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linux-user/elfload: Rely on walk_memory_regions for vmas
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Rather than creating new data structures for vma,
rely on the IntervalTree used by walk_memory_regions.

Use PAGE_* constants, per the page table api, rather
than PROT_* constants, per the mmap api.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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@rth7680
rth7680 committed Feb 29, 2024
1 parent 1928d50 commit 50e33f5
Showing 1 changed file with 78 additions and 135 deletions.
213 changes: 78 additions & 135 deletions linux-user/elfload.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4041,29 +4041,6 @@ struct target_elf_prpsinfo {
char pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */
};

struct vm_area_struct {
target_ulong vma_start; /* start vaddr of memory region */
target_ulong vma_end; /* end vaddr of memory region */
abi_ulong vma_flags; /* protection etc. flags for the region */
QTAILQ_ENTRY(vm_area_struct) vma_link;
};

struct mm_struct {
QTAILQ_HEAD(, vm_area_struct) mm_mmap;
int mm_count; /* number of mappings */
};

static void vma_init(struct mm_struct *);
static void vma_delete(struct mm_struct *);
static int vma_add_mapping(struct mm_struct *, target_ulong,
target_ulong, abi_ulong);
static int vma_get_mapping_count(const struct mm_struct *);
static struct vm_area_struct *vma_first(const struct mm_struct *);
static struct vm_area_struct *vma_next(struct vm_area_struct *);
static abi_ulong vma_dump_size(const struct vm_area_struct *);
static int vma_walker(void *priv, target_ulong start, target_ulong end,
unsigned long flags);

#ifdef BSWAP_NEEDED
static void bswap_prstatus(struct target_elf_prstatus *prstatus)
{
Expand Down Expand Up @@ -4105,69 +4082,14 @@ static inline void bswap_psinfo(struct target_elf_prpsinfo *p) {}
static inline void bswap_note(struct elf_note *en) { }
#endif /* BSWAP_NEEDED */

/*
* Minimal support for linux memory regions. These are needed
* when we are finding out what memory exactly belongs to
* emulated process. No locks needed here, as long as
* thread that received the signal is stopped.
*/

static void vma_init(struct mm_struct *mm)
{
mm->mm_count = 0;
QTAILQ_INIT(&mm->mm_mmap);
}

static void vma_delete(struct mm_struct *mm)
{
struct vm_area_struct *vma;

while ((vma = vma_first(mm)) != NULL) {
QTAILQ_REMOVE(&mm->mm_mmap, vma, vma_link);
g_free(vma);
}
}

static int vma_add_mapping(struct mm_struct *mm, target_ulong start,
target_ulong end, abi_ulong flags)
{
struct vm_area_struct *vma;

if ((vma = g_malloc0(sizeof (*vma))) == NULL)
return (-1);

vma->vma_start = start;
vma->vma_end = end;
vma->vma_flags = flags;

QTAILQ_INSERT_TAIL(&mm->mm_mmap, vma, vma_link);
mm->mm_count++;

return (0);
}

static struct vm_area_struct *vma_first(const struct mm_struct *mm)
{
return (QTAILQ_FIRST(&mm->mm_mmap));
}

static struct vm_area_struct *vma_next(struct vm_area_struct *vma)
{
return (QTAILQ_NEXT(vma, vma_link));
}

static int vma_get_mapping_count(const struct mm_struct *mm)
{
return (mm->mm_count);
}

/*
* Calculate file (dump) size of given memory region.
*/
static abi_ulong vma_dump_size(const struct vm_area_struct *vma)
static size_t vma_dump_size(target_ulong start, target_ulong end,
unsigned long flags)
{
/* The area must be readable. */
if (!(vma->vma_flags & PROT_READ)) {
if (!(flags & PAGE_READ)) {
return 0;
}

Expand All @@ -4176,22 +4098,13 @@ static abi_ulong vma_dump_size(const struct vm_area_struct *vma)
* non-writable code that debugger can read directly from
* target library etc. If there is no elf header, we dump it.
*/
if (!(vma->vma_flags & PROT_WRITE) &&
(vma->vma_flags & PROT_EXEC) &&
memcmp(g2h_untagged(vma->vma_start), ELFMAG, SELFMAG) == 0) {
if (!(flags & PAGE_WRITE_ORG) &&
(flags & PAGE_EXEC) &&
memcmp(g2h_untagged(start), ELFMAG, SELFMAG) == 0) {
return 0;
}

return vma->vma_end - vma->vma_start;
}

static int vma_walker(void *priv, target_ulong start, target_ulong end,
unsigned long flags)
{
struct mm_struct *mm = (struct mm_struct *)priv;

vma_add_mapping(mm, start, end, flags);
return (0);
return end - start;
}

static size_t size_note(const char *name, size_t datasz)
Expand Down Expand Up @@ -4367,6 +4280,61 @@ static int dump_write(int fd, const void *ptr, size_t size)
return (0);
}

typedef struct {
unsigned count;
size_t size;
} CountAndSizeRegions;

static int wmr_count_and_size_regions(void *opaque, target_ulong start,
target_ulong end, unsigned long flags)
{
CountAndSizeRegions *css = opaque;

css->count++;
css->size += vma_dump_size(start, end, flags);
return 0;
}

typedef struct {
struct elf_phdr *phdr;
off_t offset;
} FillRegionPhdr;

static int wmr_fill_region_phdr(void *opaque, target_ulong start,
target_ulong end, unsigned long flags)
{
FillRegionPhdr *d = opaque;
struct elf_phdr *phdr = d->phdr;

