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Mon, 08 Jan 2024 01:47:24 -0800 (PST) Message-ID: Date: Mon, 8 Jan 2024 13:47:21 +0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 08/33] linux-user: Remove qemu_host_page_{size, mask} from mmap.c Content-Language: en-US To: Richard Henderson , qemu-devel@nongnu.org References: <20240102015808.132373-1-richard.henderson@linaro.org> <20240102015808.132373-9-richard.henderson@linaro.org> From: Pierrick Bouvier In-Reply-To: <20240102015808.132373-9-richard.henderson@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2a00:1450:4864:20::32f; envelope-from=pierrick.bouvier@linaro.org; helo=mail-wm1-x32f.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 1/2/24 05:57, Richard Henderson wrote: > Use qemu_real_host_page_size instead. > > Signed-off-by: Richard Henderson > --- > linux-user/mmap.c | 66 +++++++++++++++++++++++------------------------ > 1 file changed, 33 insertions(+), 33 deletions(-) > > diff --git a/linux-user/mmap.c b/linux-user/mmap.c > index 96c9433e27..4d3c8717b9 100644 > --- a/linux-user/mmap.c > +++ b/linux-user/mmap.c > @@ -165,6 +165,7 @@ static int target_to_host_prot(int prot) > /* NOTE: all the constants are the HOST ones, but addresses are target. */ > int target_mprotect(abi_ulong start, abi_ulong len, int target_prot) > { > + int host_page_size = qemu_real_host_page_size(); > abi_ulong starts[3]; > abi_ulong lens[3]; > int prots[3]; > @@ -189,13 +190,13 @@ int target_mprotect(abi_ulong start, abi_ulong len, int target_prot) > } > > last = start + len - 1; > - host_start = start & qemu_host_page_mask; > + host_start = start & -host_page_size; > host_last = HOST_PAGE_ALIGN(last) - 1; > nranges = 0; > > mmap_lock(); > > - if (host_last - host_start < qemu_host_page_size) { > + if (host_last - host_start < host_page_size) { > /* Single host page contains all guest pages: sum the prot. */ > prot1 = target_prot; > for (abi_ulong a = host_start; a < start; a += TARGET_PAGE_SIZE) { > @@ -205,7 +206,7 @@ int target_mprotect(abi_ulong start, abi_ulong len, int target_prot) > prot1 |= page_get_flags(a + 1); > } > starts[nranges] = host_start; > - lens[nranges] = qemu_host_page_size; > + lens[nranges] = host_page_size; > prots[nranges] = prot1; > nranges++; > } else { > @@ -218,10 +219,10 @@ int target_mprotect(abi_ulong start, abi_ulong len, int target_prot) > /* If the resulting sum differs, create a new range. */ > if (prot1 != target_prot) { > starts[nranges] = host_start; > - lens[nranges] = qemu_host_page_size; > + lens[nranges] = host_page_size; > prots[nranges] = prot1; > nranges++; > - host_start += qemu_host_page_size; > + host_start += host_page_size; > } > } > > @@ -233,9 +234,9 @@ int target_mprotect(abi_ulong start, abi_ulong len, int target_prot) > } > /* If the resulting sum differs, create a new range. */ > if (prot1 != target_prot) { > - host_last -= qemu_host_page_size; > + host_last -= host_page_size; > starts[nranges] = host_last + 1; > - lens[nranges] = qemu_host_page_size; > + lens[nranges] = host_page_size; > prots[nranges] = prot1; > nranges++; > } > @@ -270,6 +271,7 @@ int target_mprotect(abi_ulong start, abi_ulong len, int target_prot) > static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong last, > int prot, int flags, int fd, off_t offset) > { > + int host_page_size = qemu_real_host_page_size(); > abi_ulong real_last; > void *host_start; > int prot_old, prot_new; > @@ -286,7 +288,7 @@ static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong last, > return false; > } > > - real_last = real_start + qemu_host_page_size - 1; > + real_last = real_start + host_page_size - 1; > host_start = g2h_untagged(real_start); > > /* Get the protection of the target pages outside the mapping. */ > @@ -304,12 +306,12 @@ static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong last, > * outside of the fragment we need to map. Allocate a new host > * page to cover, discarding whatever else may have been present. > */ > - void *p = mmap(host_start, qemu_host_page_size, > + void *p = mmap(host_start, host_page_size, > target_to_host_prot(prot), > flags | MAP_ANONYMOUS, -1, 0); > if (p != host_start) { > if (p != MAP_FAILED) { > - munmap(p, qemu_host_page_size); > + munmap(p, host_page_size); > errno = EEXIST; > } > return false; > @@ -324,7 +326,7 @@ static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong last, > /* Adjust protection to be able to write. */ > if (!(host_prot_old & PROT_WRITE)) { > host_prot_old |= PROT_WRITE; > - mprotect(host_start, qemu_host_page_size, host_prot_old); > + mprotect(host_start, host_page_size, host_prot_old); > } > > /* Read or zero the new guest pages. */ > @@ -338,7 +340,7 @@ static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong last, > > /* Put final protection */ > if (host_prot_new != host_prot_old) { > - mprotect(host_start, qemu_host_page_size, host_prot_new); > + mprotect(host_start, host_page_size, host_prot_new); > } > return true; > } > @@ -373,17 +375,18 @@ static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size, > */ > abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size, abi_ulong align) > { > + int host_page_size = qemu_real_host_page_size(); > void *ptr, *prev; > abi_ulong addr; > int