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linux/arch/arc/mm/cache_arc700.c

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/*
* ARC700 VIPT Cache Management
*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* vineetg: May 2011: for Non-aliasing VIPT D-cache following can be NOPs
* -flush_cache_dup_mm (fork)
* -likewise for flush_cache_mm (exit/execve)
* -likewise for flush_cache_range,flush_cache_page (munmap, exit, COW-break)
*
* vineetg: Apr 2011
* -Now that MMU can support larger pg sz (16K), the determiniation of
* aliasing shd not be based on assumption of 8k pg
*
* vineetg: Mar 2011
* -optimised version of flush_icache_range( ) for making I/D coherent
* when vaddr is available (agnostic of num of aliases)
*
* vineetg: Mar 2011
* -Added documentation about I-cache aliasing on ARC700 and the way it
* was handled up until MMU V2.
* -Spotted a three year old bug when killing the 4 aliases, which needs
* bottom 2 bits, so we need to do paddr | {0x00, 0x01, 0x02, 0x03}
* instead of paddr | {0x00, 0x01, 0x10, 0x11}
* (Rajesh you owe me one now)
*
* vineetg: Dec 2010
* -Off-by-one error when computing num_of_lines to flush
* This broke signal handling with bionic which uses synthetic sigret stub
*
* vineetg: Mar 2010
* -GCC can't generate ZOL for core cache flush loops.
* Conv them into iterations based as opposed to while (start < end) types
*
* Vineetg: July 2009
* -In I-cache flush routine we used to chk for aliasing for every line INV.
* Instead now we setup routines per cache geometry and invoke them
* via function pointers.
*
* Vineetg: Jan 2009
* -Cache Line flush routines used to flush an extra line beyond end addr
* because check was while (end >= start) instead of (end > start)
* =Some call sites had to work around by doing -1, -4 etc to end param
* =Some callers didnt care. This was spec bad in case of INV routines
* which would discard valid data (cause of the horrible ext2 bug
* in ARC IDE driver)
*
* vineetg: June 11th 2008: Fixed flush_icache_range( )
* -Since ARC700 caches are not coherent (I$ doesnt snoop D$) both need
* to be flushed, which it was not doing.
* -load_module( ) passes vmalloc addr (Kernel Virtual Addr) to the API,
* however ARC cache maintenance OPs require PHY addr. Thus need to do
* vmalloc_to_phy.
* -Also added optimisation there, that for range > PAGE SIZE we flush the
* entire cache in one shot rather than line by line. For e.g. a module
* with Code sz 600k, old code flushed 600k worth of cache (line-by-line),
* while cache is only 16 or 32k.
*/
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/cache.h>
#include <linux/mmu_context.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <linux/pagemap.h>
#include <asm/cacheflush.h>
#include <asm/cachectl.h>
#include <asm/setup.h>
/* Instruction cache related Auxiliary registers */
#define ARC_REG_IC_BCR 0x77 /* Build Config reg */
#define ARC_REG_IC_IVIC 0x10
#define ARC_REG_IC_CTRL 0x11
#define ARC_REG_IC_IVIL 0x19
#if (CONFIG_ARC_MMU_VER > 2)
#define ARC_REG_IC_PTAG 0x1E
#endif
/* Bit val in IC_CTRL */
#define IC_CTRL_CACHE_DISABLE 0x1
/* Data cache related Auxiliary registers */
#define ARC_REG_DC_BCR 0x72 /* Build Config reg */
#define ARC_REG_DC_IVDC 0x47
#define ARC_REG_DC_CTRL 0x48
#define ARC_REG_DC_IVDL 0x4A
#define ARC_REG_DC_FLSH 0x4B
#define ARC_REG_DC_FLDL 0x4C
#if (CONFIG_ARC_MMU_VER > 2)
#define ARC_REG_DC_PTAG 0x5C
#endif
/* Bit val in DC_CTRL */
#define DC_CTRL_INV_MODE_FLUSH 0x40
#define DC_CTRL_FLUSH_STATUS 0x100
char *arc_cache_mumbojumbo(int cpu_id, char *buf, int len)
{
int n = 0;
unsigned int c = smp_processor_id();
#define PR_CACHE(p, enb, str) \
{ \
if (!(p)->ver) \
n += scnprintf(buf + n, len - n, str"\t\t: N/A\n"); \
else \
n += scnprintf(buf + n, len - n, \
str"\t\t: (%uK) VIPT, %dway set-asc, %ub Line %s\n", \
TO_KB((p)->sz), (p)->assoc, (p)->line_len, \
enb ? "" : "DISABLED (kernel-build)"); \
}
PR_CACHE(&cpuinfo_arc700[c].icache, IS_ENABLED(CONFIG_ARC_HAS_ICACHE),
"I-Cache");
PR_CACHE(&cpuinfo_arc700[c].dcache, IS_ENABLED(CONFIG_ARC_HAS_DCACHE),
"D-Cache");
return buf;
}
/*
* Read the Cache Build Confuration Registers, Decode them and save into
* the cpuinfo structure for later use.
