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elf2dmp: use Linux mmap with MAP_NORESERVE when possible

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Glib's g_mapped_file_new maps file with PROT_READ|PROT_WRITE and
MAP_PRIVATE. This leads to premature physical memory allocation of dump
file size on Linux hosts and may fail. On Linux, mapping the file with
MAP_NORESERVE limits the allocation by available memory.

Signed-off-by: Viktor Prutyanov <viktor@daynix.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-id: 20230915170153.10959-5-viktor@daynix.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Viktor Prutyanov 2023-09-15 20:01:52 +03:00 committed by Peter Maydell
parent 9b7dcd8ff4
commit df7a75564e
2 changed files with 58 additions and 12 deletions
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68
contrib/elf2dmp/qemu_elf.c
View File

@ -165,10 +165,40 @@ static bool check_ehdr(QEMU_Elf *qe)
return true;
}
int QEMU_Elf_init(QEMU_Elf *qe, const char *filename)
static int QEMU_Elf_map(QEMU_Elf *qe, const char *filename)
{
#ifdef CONFIG_LINUX
struct stat st;
int fd;
printf("Using Linux mmap\n");
fd = open(filename, O_RDONLY, 0);
if (fd == -1) {
eprintf("Failed to open ELF dump file \'%s\'\n", filename);
return 1;
}
if (fstat(fd, &st)) {
eprintf("Failed to get size of ELF dump file\n");
close(fd);
return 1;
}
qe->size = st.st_size;
qe->map = mmap(NULL, qe->size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_NORESERVE, fd, 0);
if (qe->map == MAP_FAILED) {
eprintf("Failed to map ELF file\n");
close(fd);
return 1;
}
close(fd);
#else
GError *gerr = NULL;
int err = 0;
printf("Using GLib mmap\n");
qe->gmf = g_mapped_file_new(filename, TRUE, &gerr);
if (gerr) {
@ -179,29 +209,43 @@ int QEMU_Elf_init(QEMU_Elf *qe, const char *filename)
qe->map = g_mapped_file_get_contents(qe->gmf);
qe->size = g_mapped_file_get_length(qe->gmf);
#endif
return 0;
}
static void QEMU_Elf_unmap(QEMU_Elf *qe)
{
#ifdef CONFIG_LINUX
munmap(qe->map, qe->size);
#else
g_mapped_file_unref(qe->gmf);
#endif
}
int QEMU_Elf_init(QEMU_Elf *qe, const char *filename)
{
if (QEMU_Elf_map(qe, filename)) {
return 1;
}
if (!check_ehdr(qe)) {
eprintf("Input file has the wrong format\n");
err = 1;
goto out_unmap;
QEMU_Elf_unmap(qe);
return 1;
}
if (init_states(qe)) {
eprintf("Failed to extract QEMU CPU states\n");
err = 1;
goto out_unmap;
QEMU_Elf_unmap(qe);
return 1;
}
return 0;
out_unmap:
g_mapped_file_unref(qe->gmf);
return err;
}
void QEMU_Elf_exit(QEMU_Elf *qe)
{
exit_states(qe);
g_mapped_file_unref(qe->gmf);
QEMU_Elf_unmap(qe);
}

2
contrib/elf2dmp/qemu_elf.h
View File

@ -32,7 +32,9 @@ typedef struct QEMUCPUState {
int is_system(QEMUCPUState *s);
typedef struct QEMU_Elf {
#ifndef CONFIG_LINUX
GMappedFile *gmf;
#endif
size_t size;
void *map;
QEMUCPUState **state;