| Message ID | 20190519201953.20161-13-richard.henderson@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | linux-user: path, clone, sparc, shmat fixes | expand |
On 19/05/2019 22:19, Richard Henderson wrote: > For those hosts with SHMLBA > getpagesize, we don't automatically > select a guest address that is compatible with the host. We can > achieve this by boosting the alignment of guest_base and by adding > an extra alignment argument to mmap_find_vma. > > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > --- > linux-user/qemu.h | 2 +- > linux-user/elfload.c | 17 +++++----- > linux-user/mmap.c | 74 +++++++++++++++++++++++--------------------- > linux-user/syscall.c | 3 +- > 4 files changed, 52 insertions(+), 44 deletions(-) > > diff --git a/linux-user/qemu.h b/linux-user/qemu.h > index ef400cb78a..82d33d7e93 100644 > --- a/linux-user/qemu.h > +++ b/linux-user/qemu.h > @@ -443,7 +443,7 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size, > abi_ulong new_addr); > extern unsigned long last_brk; > extern abi_ulong mmap_next_start; > -abi_ulong mmap_find_vma(abi_ulong, abi_ulong); > +abi_ulong mmap_find_vma(abi_ulong, abi_ulong, abi_ulong); > void mmap_fork_start(void); > void mmap_fork_end(int child); > > diff --git a/linux-user/elfload.c b/linux-user/elfload.c > index ef42e02d82..fe9f07843e 100644 > --- a/linux-user/elfload.c > +++ b/linux-user/elfload.c > @@ -3,6 +3,7 @@ > #include <sys/param.h> > > #include <sys/resource.h> > +#include <sys/shm.h> > > #include "qemu.h" > #include "disas/disas.h" > @@ -2012,6 +2013,8 @@ unsigned long init_guest_space(unsigned long host_start, > unsigned long guest_start, > bool fixed) > { > + /* In order to use host shmat, we must be able to honor SHMLBA. */ > + unsigned long align = MAX(SHMLBA, qemu_host_page_size); > unsigned long current_start, aligned_start; > int flags; > > @@ -2029,7 +2032,7 @@ unsigned long init_guest_space(unsigned long host_start, > } > > /* Setup the initial flags and start address. */ > - current_start = host_start & qemu_host_page_mask; > + current_start = host_start & -align; > flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE; > if (fixed) { > flags |= MAP_FIXED; > @@ -2065,8 +2068,8 @@ unsigned long init_guest_space(unsigned long host_start, > return (unsigned long)-1; > } > munmap((void *)real_start, host_full_size); > - if (real_start & ~qemu_host_page_mask) { > - /* The same thing again, but with an extra qemu_host_page_size > + if (real_start & (align - 1)) { > + /* The same thing again, but with extra > * so that we can shift around alignment. > */ > unsigned long real_size = host_full_size + qemu_host_page_size; > @@ -2079,7 +2082,7 @@ unsigned long init_guest_space(unsigned long host_start, > return (unsigned long)-1; > } > munmap((void *)real_start, real_size); > - real_start = HOST_PAGE_ALIGN(real_start); > + real_start = ROUND_UP(real_start, align); > } > current_start = real_start; > } > @@ -2106,7 +2109,7 @@ unsigned long init_guest_space(unsigned long host_start, > } > > /* Ensure the address is properly aligned. */ > - if (real_start & ~qemu_host_page_mask) { > + if (real_start & (align - 1)) { > /* Ideally, we adjust like > * > * pages: [ ][ ][ ][ ][ ] > @@ -2134,7 +2137,7 @@ unsigned long init_guest_space(unsigned long host_start, > if (real_start == (unsigned long)-1) { > return (unsigned long)-1; > } > - aligned_start = HOST_PAGE_ALIGN(real_start); > + aligned_start = ROUND_UP(real_start, align); > } else { > aligned_start = real_start; > } > @@ -2171,7 +2174,7 @@ unsigned long init_guest_space(unsigned long host_start, > * because of trouble with ARM commpage setup. > */ > munmap((void *)real_start, real_size); > - current_start += qemu_host_page_size; > + current_start += align; > if (host_start == current_start) { > /* Theoretically possible if host doesn't have any suitably > * aligned areas. Normally the first mmap will fail. > diff --git a/linux-user/mmap.c b/linux-user/mmap.c > index e0249efe4f..10796b37ac 100644 > --- a/linux-user/mmap.c > +++ b/linux-user/mmap.c > @@ -202,49 +202,52 @@ unsigned long last_brk; > > /* Subroutine of mmap_find_vma, used when we have pre-allocated a chunk > of guest address space. */ > -static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size) > +static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size, > + abi_ulong align) > { > - abi_ulong addr; > - abi_ulong end_addr; > + abi_ulong addr, end_addr, incr = qemu_host_page_size; > int prot; > - int looped = 0; > + bool looped = false; > > if (size > reserved_va) { > return (abi_ulong)-1; > } > > - size = HOST_PAGE_ALIGN(size); > - end_addr = start + size; > - if (end_addr > reserved_va) { > - end_addr = reserved_va; > - } > - addr = end_addr - qemu_host_page_size; > + /* Note that start and size have already been aligned by mmap_find_vma. */ > > + end_addr = start + size; > + if (start > reserved_va - size) { > + /* Start at the top of the address space. */ > + end_addr = ((reserved_va - size) & -align) + size; > + looped = true; > + } > + > + /* Search downward from END_ADDR, checking to see if a page is in use. */ > + addr = end_addr; > while (1) { > + addr -= incr; > if (addr > end_addr) { > if (looped) { > + /* Failure. The entire address space has been searched. */ > return (abi_ulong)-1; > } > - end_addr = reserved_va; > - addr = end_addr - qemu_host_page_size; > - looped = 1; > - continue; > + /* Re-start at the top of the address space. */ > + addr = end_addr = ((reserved_va - size) & -align) + size; > + looped = true; > + } else { > + prot = page_get_flags(addr); > + if (prot) { > + /* Page in use. Restart below this page. */ > + addr = end_addr = ((addr - size) & -align) + size; > + } else if (addr && addr + size == end_addr) { > + /* Success! All pages between ADDR and END_ADDR are free. */ > + if (start == mmap_next_start) { > + mmap_next_start = addr; > + } > + return addr; > + } > } > - prot = page_get_flags(addr); > - if (prot) { > - end_addr = addr; > - } > - if (addr && addr + size == end_addr) { > - break; > - } > - addr -= qemu_host_page_size; > } > - > - if (start == mmap_next_start) { > - mmap_next_start = addr; > - } > - > - return addr; > } > > /* > @@ -253,7 +256,7 @@ static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size) > * It must be called with mmap_lock() held. > * Return -1 if error. > */ > -abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) > +abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size, abi_ulong align) > { > void *ptr, *prev; > abi_ulong addr; > @@ -265,11 +268,12 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) > } else { > start &= qemu_host_page_mask; > } > + start = ROUND_UP(start, align); > > size = HOST_PAGE_ALIGN(size); > > if (reserved_va) { > - return mmap_find_vma_reserved(start, size); > + return mmap_find_vma_reserved(start, size, align); > } > > addr = start; > @@ -299,7 +303,7 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) > if (h2g_valid(ptr + size - 1)) { > addr = h2g(ptr); > > - if ((addr & ~TARGET_PAGE_MASK) == 0) { > + if ((addr & (align - 1)) == 0) { > /* Success. */ > if (start == mmap_next_start && addr >= TASK_UNMAPPED_BASE) { > mmap_next_start = addr + size; > @@ -313,12 +317,12 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) > /* Assume the result that the kernel gave us is the > first with enough free space, so start again at the > next higher target page. */ > - addr = TARGET_PAGE_ALIGN(addr); > + addr = ROUND_UP(addr, align); > break; > case 1: > /* Sometimes the kernel decides to perform the allocation > at the top end of memory instead. */ > - addr &= TARGET_PAGE_MASK; > + addr &= -align; > break; > case 2: > /* Start over at low memory. */ > @@ -416,7 +420,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, > if (!(flags & MAP_FIXED)) { > host_len = len + offset - host_offset; > host_len = HOST_PAGE_ALIGN(host_len); > - start = mmap_find_vma(real_start, host_len); > + start = mmap_find_vma(real_start, host_len, TARGET_PAGE_SIZE); > if (start == (abi_ulong)-1) { > errno = ENOMEM; > goto fail; > @@ -710,7 +714,7 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size, > } else if (flags & MREMAP_MAYMOVE) { > abi_ulong mmap_start; > > - mmap_start = mmap_find_vma(0, new_size); > + mmap_start = mmap_find_vma(0, new_size, TARGET_PAGE_SIZE); > > if (mmap_start == -1) { > errno = ENOMEM; > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index f960556bf8..1feb740f66 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -3912,7 +3912,8 @@ static inline abi_ulong do_shmat(CPUArchState *cpu_env, > else { > abi_ulong mmap_start; > > - mmap_start = mmap_find_vma(0, shm_info.shm_segsz); > + /* In order to use the host shmat, we need to honor host SHMLBA. */ > + mmap_start = mmap_find_vma(0, shm_info.shm_segsz, MAX(SHMLBA, shmlba)); > > if (mmap_start == -1) { > errno = ENOMEM; > Applied to my linux-user branch. Thanks, Laurent