* No Validation done here, simply read/convert the BCRs
*/
void read_decode_cache_bcr(void)
{
struct cpuinfo_arc_cache *p_ic, *p_dc;
unsigned int cpu = smp_processor_id();
struct bcr_cache {
#ifdef CONFIG_CPU_BIG_ENDIAN
unsigned int pad:12, line_len:4, sz:4, config:4, ver:8;
#else
unsigned int ver:8, config:4, sz:4, line_len:4, pad:12;
#endif
} ibcr, dbcr;
p_ic = &cpuinfo_arc700[cpu].icache;
READ_BCR(ARC_REG_IC_BCR, ibcr);
BUG_ON(ibcr.config != 3);
p_ic->assoc = 2; /* Fixed to 2w set assoc */
p_ic->line_len = 8 << ibcr.line_len;
p_ic->sz = 0x200 << ibcr.sz;
p_ic->ver = ibcr.ver;
p_dc = &cpuinfo_arc700[cpu].dcache;
READ_BCR(ARC_REG_DC_BCR, dbcr);
BUG_ON(dbcr.config != 2);
p_dc->assoc = 4; /* Fixed to 4w set assoc */
p_dc->line_len = 16 << dbcr.line_len;
p_dc->sz = 0x200 << dbcr.sz;
p_dc->ver = dbcr.ver;
}
/*
* 1. Validate the Cache Geomtery (compile time config matches hardware)
* 2. If I-cache suffers from aliasing, setup work arounds (difft flush rtn)
* (aliasing D-cache configurations are not supported YET)
* 3. Enable the Caches, setup default flush mode for D-Cache
* 3. Calculate the SHMLBA used by user space
*/
void arc_cache_init(void)
{
unsigned int cpu = smp_processor_id();
struct cpuinfo_arc_cache *ic = &cpuinfo_arc700[cpu].icache;
struct cpuinfo_arc_cache *dc = &cpuinfo_arc700[cpu].dcache;
unsigned int dcache_does_alias, temp;
char str[256];
printk(arc_cache_mumbojumbo(0, str, sizeof(str)));
if (!ic->ver)
goto chk_dc;
#ifdef CONFIG_ARC_HAS_ICACHE
/* 1. Confirm some of I-cache params which Linux assumes */
if (ic->line_len != L1_CACHE_BYTES)
panic("Cache H/W doesn't match kernel Config");
if (ic->ver != CONFIG_ARC_MMU_VER)
panic("Cache ver doesn't match MMU ver\n");
#endif
/* Enable/disable I-Cache */
temp = read_aux_reg(ARC_REG_IC_CTRL);
#ifdef CONFIG_ARC_HAS_ICACHE
temp &= ~IC_CTRL_CACHE_DISABLE;
#else
temp |= IC_CTRL_CACHE_DISABLE;
#endif
write_aux_reg(ARC_REG_IC_CTRL, temp);
chk_dc:
if (!dc->ver)
return;
#ifdef CONFIG_ARC_HAS_DCACHE
if (dc->line_len != L1_CACHE_BYTES)
panic("Cache H/W doesn't match kernel Config");
/* check for D-Cache aliasing */
dcache_does_alias = (dc->sz / dc->assoc) > PAGE_SIZE;
if (dcache_does_alias && !cache_is_vipt_aliasing())
panic("Enable CONFIG_ARC_CACHE_VIPT_ALIASING\n");
else if (!dcache_does_alias && cache_is_vipt_aliasing())
panic("Don't need CONFIG_ARC_CACHE_VIPT_ALIASING\n");
#endif
/* Set the default Invalidate Mode to "simpy discard dirty lines"
* as this is more frequent then flush before invalidate
* Ofcourse we toggle this default behviour when desired
*/
temp = read_aux_reg(ARC_REG_DC_CTRL);
temp &= ~DC_CTRL_INV_MODE_FLUSH;
#ifdef CONFIG_ARC_HAS_DCACHE
/* Enable D-Cache: Clear Bit 0 */
write_aux_reg(ARC_REG_DC_CTRL, temp & ~IC_CTRL_CACHE_DISABLE);
#else
/* Flush D cache */
write_aux_reg(ARC_REG_DC_FLSH, 0x1);
/* Disable D cache */
write_aux_reg(ARC_REG_DC_CTRL, temp | IC_CTRL_CACHE_DISABLE);
#endif
return;
}
#define OP_INV 0x1
#define OP_FLUSH 0x2
#define OP_FLUSH_N_INV 0x3
#define OP_INV_IC 0x4
/*
