Date: Mon, 15 Jan 2018 15:20:49 -0800 From: Nathan Whitehorn <nwhitehorn@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r327950 - in head/sys/powerpc: aim include powerpc ps3 Message-ID: <bb27ba01-8383-6b85-8b2b-65227ff46efc@freebsd.org> In-Reply-To: <20180115175335.GK1684@kib.kiev.ua> References: <20180114170502.GB1684@kib.kiev.ua> <184ba3ee-a9f7-01ed-bb02-1bcba9acc041@freebsd.org> <20180114175211.GD1684@kib.kiev.ua> <b2b1bf30-177b-af30-54ce-f484224bb2ad@freebsd.org> <f4b44b69-7b06-6b5a-c17c-31bd46ca1af0@freebsd.org> <e04bc7a6-fa77-9ca0-2aff-dc29c543c9a1@freebsd.org> <20180115111812.GF1684@kib.kiev.ua> <f6350c61-55d1-9bf7-c4b3-e10fb329a42a@freebsd.org> <20180115170603.GJ1684@kib.kiev.ua> <9e5554d7-6a0c-5910-8cb6-74f98259536f@freebsd.org> <20180115175335.GK1684@kib.kiev.ua>
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This is a multi-part message in MIME format. --------------082F835BD7FFED1A7DEBEEC2 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit On 01/15/18 09:53, Konstantin Belousov wrote: > On Mon, Jan 15, 2018 at 09:32:56AM -0800, Nathan Whitehorn wrote: >> That seems fine to me. I don't think a less-clumsy way that does not >> involve extra indirection is possible. The PHYS_TO_DMAP() returning NULL >> is about the best thing I can come up with from a clumsiness standpoint >> since plenty of code checks for null pointers already, but doesn't >> cleanly handle the rarer case where you want to test for the existence >> of direct maps in general without testing some potemkin address. >> >> My one reservation about PMAP_HAS_DMAP or the like as a selector is that >> it does not encode the full shape of the problem: one could imagine >> having a direct map that only covers a limited range of RAM (I am not >> sure whether the existence of dmaplimit on amd64 implies this can happen >> with non-device memory in real life), for example. These cases are >> currently covered by an assert() in PHYS_TO_DMAP(), whereas having >> PHYS_TO_DMAP() return NULL allows a more flexible signalling and the >> potential for the calling code to do something reasonable to handle the >> error. A single global flag can't convey information at this kind of >> granularity. Is this a reasonable concern? Or am I overthinking things? > IMO it is overreaction. amd64 assumes that all normal memory is covered > by DMAP. It must never fail. See, for instance, the implementation > of the sf bufs for it. > > If device memory not covered by DMAP can exists, it is the driver problem. > For instance, for NVDIMMs I wrote specific mapping code which establishes > kernel mapping for it, when not covered by EFI memory map and correspondingly > not included into DMAP. > Fair enough. Here's a patch with a new flag (DIRECT_MAP_AVAILABLE). I've also retooled the sfbuf code to use this rather than its own flags that mean the same things. The sparc64 part of the patch is untested. -Nathan --------------082F835BD7FFED1A7DEBEEC2 Content-Type: text/x-patch; name="dmap_api.diff" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="dmap_api.diff" Index: amd64/include/vmparam.h =================================================================== --- amd64/include/vmparam.h (revision 328006) +++ amd64/include/vmparam.h (working copy) @@ -190,6 +190,7 @@ * because the result is not actually accessed until later, but the early * vt fb startup needs to be reworked. */ +#define DIRECT_MAP_AVAILABLE 1 #define PHYS_TO_DMAP(x) ({ \ KASSERT(dmaplimit == 0 || (x) < dmaplimit, \ ("physical address %#jx not covered by the DMAP", \ Index: arm64/include/vmparam.h =================================================================== --- arm64/include/vmparam.h (revision 328006) +++ arm64/include/vmparam.h (working copy) @@ -176,6 +176,7 @@ #define VIRT_IN_DMAP(va) ((va) >= DMAP_MIN_ADDRESS && \ (va) < (dmap_max_addr)) +#define DIRECT_MAP_AVAILABLE #define PHYS_TO_DMAP(pa) \ ({ \ KASSERT(PHYS_IN_DMAP(pa), \ Index: dev/efidev/efirt.c =================================================================== --- dev/efidev/efirt.c (revision 328006) +++ dev/efidev/efirt.c (working copy) @@ -115,6 +115,11 @@ return (0); } efi_systbl = (struct efi_systbl *)PHYS_TO_DMAP(efi_systbl_phys); + if (efi_systbl == NULL) { + if (bootverbose) + printf("EFI systbl not mapped in kernel VA\n"); + return (0); + } if (efi_systbl->st_hdr.th_sig != EFI_SYSTBL_SIG) { efi_systbl = NULL; if (bootverbose) Index: kern/subr_sfbuf.c =================================================================== --- kern/subr_sfbuf.c (revision 328006) +++ kern/subr_sfbuf.c (working copy) @@ -88,8 +88,8 @@ vm_offset_t sf_base; int i; -#ifdef SFBUF_OPTIONAL_DIRECT_MAP - if (SFBUF_OPTIONAL_DIRECT_MAP) +#ifdef DIRECT_MAP_AVAILABLE + if (DIRECT_MAP_AVAILABLE) return; #endif @@ -119,8 +119,8 @@ struct sf_buf *sf; int error; -#ifdef SFBUF_OPTIONAL_DIRECT_MAP - if (SFBUF_OPTIONAL_DIRECT_MAP) +#ifdef DIRECT_MAP_AVAILABLE + if (DIRECT_MAP_AVAILABLE) return ((struct sf_buf *)m); #endif @@ -181,8 +181,8 @@ sf_buf_free(struct sf_buf *sf) { -#ifdef SFBUF_OPTIONAL_DIRECT_MAP - if (SFBUF_OPTIONAL_DIRECT_MAP) +#ifdef DIRECT_MAP_AVAILABLE + if (DIRECT_MAP_AVAILABLE) return; #endif @@ -205,8 +205,8 @@ sf_buf_ref(struct sf_buf *sf) { -#ifdef SFBUF_OPTIONAL_DIRECT_MAP - if (SFBUF_OPTIONAL_DIRECT_MAP) +#ifdef DIRECT_MAP_AVAILABLE + if (DIRECT_MAP_AVAILABLE) return; #endif Index: powerpc/include/vmparam.h =================================================================== --- powerpc/include/vmparam.h (revision 328006) +++ powerpc/include/vmparam.h (working copy) @@ -37,6 +37,10 @@ #ifndef _MACHINE_VMPARAM_H_ #define _MACHINE_VMPARAM_H_ +#ifndef LOCORE +#include <machine/md_var.h> +#endif + #define USRSTACK SHAREDPAGE #ifndef MAXTSIZ @@ -236,17 +240,21 @@ */ #define SFBUF #define SFBUF_NOMD -#define SFBUF_OPTIONAL_DIRECT_MAP hw_direct_map -#define SFBUF_PHYS_DMAP(x) (x) /* - * We (usually) have a direct map of all physical memory. All - * uses of this macro must be gated by a check on hw_direct_map! - * The location of the direct map may not be 1:1 in future, so use - * of the macro is recommended; it may also grow an assert that hw_direct_map - * is set. + * We (usually) have a direct map of all physical memory, so provide + * a macro