables.
sparc64: Fix reversed start/end in flush_tlb_kernel_range()
sparc64: Add vio_set_intr() to enable/disable Rx interrupts
vio: fix reuse of vio_dring slot
sunvdc: limit each sg segment to a page
sunvdc: compute vdisk geometry from capacity
sunvdc: add cdrom and v1.1 protocol support
sparc: VIO protocol version 1.6
sparc64: Fix hibernation code refrence to PAGE_OFFSET.
sparc64: Move request_irq() from ldc_bind() to ldc_alloc()
...
The different architectures used their own (and different) declarations:
extern __visible const void __nosave_begin, __nosave_end;
extern const void __nosave_begin, __nosave_end;
extern long __nosave_begin, __nosave_end;
Consolidate them using the first variant in <asm/sections.h>.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We changed PAGE_OFFSET to be a variable rather than a constant,
but this reference here in the hibernate assembler got missed.
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds CONFIG_HIBERNATION support for sparc64
architecture. The suspend function is the same as on another
platforms. The restore function uses Bypass feature of MMU
which allows to make the process more comfortable and plesant.
Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
CC: David Miller <davem@davemloft.net>
CC: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