* Common Helper for Line Operations on {I,D}-Cache
*/
static inline void __cache_line_loop(unsigned long paddr, unsigned long vaddr,
unsigned long sz, const int cacheop)
{
unsigned int aux_cmd, aux_tag;
int num_lines;
const int full_page_op = __builtin_constant_p(sz) && sz == PAGE_SIZE;
if (cacheop == OP_INV_IC) {
aux_cmd = ARC_REG_IC_IVIL;
aux_tag = ARC_REG_IC_PTAG;
}
else {
/* d$ cmd: INV (discard or wback-n-discard) OR FLUSH (wback) */
aux_cmd = cacheop & OP_INV ? ARC_REG_DC_IVDL : ARC_REG_DC_FLDL;
aux_tag = ARC_REG_DC_PTAG;
}
/* Ensure we properly floor/ceil the non-line aligned/sized requests
* and have @paddr - aligned to cache line and integral @num_lines.
* This however can be avoided for page sized since:
* -@paddr will be cache-line aligned already (being page aligned)
* -@sz will be integral multiple of line size (being page sized).
*/
if (!full_page_op) {
sz += paddr & ~CACHE_LINE_MASK;
paddr &= CACHE_LINE_MASK;
vaddr &= CACHE_LINE_MASK;
}
num_lines = DIV_ROUND_UP(sz, L1_CACHE_BYTES);
#if (CONFIG_ARC_MMU_VER <= 2)
/* MMUv2 and before: paddr contains stuffed vaddrs bits */
paddr |= (vaddr >> PAGE_SHIFT) & 0x1F;
#else
/* if V-P const for loop, PTAG can be written once outside loop */
if (full_page_op)
write_aux_reg(ARC_REG_DC_PTAG, paddr);
#endif
while (num_lines-- > 0) {
#if (CONFIG_ARC_MMU_VER > 2)
/* MMUv3, cache ops require paddr seperately */
if (!full_page_op) {
write_aux_reg(aux_tag, paddr);
paddr += L1_CACHE_BYTES;
}
write_aux_reg(aux_cmd, vaddr);
vaddr += L1_CACHE_BYTES;
#else
write_aux_reg(aux, paddr);
paddr += L1_CACHE_BYTES;
#endif
}
}
#ifdef CONFIG_ARC_HAS_DCACHE
/***************************************************************
* Machine specific helpers for Entire D-Cache or Per Line ops
*/
static inline void wait_for_flush(void)
{
while (read_aux_reg(ARC_REG_DC_CTRL) & DC_CTRL_FLUSH_STATUS)
;
}
/*
* Operation on Entire D-Cache
* @cacheop = {OP_INV, OP_FLUSH, OP_FLUSH_N_INV}
* Note that constant propagation ensures all the checks are gone
* in generated code
*/
static inline void __dc_entire_op(const int cacheop)
{
unsigned int tmp = tmp;
int aux;
if (cacheop == OP_FLUSH_N_INV) {
/* Dcache provides 2 cmd: FLUSH or INV
* INV inturn has sub-modes: DISCARD or FLUSH-BEFORE
* flush-n-inv is achieved by INV cmd but with IM=1
* Default INV sub-mode is DISCARD, which needs to be toggled
*/
tmp = read_aux_reg(ARC_REG_DC_CTRL);
write_aux_reg(ARC_REG_DC_CTRL, tmp | DC_CTRL_INV_MODE_FLUSH);
}
if (cacheop & OP_INV) /* Inv or flush-n-inv use same cmd reg */
aux = ARC_REG_DC_IVDC;
else
aux = ARC_REG_DC_FLSH;
write_aux_reg(aux, 0x1);
if (cacheop & OP_FLUSH) /* flush / flush-n-inv both wait */
wait_for_flush();
/* Switch back the DISCARD ONLY Invalidate mode */
if (cacheop == OP_FLUSH_N_INV)
write_aux_reg(ARC_REG_DC_CTRL, tmp & ~DC_CTRL_INV_MODE_FLUSH);
}
/* For kernel mappings cache operation: index is same as paddr */
#define __dc_line_op_k(p, sz, op) __dc_line_op(p, p, sz, op)
/*
* D-Cache : Per Line INV (discard or wback+discard) or FLUSH (wback)
*/
