linux-dev/arch/powerpc/kernel/misc_32.S, branch linus/master

powerpc: Avoid link stack corruption in misc asm functions

2021-08-25T03:35:47Z

bl;mflr is used at several places to get code position. Use bcl 20,31,+4 instead of bl in order to preserve link stack. See commit c974809a26a1 ("powerpc/vdso: Avoid link stack corruption in __get_datapage()") for details. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/c6eabb4fb6c156f75d56dcbcc6f243e5ac0fba42.1629791763.git.christophe.leroy@csgroup.eu

powerpc/bug: Provide better flexibility to WARN_ON/__WARN_FLAGS() with asm goto

2021-08-15T03:49:24Z

Using asm goto in __WARN_FLAGS() and WARN_ON() allows more flexibility to GCC. For that add an entry to the exception table so that program_check_exception() knowns where to resume execution after a WARNING. Here are two exemples. The first one is done on PPC32 (which benefits from the previous patch), the second is on PPC64. unsigned long test(struct pt_regs *regs) { int ret; WARN_ON(regs->msr & MSR_PR); return regs->gpr[3]; } unsigned long test9w(unsigned long a, unsigned long b) { if (WARN_ON(!b)) return 0; return a / b; } Before the patch: 000003a8 : 3a8: 81 23 00 84 lwz r9,132(r3) 3ac: 71 29 40 00 andi. r9,r9,16384 3b0: 40 82 00 0c bne 3bc 3b4: 80 63 00 0c lwz r3,12(r3) 3b8: 4e 80 00 20 blr 3bc: 0f e0 00 00 twui r0,0 3c0: 80 63 00 0c lwz r3,12(r3) 3c4: 4e 80 00 20 blr 0000000000000bf0 <.test9w>: bf0: 7c 89 00 74 cntlzd r9,r4 bf4: 79 29 d1 82 rldicl r9,r9,58,6 bf8: 0b 09 00 00 tdnei r9,0 bfc: 2c 24 00 00 cmpdi r4,0 c00: 41 82 00 0c beq c0c <.test9w+0x1c> c04: 7c 63 23 92 divdu r3,r3,r4 c08: 4e 80 00 20 blr c0c: 38 60 00 00 li r3,0 c10: 4e 80 00 20 blr After the patch: 000003a8 : 3a8: 81 23 00 84 lwz r9,132(r3) 3ac: 71 29 40 00 andi. r9,r9,16384 3b0: 40 82 00 0c bne 3bc 3b4: 80 63 00 0c lwz r3,12(r3) 3b8: 4e 80 00 20 blr 3bc: 0f e0 00 00 twui r0,0 0000000000000c50 <.test9w>: c50: 7c 89 00 74 cntlzd r9,r4 c54: 79 29 d1 82 rldicl r9,r9,58,6 c58: 0b 09 00 00 tdnei r9,0 c5c: 7c 63 23 92 divdu r3,r3,r4 c60: 4e 80 00 20 blr c70: 38 60 00 00 li r3,0 c74: 4e 80 00 20 blr In the first exemple, we see GCC doesn't need to duplicate what happens after the trap. In the second exemple, we see that GCC doesn't need to emit a test and a branch in the likely path in addition to the trap. We've got some WARN_ON() in .softirqentry.text section so it needs to be added in the OTHER_TEXT_SECTIONS in modpost.c Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/389962b1b702e3c78d169e59bcfac56282889173.1618331882.git.christophe.leroy@csgroup.eu

powerpc/32: Remove __main()

2021-06-16T14:09:10Z

Comment says that __main() is there to make GCC happy. It's been there since the implementation of ppc arch in Linux 1.3.45. ppc32 is the only architecture having that. Even ppc64 doesn't have it. Seems like GCC is still happy without it. Drop it for good. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/d01028f8166b98584eec536b52f14c5e3f98ff6b.1623172922.git.christophe.leroy@csgroup.eu

powerpc/irq: Inline call_do_irq() and call_do_softirq()

2021-03-29T02:22:17Z

call_do_irq() and call_do_softirq() are simple enough to be worth inlining. Inlining them avoids an mflr/mtlr pair plus a save/reload on stack. This is inspired from S390 arch. Several other arches do more or less the same. The way sparc arch does seems odd thought. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210320122227.345427-1-mpe@ellerman.id.au

powerpc/32: Remove ksp_limit

2021-03-29T02:22:05Z

ksp_limit is there to help detect stack overflows. That is specific to ppc32 as it was removed from ppc64 in commit cbc9565ee826 ("powerpc: Remove ksp_limit on ppc64"). There are other means for detecting stack overflows. As ppc64 has proven to not need it, ppc32 should be able to do without it too. Lets remove it and simplify exception handling. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/d789c3385b22e07bedc997613c0d26074cb513e7.1615552866.git.christophe.leroy@csgroup.eu

powerpc: Rewrite FSL_BOOKE flush_cache_instruction() in C

2020-09-02T01:00:21Z

Nothing prevents flush_cache_instruction() from being writen in C. Do it to improve readability and maintainability. This function is only use by low level callers, it is not intended to be used by module. Don't export it. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/f989eff8296800c427622c0985384148404e4f0b.1597384512.git.christophe.leroy@csgroup.eu

powerpc: Rewrite 4xx flush_cache_instruction() in C

2020-09-02T01:00:21Z

Nothing prevents flush_cache_instruction() from being writen in C. Do it to improve readability and maintainability. This function is very small and isn't called from assembly, make it static inline in asm/cacheflush.h Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/93d93fc69b4b3ad3ceba2fc0756333c0c0245bb7.1597384512.git.christophe.leroy@csgroup.eu

powerpc: Remove flush_instruction_cache for book3s/32

2020-09-02T01:00:21Z

The only callers of flush_instruction_cache() are: arch/powerpc/kernel/swsusp_booke.S: bl flush_instruction_cache arch/powerpc/mm/nohash/40x.c: flush_instruction_cache(); arch/powerpc/mm/nohash/44x.c: flush_instruction_cache(); arch/powerpc/mm/nohash/fsl_booke.c: flush_instruction_cache(); arch/powerpc/platforms/44x/machine_check.c: flush_instruction_cache(); arch/powerpc/platforms/44x/machine_check.c: flush_instruction_cache(); This function is not used by book3s/32, drop it. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/50098f49877cea0f46730a9df82dcabf84160e4b.1597384512.git.christophe.leroy@csgroup.eu

powerpc: Drop _nmask_and_or_msr()

2020-09-02T01:00:20Z

_nmask_and_or_msr() is only used at two places to set MSR_IP. The SYNC is unnecessary as the users are not PowerPC 601. Can be easily writen in C. Do it, and drop _nmask_and_or_msr() Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/c2d2b8dfb8dd677026b26dffc8d31070c38a6b89.1597388079.git.christophe.leroy@csgroup.eu

powerpc/32: Blacklist functions running with MMU disabled for kprobe

2020-06-02T10:59:11Z

kprobe does not handle events happening in real mode, all functions running with MMU disabled have to be blacklisted. Signed-off-by: Christophe Leroy Acked-by: Naveen N. Rao Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/3bf57066d05518644dee0840af69d36ab5086729.1585670437.git.christophe.leroy@c-s.fr