phdr->p_type = PT_LOAD;
phdr->p_vaddr = start;
phdr->p_paddr = 0;
phdr->p_filesz = vma_dump_size(start, end, flags);
phdr->p_offset = d->offset;
d->offset += phdr->p_filesz;
phdr->p_memsz = end - start;
phdr->p_flags = (flags & PAGE_READ ? PF_R : 0)
| (flags & PAGE_WRITE_ORG ? PF_W : 0)
| (flags & PAGE_EXEC ? PF_X : 0);
phdr->p_align = ELF_EXEC_PAGESIZE;

bswap_phdr(phdr, 1);
d->phdr = phdr + 1;
return 0;
}

static int wmr_write_region(void *opaque, target_ulong start,
target_ulong end, unsigned long flags)
{
int fd = *(int *)opaque;
size_t size = vma_dump_size(start, end, flags);

if (!size) {
return 0;
}
return dump_write(fd, g2h_untagged(start), size);
}

/*
* Write out ELF coredump.
*
Expand Down Expand Up @@ -4414,12 +4382,11 @@ static int elf_core_dump(int signr, const CPUArchState *env)
{
const CPUState *cpu = env_cpu((CPUArchState *)env);
const TaskState *ts = (const TaskState *)cpu->opaque;
struct vm_area_struct *vma;
struct rlimit dumpsize;
struct mm_struct mm;
CountAndSizeRegions css;
off_t offset, note_offset, data_offset;
size_t note_size;
int segs, cpus, ret;
int cpus, ret;
int fd = -1;
CPUState *cpu_iter;

Expand All @@ -4438,32 +4405,27 @@ static int elf_core_dump(int signr, const CPUArchState *env)
* Walk through target process memory mappings and
* set up structure containing this information.
*/
vma_init(&mm);
walk_memory_regions(&mm, vma_walker);
segs = vma_get_mapping_count(&mm);
memset(&css, 0, sizeof(css));
walk_memory_regions(&css, wmr_count_and_size_regions);

cpus = 0;
CPU_FOREACH(cpu_iter) {
cpus++;
}

offset = sizeof(struct elfhdr);
offset += (segs + 1) * sizeof(struct elf_phdr);
offset += (css.count + 1) * sizeof(struct elf_phdr);
note_offset = offset;

offset += size_note("CORE", ts->info->auxv_len);
offset += size_note("CORE", sizeof(struct target_elf_prpsinfo));
offset += size_note("CORE", sizeof(struct target_elf_prstatus)) * cpus;
note_size = offset - note_offset;
offset = ROUND_UP(offset, ELF_EXEC_PAGESIZE);
data_offset = offset;

for (vma = vma_first(&mm); vma != NULL; vma = vma_next(vma)) {
offset += vma_dump_size(vma);
}
data_offset = ROUND_UP(offset, ELF_EXEC_PAGESIZE);

/* Do not dump if the corefile size exceeds the limit. */
if (dumpsize.rlim_cur != RLIM_INFINITY && dumpsize.rlim_cur < offset) {
if (dumpsize.rlim_cur != RLIM_INFINITY
&& dumpsize.rlim_cur < data_offset + css.size) {
errno = 0;
goto out;
}
Expand All @@ -4485,36 +4447,22 @@ static int elf_core_dump(int signr, const CPUArchState *env)
*/
{
g_autofree void *header = g_malloc0(data_offset);
FillRegionPhdr frp;
void *hptr, *dptr;

/* Create elf file header. */
hptr = header;
fill_elf_header(hptr, segs + 1, ELF_MACHINE, 0);
fill_elf_header(hptr, css.count + 1, ELF_MACHINE, 0);
hptr += sizeof(struct elfhdr);

/* Create elf program headers. */
fill_elf_note_phdr(hptr, note_size, note_offset);
hptr += sizeof(struct elf_phdr);

offset = data_offset;
for (vma = vma_first(&mm); vma != NULL; vma = vma_next(vma)) {
struct elf_phdr *phdr = hptr;

phdr->p_type = PT_LOAD;
phdr->p_offset = offset;
phdr->p_vaddr = vma->vma_start;
phdr->p_paddr = 0;
phdr->p_filesz = vma_dump_size(vma);
offset += phdr->p_filesz;
phdr->p_memsz = vma->vma_end - vma->vma_start;
phdr->p_flags = (vma->vma_flags & PROT_READ ? PF_R : 0)
| (vma->vma_flags & PROT_WRITE ? PF_W : 0)
| (vma->vma_flags & PROT_EXEC ? PF_X : 0);
phdr->p_align = ELF_EXEC_PAGESIZE;

bswap_phdr(phdr, 1);
hptr += sizeof(struct elf_phdr);
}
frp.phdr = hptr;
frp.offset = data_offset;
walk_memory_regions(&frp, wmr_fill_region_phdr);
hptr = frp.phdr;

/* Create the notes. */
dptr = fill_note(&hptr, NT_AUXV, "CORE", ts->info->auxv_len);
Expand All @@ -4539,20 +4487,15 @@ static int elf_core_dump(int signr, const CPUArchState *env)
/*
* Finally write process memory into the corefile as well.
*/
for (vma = vma_first(&mm); vma != NULL; vma = vma_next(vma)) {
size_t size = vma_dump_size(vma);

if (size && dump_write(fd, g2h_untagged(vma->vma_start), size) < 0) {
goto out;
}
if (walk_memory_regions(&fd, wmr_write_region) < 0) {
goto out;
}
errno = 0;

out:
ret = -errno;
mmap_unlock();
cpu_list_unlock();
vma_delete(&mm);
close(fd);
return ret;
}
Expand Down

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