static inline void __dc_line_op(unsigned long paddr, unsigned long vaddr,
unsigned long sz, const int cacheop)
{
unsigned long flags, tmp = tmp;
local_irq_save(flags);
if (cacheop == OP_FLUSH_N_INV) {
/*
* Dcache provides 2 cmd: FLUSH or INV
* INV inturn has sub-modes: DISCARD or FLUSH-BEFORE
* flush-n-inv is achieved by INV cmd but with IM=1
* Default INV sub-mode is DISCARD, which needs to be toggled
*/
tmp = read_aux_reg(ARC_REG_DC_CTRL);
write_aux_reg(ARC_REG_DC_CTRL, tmp | DC_CTRL_INV_MODE_FLUSH);
}
__cache_line_loop(paddr, vaddr, sz, cacheop);
if (cacheop & OP_FLUSH) /* flush / flush-n-inv both wait */
wait_for_flush();
/* Switch back the DISCARD ONLY Invalidate mode */
if (cacheop == OP_FLUSH_N_INV)
write_aux_reg(ARC_REG_DC_CTRL, tmp & ~DC_CTRL_INV_MODE_FLUSH);
local_irq_restore(flags);
}
#else
#define __dc_entire_op(cacheop)
#define __dc_line_op(paddr, vaddr, sz, cacheop)
#define __dc_line_op_k(paddr, sz, cacheop)
#endif /* CONFIG_ARC_HAS_DCACHE */
#ifdef CONFIG_ARC_HAS_ICACHE
/*
* I-Cache Aliasing in ARC700 VIPT caches
*
* ARC VIPT I-cache uses vaddr to index into cache and paddr to match the tag.
* The orig Cache Management Module "CDU" only required paddr to invalidate a
* certain line since it sufficed as index in Non-Aliasing VIPT cache-geometry.
* Infact for distinct V1,V2,P: all of {V1-P},{V2-P},{P-P} would end up fetching
* the exact same line.
*
* However for larger Caches (way-size > page-size) - i.e. in Aliasing config,
* paddr alone could not be used to correctly index the cache.
*
* ------------------
* MMU v1/v2 (Fixed Page Size 8k)
* ------------------
* The solution was to provide CDU with these additonal vaddr bits. These
* would be bits [x:13], x would depend on cache-geometry, 13 comes from
* standard page size of 8k.
* H/w folks chose [17:13] to be a future safe range, and moreso these 5 bits
* of vaddr could easily be "stuffed" in the paddr as bits [4:0] since the
* orig 5 bits of paddr were anyways ignored by CDU line ops, as they
* represent the offset within cache-line. The adv of using this "clumsy"
* interface for additional info was no new reg was needed in CDU programming
* model.
*
* 17:13 represented the max num of bits passable, actual bits needed were
* fewer, based on the num-of-aliases possible.
* -for 2 alias possibility, only bit 13 needed (32K cache)
* -for 4 alias possibility, bits 14:13 needed (64K cache)
*
* ------------------
* MMU v3
* ------------------
* This ver of MMU supports variable page sizes (1k-16k): although Linux will
* only support 8k (default), 16k and 4k.
* However from hardware perspective, smaller page sizes aggrevate aliasing
* meaning more vaddr bits needed to disambiguate the cache-line-op ;
* the existing scheme of piggybacking won't work for certain configurations.
* Two new registers IC_PTAG and DC_PTAG inttoduced.
* "tag" bits are provided in PTAG, index bits in existing IVIL/IVDL/FLDL regs
*/
/***********************************************************
* Machine specific helper for per line I-Cache invalidate.
