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88776c0e70
Qemu for PARISC reported on a 32bit SMP parisc kernel strange failures about "Not-handled unaligned insn 0x0e8011d6 and 0x0c2011c9." Those opcodes evaluate to the ldcw() assembly instruction which requires (on 32bit) an alignment of 16 bytes to ensure atomicity. As it turns out, qemu is correct and in our assembly code in entry.S and pacache.S we don't pay attention to the required alignment. This patch fixes the problem by aligning the lock offset in assembly code in the same manner as we do in our C-code. Signed-off-by: Helge Deller <deller@gmx.de> Cc: <stable@vger.kernel.org> # v4.0+
59 lines
2.2 KiB
C
59 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __PARISC_LDCW_H
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#define __PARISC_LDCW_H
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#ifndef CONFIG_PA20
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/* Because kmalloc only guarantees 8-byte alignment for kmalloc'd data,
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and GCC only guarantees 8-byte alignment for stack locals, we can't
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be assured of 16-byte alignment for atomic lock data even if we
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specify "__attribute ((aligned(16)))" in the type declaration. So,
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we use a struct containing an array of four ints for the atomic lock
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type and dynamically select the 16-byte aligned int from the array
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for the semaphore. */
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#define __PA_LDCW_ALIGNMENT 16
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#define __PA_LDCW_ALIGN_ORDER 4
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#define __ldcw_align(a) ({ \
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unsigned long __ret = (unsigned long) &(a)->lock[0]; \
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__ret = (__ret + __PA_LDCW_ALIGNMENT - 1) \
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& ~(__PA_LDCW_ALIGNMENT - 1); \
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(volatile unsigned int *) __ret; \
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})
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#define __LDCW "ldcw"
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#else /*CONFIG_PA20*/
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/* From: "Jim Hull" <jim.hull of hp.com>
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I've attached a summary of the change, but basically, for PA 2.0, as
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long as the ",CO" (coherent operation) completer is specified, then the
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16-byte alignment requirement for ldcw and ldcd is relaxed, and instead
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they only require "natural" alignment (4-byte for ldcw, 8-byte for
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ldcd). */
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#define __PA_LDCW_ALIGNMENT 4
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#define __PA_LDCW_ALIGN_ORDER 2
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#define __ldcw_align(a) (&(a)->slock)
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#define __LDCW "ldcw,co"
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#endif /*!CONFIG_PA20*/
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/* LDCW, the only atomic read-write operation PA-RISC has. *sigh*.
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We don't explicitly expose that "*a" may be written as reload
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fails to find a register in class R1_REGS when "a" needs to be
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reloaded when generating 64-bit PIC code. Instead, we clobber
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memory to indicate to the compiler that the assembly code reads
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or writes to items other than those listed in the input and output
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operands. This may pessimize the code somewhat but __ldcw is
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usually used within code blocks surrounded by memory barriers. */
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#define __ldcw(a) ({ \
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unsigned __ret; \
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__asm__ __volatile__(__LDCW " 0(%1),%0" \
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: "=r" (__ret) : "r" (a) : "memory"); \
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__ret; \
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})
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#ifdef CONFIG_SMP
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# define __lock_aligned __attribute__((__section__(".data..lock_aligned")))
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#endif
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#endif /* __PARISC_LDCW_H */
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