On Tue, Apr 28, 2015 at 04:46:36PM -0600, Ross Zwisler wrote: > Add kerneldoc comments for pcommit_sfence() describing the purpose of > the pcommit instruction and demonstrating the usage of that instruction. > > Signed-off-by: Ross Zwisler <[email protected]> > Cc: H Peter Anvin <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Borislav Petkov <[email protected]> > ---
Applied, thanks. I added the "Example:" thing because apparently kernel-doc parses that, see below. Doing $ scripts/kernel-doc -html arch/x86/include/asm/special_insns.h > /tmp/doc.html and then looking at doc.html doesn't make me go all full of joy and clap my hands but whatever, it is better than nothing. --- From: Ross Zwisler <[email protected]> Date: Tue, 28 Apr 2015 16:46:36 -0600 Subject: [PATCH] x86/mm: Add kerneldoc comments for pcommit_sfence() Add kerneldoc comments for pcommit_sfence() describing the purpose of the PCOMMIT instruction and demonstrating its usage with an example. Signed-off-by: Ross Zwisler <[email protected]> Cc: H Peter Anvin <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Borislav Petkov <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Borislav Petkov <[email protected]> --- arch/x86/include/asm/special_insns.h | 38 ++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h index aeb4666e0c0a..2270e41b32fd 100644 --- a/arch/x86/include/asm/special_insns.h +++ b/arch/x86/include/asm/special_insns.h @@ -215,6 +215,44 @@ static inline void clwb(volatile void *__p) : [pax] "a" (p)); } +/** + * pcommit_sfence() - persistent commit and fence + * + * The PCOMMIT instruction ensures that data that has been flushed from the + * processor's cache hierarchy with CLWB, CLFLUSHOPT or CLFLUSH is accepted to + * memory and is durable on the DIMM. The primary use case for this is + * persistent memory. + * + * This function shows how to properly use CLWB/CLFLUSHOPT/CLFLUSH and PCOMMIT + * with appropriate fencing. + * + * Example: + * void flush_and_commit_buffer(void *vaddr, unsigned int size) + * { + * unsigned long clflush_mask = boot_cpu_data.x86_clflush_size - 1; + * void *vend = vaddr + size; + * void *p; + * + * for (p = (void *)((unsigned long)vaddr & ~clflush_mask); + * p < vend; p += boot_cpu_data.x86_clflush_size) + * clwb(p); + * + * // SFENCE to order CLWB/CLFLUSHOPT/CLFLUSH cache flushes + * // MFENCE via mb() also works + * wmb(); + * + * // PCOMMIT and the required SFENCE for ordering + * pcommit_sfence(); + * } + * + * After this function completes the data pointed to by 'vaddr' has been + * accepted to memory and will be durable if the 'vaddr' points to persistent + * memory. + * + * PCOMMIT must always be ordered by an MFENCE or SFENCE, so to help simplify + * things we include both the PCOMMIT and the required SFENCE in the + * alternatives generated by pcommit_sfence(). + */ static inline void pcommit_sfence(void) { alternative(ASM_NOP7, -- 2.3.5 -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
