diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2018-08-17 11:32:50 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-08-17 11:32:50 -0700 |
commit | 5e2d059b52e397d9ac42f4c4d9d9a841887b5818 (patch) | |
tree | c8cd8fd7187113be33e29fcc75f45a8bbc27e6b2 /arch/powerpc/lib/strlen_32.S | |
parent | d190775206d06397a9309421cac5ba2f2c243521 (diff) | |
parent | a2dc009afa9ae8b92305be7728676562a104cb40 (diff) |
Merge tag 'powerpc-4.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
"Notable changes:
- A fix for a bug in our page table fragment allocator, where a page
table page could be freed and reallocated for something else while
still in use, leading to memory corruption etc. The fix reuses
pt_mm in struct page (x86 only) for a powerpc only refcount.
- Fixes to our pkey support. Several are user-visible changes, but
bring us in to line with x86 behaviour and/or fix outright bugs.
Thanks to Florian Weimer for reporting many of these.
- A series to improve the hvc driver & related OPAL console code,
which have been seen to cause hardlockups at times. The hvc driver
changes in particular have been in linux-next for ~month.
- Increase our MAX_PHYSMEM_BITS to 128TB when SPARSEMEM_VMEMMAP=y.
- Remove Power8 DD1 and Power9 DD1 support, neither chip should be in
use anywhere other than as a paper weight.
- An optimised memcmp implementation using Power7-or-later VMX
instructions
- Support for barrier_nospec on some NXP CPUs.
- Support for flushing the count cache on context switch on some IBM
CPUs (controlled by firmware), as a Spectre v2 mitigation.
- A series to enhance the information we print on unhandled signals
to bring it into line with other arches, including showing the
offending VMA and dumping the instructions around the fault.
Thanks to: Aaro Koskinen, Akshay Adiga, Alastair D'Silva, Alexey
Kardashevskiy, Alexey Spirkov, Alistair Popple, Andrew Donnellan,
Aneesh Kumar K.V, Anju T Sudhakar, Arnd Bergmann, Bartosz Golaszewski,
Benjamin Herrenschmidt, Bharat Bhushan, Bjoern Noetel, Boqun Feng,
Breno Leitao, Bryant G. Ly, Camelia Groza, Christophe Leroy, Christoph
Hellwig, Cyril Bur, Dan Carpenter, Daniel Klamt, Darren Stevens, Dave
Young, David Gibson, Diana Craciun, Finn Thain, Florian Weimer,
Frederic Barrat, Gautham R. Shenoy, Geert Uytterhoeven, Geoff Levand,
Guenter Roeck, Gustavo Romero, Haren Myneni, Hari Bathini, Joel
Stanley, Jonathan Neuschäfer, Kees Cook, Madhavan Srinivasan, Mahesh
Salgaonkar, Markus Elfring, Mathieu Malaterre, Mauro S. M. Rodrigues,
Michael Hanselmann, Michael Neuling, Michael Schmitz, Mukesh Ojha,
Murilo Opsfelder Araujo, Nicholas Piggin, Parth Y Shah, Paul
Mackerras, Paul Menzel, Ram Pai, Randy Dunlap, Rashmica Gupta, Reza
Arbab, Rodrigo R. Galvao, Russell Currey, Sam Bobroff, Scott Wood,
Shilpasri G Bhat, Simon Guo, Souptick Joarder, Stan Johnson, Thiago
Jung Bauermann, Tyrel Datwyler, Vaibhav Jain, Vasant Hegde, Venkat
Rao, zhong jiang"
* tag 'powerpc-4.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (234 commits)
powerpc/mm/book3s/radix: Add mapping statistics
powerpc/uaccess: Enable get_user(u64, *p) on 32-bit
powerpc/mm/hash: Remove unnecessary do { } while(0) loop
powerpc/64s: move machine check SLB flushing to mm/slb.c
powerpc/powernv/idle: Fix build error
powerpc/mm/tlbflush: update the mmu_gather page size while iterating address range
powerpc/mm: remove warning about ‘type’ being set
powerpc/32: Include setup.h header file to fix warnings
powerpc: Move `path` variable inside DEBUG_PROM
powerpc/powermac: Make some functions static
powerpc/powermac: Remove variable x that's never read
cxl: remove a dead branch
powerpc/powermac: Add missing include of header pmac.h
powerpc/kexec: Use common error handling code in setup_new_fdt()
powerpc/xmon: Add address lookup for percpu symbols
powerpc/mm: remove huge_pte_offset_and_shift() prototype
powerpc/lib: Use patch_site to patch copy_32 functions once cache is enabled
powerpc/pseries: Fix endianness while restoring of r3 in MCE handler.