to use to get the kernel VA address for a given PA. Returns + * 0 if the direct map is unavailable. The location of the direct map + * may not be 1:1 in future, so use of the macro is recommended. */ -#define PHYS_TO_DMAP(x) x -#define DMAP_TO_PHYS(x) x - +#ifdef __powerpc64__ +#define DMAP_ADDRESS 0x0000000000000000UL +#else +#define DMAP_ADDRESS 0x00000000UL +#endif + +#define DIRECT_MAP_AVAILABLE (hw_direct_map) +#define PHYS_TO_DMAP(x) (hw_direct_map ? (x | DMAP_ADDRESS) : 0) +#define DMAP_TO_PHYS(x) (hw_direct_map ? (x & ~DMAP_ADDRESS) : 0) + #endif /* _MACHINE_VMPARAM_H_ */ Index: sparc64/include/vmparam.h =================================================================== --- sparc64/include/vmparam.h (revision 328006) +++ sparc64/include/vmparam.h (working copy) @@ -240,10 +240,12 @@ */ #define ZERO_REGION_SIZE PAGE_SIZE +#include <machine/tlb.h> + #define SFBUF #define SFBUF_MAP -#define SFBUF_OPTIONAL_DIRECT_MAP dcache_color_ignore -#include <machine/tlb.h> -#define SFBUF_PHYS_DMAP(x) TLB_PHYS_TO_DIRECT(x) +#define DIRECT_MAP_AVAILABLE dcache_color_ignore +#define PHYS_TO_DMAP(x) (DIRECT_MAP_AVAILABLE ? (TLB_PHYS_TO_DIRECT(x) : 0) + #endif /* !_MACHINE_VMPARAM_H_ */ Index: sys/sf_buf.h =================================================================== --- sys/sf_buf.h (revision 328006) +++ sys/sf_buf.h (working copy) @@ -77,9 +77,6 @@ * that do no invalidate cache on the rest of CPUs. * SFBUF_NOMD This machine doesn't have machine/sf_buf.h * - * SFBUF_OPTIONAL_DIRECT_MAP Value of this define is used as boolean - * variable that tells whether machine is - * capable of direct map or not at runtime. * SFBUF_MAP This machine provides its own sf_buf_map() and * sf_buf_unmap(). * SFBUF_PROCESS_PAGE This machine provides sf_buf_process_page() @@ -109,9 +106,6 @@ #ifndef SFBUF_NOMD #include <machine/sf_buf.h> #endif -#ifdef SFBUF_OPTIONAL_DIRECT_MAP -#include <machine/md_var.h> -#endif #ifdef SFBUF struct sf_buf *sf_buf_alloc(struct vm_page *, int); @@ -121,9 +115,9 @@ static inline vm_offset_t sf_buf_kva(struct sf_buf *sf) { -#ifdef SFBUF_OPTIONAL_DIRECT_MAP - if (SFBUF_OPTIONAL_DIRECT_MAP) - return (SFBUF_PHYS_DMAP(VM_PAGE_TO_PHYS((vm_page_t)sf))); +#ifdef DIRECT_MAP_AVAILABLE + if (DIRECT_MAP_AVAILABLE) + return (PHYS_TO_DMAP(VM_PAGE_TO_PHYS((vm_page_t)sf))); #endif return (sf->kva); @@ -132,8 +126,8 @@ static inline vm_page_t sf_buf_page(struct sf_buf *sf) { -#ifdef SFBUF_OPTIONAL_DIRECT_MAP - if (SFBUF_OPTIONAL_DIRECT_MAP) +#ifdef DIRECT_MAP_AVAILABLE + if (DIRECT_MAP_AVAILABLE) return ((vm_page_t)sf); #endif Index: vm/vm_page.c =================================================================== --- vm/vm_page.c (revision 328006) +++ vm/vm_page.c (working copy) @@ -2937,7 +2937,8 @@ { #if defined(DIAGNOSTIC) && defined(PHYS_TO_DMAP) - if ((m->flags & PG_ZERO) != 0) { + if ((m->flags & PG_ZERO) != 0 && + PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m)) != 0) { uint64_t *p; int i; p = (uint64_t *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m)); --------------082F835BD7FFED1A7DEBEEC2--
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