*/
static void __ic_line_inv_vaddr(unsigned long paddr, unsigned long vaddr,
unsigned long sz)
{
unsigned long flags;
local_irq_save(flags);
__cache_line_loop(paddr, vaddr, sz, OP_INV_IC);
local_irq_restore(flags);
}
static inline void __ic_entire_inv(void)
{
write_aux_reg(ARC_REG_IC_IVIC, 1);
read_aux_reg(ARC_REG_IC_CTRL); /* blocks */
}
#else
#define __ic_entire_inv()
#define __ic_line_inv_vaddr(pstart, vstart, sz)
#endif /* CONFIG_ARC_HAS_ICACHE */
/***********************************************************
* Exported APIs
*/
/*
* Handle cache congruency of kernel and userspace mappings of page when kernel
* writes-to/reads-from
*
* The idea is to defer flushing of kernel mapping after a WRITE, possible if:
* -dcache is NOT aliasing, hence any U/K-mappings of page are congruent
* -U-mapping doesn't exist yet for page (finalised in update_mmu_cache)
* -In SMP, if hardware caches are coherent
*
* There's a corollary case, where kernel READs from a userspace mapped page.
* If the U-mapping is not congruent to to K-mapping, former needs flushing.
*/
void flush_dcache_page(struct page *page)
{
struct address_space *mapping;
if (!cache_is_vipt_aliasing()) {
clear_bit(PG_dc_clean, &page->flags);
return;
}
/* don't handle anon pages here */
mapping = page_mapping(page);
if (!mapping)
return;
/*
* pagecache page, file not yet mapped to userspace
* Make a note that K-mapping is dirty
*/
if (!mapping_mapped(mapping)) {
clear_bit(PG_dc_clean, &page->flags);
} else if (page_mapped(page)) {
/* kernel reading from page with U-mapping */
void *paddr = page_address(page);
unsigned long vaddr = page->index << PAGE_CACHE_SHIFT;
if (addr_not_cache_congruent(paddr, vaddr))
__flush_dcache_page(paddr, vaddr);
}
}
EXPORT_SYMBOL(flush_dcache_page);
void dma_cache_wback_inv(unsigned long start, unsigned long sz)
{
__dc_line_op_k(start, sz, OP_FLUSH_N_INV);
}
EXPORT_SYMBOL(dma_cache_wback_inv);
void dma_cache_inv(unsigned long start, unsigned long sz)
{
__dc_line_op_k(start, sz, OP_INV);
}
EXPORT_SYMBOL(dma_cache_inv);
void dma_cache_wback(unsigned long start, unsigned long sz)
{
__dc_line_op_k(start, sz, OP_FLUSH);
}
EXPORT_SYMBOL(dma_cache_wback);
/*
* This is API for making I/D Caches consistent when modifying
* kernel code (loadable modules, kprobes, kgdb...)
* This is called on insmod, with kernel virtual address for CODE of
* the module. ARC cache maintenance ops require PHY address thus we
* need to convert vmalloc addr to PHY addr
*/
void flush_icache_range(unsigned long kstart, unsigned long kend)
{
unsigned int tot_sz, off, sz;
unsigned long phy, pfn;
/* printk("Kernel Cache Cohenercy: %lx to %lx\n",kstart, kend); */
/* This is not the right API for user virtual address */
if (kstart < TASK_SIZE) {
BUG_ON("Flush icache range for user virtual addr space");
return;
}
/* Shortcut for bigger flush ranges.
* Here we don't care if this was kernel virtual or phy addr
*/
tot_sz = kend - kstart;
if (tot_sz > PAGE_SIZE) {
flush_cache_all();
return;
}
/* Case: Kernel Phy addr (0x8000_0000 onwards) */
if (likely(kstart > PAGE_OFFSET)) {
/*
* The 2nd arg despite being paddr will be used to index icache
* This is OK since no alternate virtual mappings will exist
* given the callers for this case: kprobe/kgdb in built-in
* kernel code only.
*/
__sync_icache_dcache(kstart, kstart, kend - kstart);
return;
}
/*
* Case: Kernel Vaddr (0x7000_0000 to 0x7fff_ffff)
* (1) ARC Cache Maintenance ops only take Phy addr, hence special
* handling of kernel vaddr.
*
* (2) Despite @tot_sz being < PAGE_SIZE (bigger cases handled already),
* it still needs to handle a 2 page scenario, where the range
* straddles across 2 virtual pages and hence need for loop
*/
while (tot_sz > 0) {
off = kstart % PAGE_SIZE;
pfn = vmalloc_to_pfn((void *)kstart);
phy = (pfn << PAGE_SHIFT) + off;
sz = min_t(unsigned int, tot_sz, PAGE_SIZE - off);
__sync_icache_dcache(phy, kstart, sz);
kstart += sz;
tot_sz -= sz;
}
}
/*
* General purpose helper to make I and D cache lines consistent.