powerpc/fadump: merge adjacent memory ranges to reduce PT_LOAD segements
powerpc/fadump: handle crash memory ranges array index overflow
...
Diffstat (limited to 'arch/powerpc/lib/strlen_32.S')
-rw-r--r-- | arch/powerpc/lib/strlen_32.S | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/arch/powerpc/lib/strlen_32.S b/arch/powerpc/lib/strlen_32.S new file mode 100644 index 000000000000..0a8d3f64d493 --- /dev/null +++ b/arch/powerpc/lib/strlen_32.S @@ -0,0 +1,78 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * strlen() for PPC32 + * + * Copyright (C) 2018 Christophe Leroy CS Systemes d'Information. + * + * Inspired from glibc implementation + */ +#include <asm/ppc_asm.h> +#include <asm/export.h> +#include <asm/cache.h> + + .text + +/* + * Algorithm: + * + * 1) Given a word 'x', we can test to see if it contains any 0 bytes + * by subtracting 0x01010101, and seeing if any of the high bits of each + * byte changed from 0 to 1. This works because the least significant + * 0 byte must have had no incoming carry (otherwise it's not the least + * significant), so it is 0x00 - 0x01 == 0xff. For all other + * byte values, either they have the high bit set initially, or when + * 1 is subtracted you get a value in the range 0x00-0x7f, none of which + * have their high bit set. The expression here is + * (x - 0x01010101) & ~x & 0x80808080), which gives 0x00000000 when + * there were no 0x00 bytes in the word. You get 0x80 in bytes that + * match, but possibly false 0x80 matches in the next more significant + * byte to a true match due to carries. For little-endian this is + * of no consequence since the least significant match is the one + * we're interested in, but big-endian needs method 2 to find which + * byte matches. + * 2) Given a word 'x', we can test to see _which_ byte was zero by + * calculating ~(((x & ~0x80808080) - 0x80808080 - 1) | x | ~0x80808080). + * This produces 0x80 in each byte that was zero, and 0x00 in all + * the other bytes. The '| ~0x80808080' clears the low 7 bits in each + * byte, and the '| x' part ensures that bytes with the high bit set + * produce 0x00. The addition will carry into the high bit of each byte + * iff that byte had one of its low 7 bits set. We can then just see + * which was the most significant bit set and divide by 8 to find how + * many to add to the index. + * This is from the book 'The PowerPC Compiler Writer's Guide', + * by Steve Hoxey, Faraydon Karim, Bill Hay and Hank Warren. + */ + +_GLOBAL(strlen) + andi. r0, r3, 3 + lis r7, 0x0101 + addi r10, r3, -4 + addic r7, r7, 0x0101 /* r7 = 0x01010101 (lomagic) & clear XER[CA] */ + rotlwi r6, r7, 31 /* r6 = 0x80808080 (himagic) */ + bne- 3f + .balign IFETCH_ALIGN_BYTES +1: lwzu r9, 4(r10) +2: subf r8, r7, r9 + and. r8, r8, r6 + beq+ 1b + andc. r8, r8, r9 + beq+ 1b + andc r8, r9, r6 + orc r9, r9, r6 + subfe r8, r6, r8 + nor r8, r8, r9 + cntlzw r8, r8 + subf r3, r3, r10 + srwi r8, r8, 3 + add r3, r3, r8 + blr + + /* Missaligned string: make sure bytes before string are seen not 0 */ +3: xor r10, r10, r0 + orc r8, r8, r8 + lwzu r9, 4(r10) + slwi r0, r0, 3 + srw r8, r8, r0 + orc r9, r9, r8 + b 2b +EXPORT_SYMBOL(strlen) |