diff --git a/linux-user/qemu.h b/linux-user/qemu.h index ef400cb78a..82d33d7e93 100644 --- a/linux-user/qemu.h +++ b/linux-user/qemu.h @@ -443,7 +443,7 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size, abi_ulong new_addr); extern unsigned long last_brk; extern abi_ulong mmap_next_start; -abi_ulong mmap_find_vma(abi_ulong, abi_ulong); +abi_ulong mmap_find_vma(abi_ulong, abi_ulong, abi_ulong); void mmap_fork_start(void); void mmap_fork_end(int child); diff --git a/linux-user/elfload.c b/linux-user/elfload.c index ef42e02d82..fe9f07843e 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -3,6 +3,7 @@ #include <sys/param.h> #include <sys/resource.h> +#include <sys/shm.h> #include "qemu.h" #include "disas/disas.h" @@ -2012,6 +2013,8 @@ unsigned long init_guest_space(unsigned long host_start, unsigned long guest_start, bool fixed) { + /* In order to use host shmat, we must be able to honor SHMLBA. */ + unsigned long align = MAX(SHMLBA, qemu_host_page_size); unsigned long current_start, aligned_start; int flags; @@ -2029,7 +2032,7 @@ unsigned long init_guest_space(unsigned long host_start, } /* Setup the initial flags and start address. */ - current_start = host_start & qemu_host_page_mask; + current_start = host_start & -align; flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE; if (fixed) { flags |= MAP_FIXED; @@ -2065,8 +2068,8 @@ unsigned long init_guest_space(unsigned long host_start, return (unsigned long)-1; } munmap((void *)real_start, host_full_size); - if (real_start & ~qemu_host_page_mask) { - /* The same thing again, but with an extra qemu_host_page_size + if (real_start & (align - 1)) { + /* The same thing again, but with extra * so that we can shift around alignment. */ unsigned long real_size = host_full_size + qemu_host_page_size; @@ -2079,7 +2082,7 @@ unsigned long init_guest_space(unsigned long host_start, return (unsigned long)-1; } munmap((void *)real_start, real_size); - real_start = HOST_PAGE_ALIGN(real_start); + real_start = ROUND_UP(real_start, align); } current_start = real_start; } @@ -2106,7 +2109,7 @@ unsigned long init_guest_space(unsigned long host_start, } /* Ensure the address is properly aligned. */ - if (real_start & ~qemu_host_page_mask) { + if (real_start & (align - 1)) { /* Ideally, we adjust like * * pages: [ ][ ][ ][ ][ ] @@ -2134,7 +2137,7 @@ unsigned long init_guest_space(unsigned long host_start, if (real_start == (unsigned long)-1) { return (unsigned long)-1; } - aligned_start = HOST_PAGE_ALIGN(real_start); + aligned_start = ROUND_UP(real_start, align); } else { aligned_start = real_start; } @@ -2171,7 +2174,7 @@ unsigned long init_guest_space(unsigned long host_start, * because of trouble with ARM commpage setup. */ munmap((void *)real_start, real_size); - current_start += qemu_host_page_size; + current_start += align; if (host_start == current_start) { /* Theoretically possible if host doesn't have any suitably * aligned areas. Normally the first mmap will fail. diff --git a/linux-user/mmap.c b/linux-user/mmap.c index e0249efe4f..10796b37ac 100644 --- a/linux-user/mmap.c +++ b/linux-user/mmap.c @@ -202,49 +202,52 @@ unsigned long last_brk; /* Subroutine of mmap_find_vma, used when we have pre-allocated a chunk of guest address space. */ -static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size) +static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size, + abi_ulong align) { - abi_ulong addr; - abi_ulong end_addr; + abi_ulong addr, end_addr, incr = qemu_host_page_size; int prot; - int looped = 0; + bool looped = false; if (size > reserved_va) { return (abi_ulong)-1; } - size = HOST_PAGE_ALIGN(size); - end_addr = start + size; - if (end_addr > reserved_va) { - end_addr = reserved_va; - } - addr = end_addr - qemu_host_page_size; + /* Note that start and size have already been aligned by mmap_find_vma. */ + end_addr = start + size; + if (start > reserved_va - size) { + /* Start at the top of the address space. */ + end_addr = ((reserved_va - size) & -align) + size; + looped = true; + } + + /* Search downward from END_ADDR, checking to see if a page is in use. */ + addr = end_addr; while (1) { + addr -= incr; if (addr > end_addr) { if (looped) { + /* Failure. The entire address space has been searched. */ return (abi_ulong)-1; } - end_addr = reserved_va; - addr = end_addr - qemu_host_page_size; - looped = 1; - continue; + /* Re-start at the top of the address space. */ + addr = end_addr = ((reserved_va - size) & -align) + size; + looped = true; + } else { + prot = page_get_flags(addr); + if (prot) { + /* Page in use. Restart below this page. */ + addr = end_addr = ((addr - size) & -align) + size; + } else if (addr && addr + size == end_addr) { + /* Success! All pages between ADDR and END_ADDR are free. */ + if (start == mmap_next_start) { + mmap_next_start = addr; + } + return addr; + } } - prot = page_get_flags(addr); - if (prot) { - end_addr = addr; - } - if (addr && addr + size == end_addr) { - break; - } - addr -= qemu_host_page_size; } - - if (start == mmap_next_start) { - mmap_next_start = addr; - } - - return addr; } /* @@ -253,7 +256,7 @@ static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size) * It must be called with mmap_lock() held. * Return -1 if error. */ -abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) +abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size, abi_ulong align) { void *ptr, *prev; abi_ulong addr; @@ -265,11 +268,12 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) } else { start &= qemu_host_page_mask; } + start = ROUND_UP(start, align); size = HOST_PAGE_ALIGN(size); if (reserved_va) { - return mmap_find_vma_reserved(start, size); + return mmap_find_vma_reserved(start, size, align); } addr = start; @@ -299,7 +303,7 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) if (h2g_valid(ptr + size - 1)) { addr = h2g(ptr); - if ((addr & ~TARGET_PAGE_MASK) == 0) { + if ((addr & (align - 1)) == 0) { /* Success. */ if (start == mmap_next_start && addr >= TASK_UNMAPPED_BASE) { mmap_next_start = addr + size; @@ -313,12 +317,12 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) /* Assume the result that the kernel gave us is the first with enough free space, so start again at the next higher target page. */ - addr = TARGET_PAGE_ALIGN(addr); + addr = ROUND_UP(addr, align); break; case 1: /* Sometimes the kernel decides to perform the allocation at the top end of memory instead. */ - addr &= TARGET_PAGE_MASK; + addr &= -align; break; case 2: /* Start over at low memory. */ @@ -416,7 +420,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, if (!(flags & MAP_FIXED)) { host_len = len + offset - host_offset; host_len = HOST_PAGE_ALIGN(host_len); - start = mmap_find_vma(real_start, host_len); + start = mmap_find_vma(real_start, host_len, TARGET_PAGE_SIZE); if (start == (abi_ulong)-1) { errno = ENOMEM; goto fail; @@ -710,7 +714,7 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size, } else if (flags & MREMAP_MAYMOVE) { abi_ulong mmap_start; - mmap_start = mmap_find_vma(0, new_size); + mmap_start = mmap_find_vma(0, new_size, TARGET_PAGE_SIZE); if (mmap_start == -1) { errno = ENOMEM; diff --git a/linux-user/syscall.c b/linux-user/syscall.c index f960556bf8..1feb740f66 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -3912,7 +3912,8 @@ static inline abi_ulong do_shmat(CPUArchState *cpu_env, else { abi_ulong mmap_start; - mmap_start = mmap_find_vma(0, shm_info.shm_segsz); + /* In order to use the host shmat, we need to honor host SHMLBA. */ + mmap_start = mmap_find_vma(0, shm_info.shm_segsz, MAX(SHMLBA, shmlba)); if (mmap_start == -1) { errno = ENOMEM;
For those hosts with SHMLBA > getpagesize, we don't automatically select a guest address that is compatible with the host. We can achieve this by boosting the alignment of guest_base and by adding an extra alignment argument to mmap_find_vma. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- linux-user/qemu.h | 2 +- linux-user/elfload.c | 17 +++++----- linux-user/mmap.c | 74 +++++++++++++++++++++++--------------------- linux-user/syscall.c | 3 +- 4 files changed, 52 insertions(+), 44 deletions(-) -- 2.17.1