wrapped, repeat; > > - align = MAX(align, qemu_host_page_size); > + align = MAX(align, host_page_size); > > /* If 'start' == 0, then a default start address is used. */ > if (start == 0) { > start = mmap_next_start; > } else { > - start &= qemu_host_page_mask; > + start &= -host_page_size; > } > start = ROUND_UP(start, align); > > @@ -492,6 +495,7 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size, abi_ulong align) > abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot, > int flags, int fd, off_t offset) > { > + int host_page_size = qemu_real_host_page_size(); > abi_ulong ret, last, real_start, real_last, retaddr, host_len; > abi_ulong passthrough_start = -1, passthrough_last = 0; > int page_flags; > @@ -537,8 +541,8 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot, > } > } > > - real_start = start & qemu_host_page_mask; > - host_offset = offset & qemu_host_page_mask; > + real_start = start & -host_page_size; > + host_offset = offset & -host_page_size; > > /* > * If the user is asking for the kernel to find a location, do that > @@ -567,8 +571,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot, > * may need to truncate file maps at EOF and add extra anonymous pages > * up to the targets page boundary. > */ > - if ((qemu_real_host_page_size() < qemu_host_page_size) && > - !(flags & MAP_ANONYMOUS)) { > + if (host_page_size < TARGET_PAGE_SIZE && !(flags & MAP_ANONYMOUS)) { > struct stat sb; > > if (fstat(fd, &sb) == -1) { > @@ -595,11 +598,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot, > host_len = HOST_PAGE_ALIGN(host_len); > host_prot = target_to_host_prot(target_prot); > > - /* > - * Note: we prefer to control the mapping address. It is > - * especially important if qemu_host_page_size > > - * qemu_real_host_page_size. > - */ > + /* Note: we prefer to control the mapping address. */ > p = mmap(g2h_untagged(start), host_len, host_prot, > flags | MAP_FIXED | MAP_ANONYMOUS, -1, 0); > if (p == MAP_FAILED) { > @@ -665,7 +664,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot, > * aligned, so we read it > */ > if (!(flags & MAP_ANONYMOUS) && > - (offset & ~qemu_host_page_mask) != (start & ~qemu_host_page_mask)) { > + (offset & (host_page_size - 1)) != (start & (host_page_size - 1))) { > /* > * msync() won't work here, so we return an error if write is > * possible while it is a shared mapping > @@ -694,7 +693,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot, > > /* handle the start of the mapping */ > if (start > real_start) { > - if (real_last == real_start + qemu_host_page_size - 1) { > + if (real_last == real_start + host_page_size - 1) { > /* one single host page */ > if (!mmap_frag(real_start, start, last, > target_prot, flags, fd, offset)) { > @@ -703,21 +702,21 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot, > goto the_end1; > } > if (!mmap_frag(real_start, start, > - real_start + qemu_host_page_size - 1, > + real_start + host_page_size - 1, > target_prot, flags, fd, offset)) { > goto fail; > } > - real_start += qemu_host_page_size; > + real_start += host_page_size; > } > /* handle the end of the mapping */ > if (last < real_last) { > - abi_ulong real_page = real_last - qemu_host_page_size + 1; > + abi_ulong real_page = real_last - host_page_size + 1; > if (!mmap_frag(real_page, real_page, last, > target_prot, flags, fd, > offset + real_page - start)) { > goto fail; > } > - real_last -= qemu_host_page_size; > + real_last -= host_page_size; > } > > /* map the middle (easier) */ > @@ -784,6 +783,7 @@ fail: > > static int mmap_reserve_or_unmap(abi_ulong start, abi_ulong len) > { > + int host_page_size = qemu_real_host_page_size(); > abi_ulong real_start; > abi_ulong real_last; > abi_ulong real_len; > @@ -793,7 +793,7 @@ static int mmap_reserve_or_unmap(abi_ulong start, abi_ulong len) > int prot; > > last = start + len - 1; > - real_start = start & qemu_host_page_mask; > + real_start = start & -host_page_size; > real_last = HOST_PAGE_ALIGN(last) - 1; > > /* > @@ -802,7 +802,7 @@ static int mmap_reserve_or_unmap(abi_ulong start, abi_ulong len) > * The single page special case is required for the last page, > * lest real_start overflow to zero. > */ > - if (real_last - real_start < qemu_host_page_size) { > + if (real_last - real_start < host_page_size) { > prot = 0; > for (a = real_start; a < start; a += TARGET_PAGE_SIZE) { > prot |= page_get_flags(a); > @@ -818,14 +818,14 @@ static int mmap_reserve_or_unmap(abi_ulong start, abi_ulong len) > prot |= page_get_flags(a); > } > if (prot != 0) { > - real_start += qemu_host_page_size; > + real_start += host_page_size; > } > > for (prot = 0, a = last; a < real_last; a += TARGET_PAGE_SIZE) { > prot |= page_get_flags(a + 1); > } > if (prot != 0) { > - real_last -= qemu_host_page_size; > + real_last -= host_page_size; > } > > if (real_last < real_start) { For me, the transformation ~page_mask == page_size - 1 and page_mask == -page_size was not so intuitive, until I tried it on paper. Could it be useful to have macros PAGE_BITS(page_size), and PAGE_MASK(page_size) for this?. All would be defined from page_sz, so there is no duplicated data, and it would avoid a subtle error when forgetting an operator, while helping to read the code. Reviewed-by: Pierrick Bouvier