* @paddr is phy addr of region
* @vaddr is typically user vaddr (breakpoint) or kernel vaddr (vmalloc)
* However in one instance, when called by kprobe (for a breakpt in
* builtin kernel code) @vaddr will be paddr only, meaning CDU operation will
* use a paddr to index the cache (despite VIPT). This is fine since since a
* builtin kernel page will not have any virtual mappings.
* kprobe on loadable module will be kernel vaddr.
*/
void __sync_icache_dcache(unsigned long paddr, unsigned long vaddr, int len)
{
unsigned long flags;
local_irq_save(flags);
__ic_line_inv_vaddr(paddr, vaddr, len);
__dc_line_op(paddr, vaddr, len, OP_FLUSH_N_INV);
local_irq_restore(flags);
}
/* wrapper to compile time eliminate alignment checks in flush loop */
void __inv_icache_page(unsigned long paddr, unsigned long vaddr)
{
__ic_line_inv_vaddr(paddr, vaddr, PAGE_SIZE);
}
/*
* wrapper to clearout kernel or userspace mappings of a page
* For kernel mappings @vaddr == @paddr
*/
void ___flush_dcache_page(unsigned long paddr, unsigned long vaddr)
{
__dc_line_op(paddr, vaddr & PAGE_MASK, PAGE_SIZE, OP_FLUSH_N_INV);
}
noinline void flush_cache_all(void)
{
unsigned long flags;
local_irq_save(flags);
__ic_entire_inv();
__dc_entire_op(OP_FLUSH_N_INV);
local_irq_restore(flags);
}
#ifdef CONFIG_ARC_CACHE_VIPT_ALIASING
void flush_cache_mm(struct mm_struct *mm)
{
flush_cache_all();
}
void flush_cache_page(struct vm_area_struct *vma, unsigned long u_vaddr,
unsigned long pfn)
{
unsigned int paddr = pfn << PAGE_SHIFT;
u_vaddr &= PAGE_MASK;
___flush_dcache_page(paddr, u_vaddr);
if (vma->vm_flags & VM_EXEC)
__inv_icache_page(paddr, u_vaddr);
}
void flush_cache_range(struct vm_area_struct *vma, unsigned long start,
unsigned long end)
{
flush_cache_all();
}
void flush_anon_page(struct vm_area_struct *vma, struct page *page,
unsigned long u_vaddr)
{
/* TBD: do we really need to clear the kernel mapping */
__flush_dcache_page(page_address(page), u_vaddr);
__flush_dcache_page(page_address(page), page_address(page));
}
#endif
void copy_user_highpage(struct page *to, struct page *from,
unsigned long u_vaddr, struct vm_area_struct *vma)
{
void *kfrom = page_address(from);
void *kto = page_address(to);
int clean_src_k_mappings = 0;
/*
* If SRC page was already mapped in userspace AND it's U-mapping is
* not congruent with K-mapping, sync former to physical page so that
* K-mapping in memcpy below, sees the right data
*
* Note that while @u_vaddr refers to DST page's userspace vaddr, it is
* equally valid for SRC page as well
*/
if (page_mapped(from) && addr_not_cache_congruent(kfrom, u_vaddr)) {
__flush_dcache_page(kfrom, u_vaddr);
clean_src_k_mappings = 1;
}
copy_page(kto, kfrom);
/*
* Mark DST page K-mapping as dirty for a later finalization by
* update_mmu_cache(). Although the finalization could have been done
* here as well (given that both vaddr/paddr are available).
* But update_mmu_cache() already has code to do that for other
* non copied user pages (e.g. read faults which wire in pagecache page
* directly).
*/
clear_bit(PG_dc_clean, &to->flags);
/*
* if SRC was already usermapped and non-congruent to kernel mapping
* sync the kernel mapping back to physical page
*/
if (clean_src_k_mappings) {
__flush_dcache_page(kfrom, kfrom);
set_bit(PG_dc_clean, &from->flags);
} else {
clear_bit(PG_dc_clean, &from->flags);
}
}
void clear_user_page(void *to, unsigned long u_vaddr, struct page *page)
{
clear_page(to);
clear_bit(PG_dc_clean, &page->flags);
}
/**********************************************************************
* Explicit Cache flush request from user space via syscall
* Needed for JITs which generate code on the fly
*/
SYSCALL_DEFINE3(cacheflush, uint32_t, start, uint32_t, sz, uint32_t, flags)
{
/* TBD: optimize this */
flush_cache_all();
return 0;
}
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