From: imp@bsdimp.com
To: qemu-devel@nongnu.org
Cc: "Kyle Evans" <kevans@FreeBSD.org>,
"Warner Losh" <imp@FreeBSD.org>, "Warner Losh" <imp@bsdimp.com>,
"Mikaël Urankar" <mikael.urankar@gmail.com>,
"Stacey Son" <sson@FreeBSD.org>
Subject: [PULL 38/42] bsd-user: Refactor load_elf_sections and is_target_elf_binary
Date: Tue, 7 Sep 2021 15:53:28 -0600 [thread overview]
Message-ID: <20210907215332.30737-39-imp@bsdimp.com> (raw)
In-Reply-To: <20210907215332.30737-1-imp@bsdimp.com>
From: Warner Losh <imp@FreeBSD.org>
Factor out load_elf_sections and is_target_elf_binary out of
load_elf_interp.
Signed-off-by: Mikaël Urankar <mikael.urankar@gmail.com>
Signed-off-by: Stacey Son <sson@FreeBSD.org>
Signed-off-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Kyle Evans <kevans@FreeBSD.org>
---
bsd-user/elfload.c | 344 +++++++++++++++++++++------------------------
1 file changed, 158 insertions(+), 186 deletions(-)
diff --git a/bsd-user/elfload.c b/bsd-user/elfload.c
index 3660961582..142a5bfac2 100644
--- a/bsd-user/elfload.c
+++ b/bsd-user/elfload.c
@@ -36,6 +36,8 @@ abi_ulong target_stksiz;
abi_ulong target_stkbas;
static int elf_core_dump(int signr, CPUArchState *env);
+static int load_elf_sections(const struct elfhdr *hdr, struct elf_phdr *phdr,
+ int fd, abi_ulong rbase, abi_ulong *baddrp);
static inline void memcpy_fromfs(void *to, const void *from, unsigned long n)
{
@@ -271,16 +273,10 @@ static abi_ulong load_elf_interp(struct elfhdr *interp_elf_ex,
abi_ulong *interp_load_addr)
{
struct elf_phdr *elf_phdata = NULL;
- struct elf_phdr *eppnt;
- abi_ulong load_addr = 0;
- int load_addr_set = 0;
+ abi_ulong rbase;
int retval;
- abi_ulong last_bss, elf_bss;
- abi_ulong error;
- int i;
+ abi_ulong baddr, error;
- elf_bss = 0;
- last_bss = 0;
error = 0;
bswap_ehdr(interp_elf_ex);
@@ -325,93 +321,33 @@ static abi_ulong load_elf_interp(struct elfhdr *interp_elf_ex,
}
bswap_phdr(elf_phdata, interp_elf_ex->e_phnum);
+ rbase = 0;
if (interp_elf_ex->e_type == ET_DYN) {
/*
* In order to avoid hardcoding the interpreter load
* address in qemu, we allocate a big enough memory zone.
*/
- error = target_mmap(0, INTERP_MAP_SIZE, PROT_NONE,
+ rbase = target_mmap(0, INTERP_MAP_SIZE, PROT_NONE,
MAP_PRIVATE | MAP_ANON, -1, 0);
- if (error == -1) {
+ if (rbase == -1) {
perror("mmap");
exit(-1);
}
- load_addr = error;
- load_addr_set = 1;
- }
-
- eppnt = elf_phdata;
- for (i = 0; i < interp_elf_ex->e_phnum; i++, eppnt++)
- if (eppnt->p_type == PT_LOAD) {
- int elf_type = MAP_PRIVATE | MAP_DENYWRITE;
- int elf_prot = 0;
- abi_ulong vaddr = 0;
- abi_ulong k;
-
- if (eppnt->p_flags & PF_R) elf_prot = PROT_READ;
- if (eppnt->p_flags & PF_W) elf_prot |= PROT_WRITE;
- if (eppnt->p_flags & PF_X) elf_prot |= PROT_EXEC;
- if (interp_elf_ex->e_type == ET_EXEC || load_addr_set) {
- elf_type |= MAP_FIXED;
- vaddr = eppnt->p_vaddr;
- }
- error = target_mmap(load_addr + TARGET_ELF_PAGESTART(vaddr),
- eppnt->p_filesz + TARGET_ELF_PAGEOFFSET(eppnt->p_vaddr),
- elf_prot,
- elf_type,
- interpreter_fd,
- eppnt->p_offset - TARGET_ELF_PAGEOFFSET(eppnt->p_vaddr));
-
- if (error == -1) {
- /* Real error */
- close(interpreter_fd);
- free(elf_phdata);
- return ~((abi_ulong)0UL);
- }
-
- if (!load_addr_set && interp_elf_ex->e_type == ET_DYN) {
- load_addr = error;
- load_addr_set = 1;
- }
-
- /*
- * Find the end of the file mapping for this phdr, and keep
- * track of the largest address we see for this.
- */
- k = load_addr + eppnt->p_vaddr + eppnt->p_filesz;
- if (k > elf_bss) elf_bss = k;
+ }
- /*
- * Do the same thing for the memory mapping - between
- * elf_bss and last_bss is the bss section.
- */
- k = load_addr + eppnt->p_memsz + eppnt->p_vaddr;
- if (k > last_bss) last_bss = k;
- }
+ error = load_elf_sections(interp_elf_ex, elf_phdata, interpreter_fd, rbase,
+ &baddr);
+ if (error != 0) {
+ perror("load_elf_sections");
+ exit(-1);
+ }
/* Now use mmap to map the library into memory. */
-
close(interpreter_fd);
-
- /*
- * Now fill out the bss section. First pad the last page up
- * to the page boundary, and then perform a mmap to make sure
- * that there are zeromapped pages up to and including the last
- * bss page.
- */
- padzero(elf_bss, last_bss);
- elf_bss = TARGET_ELF_PAGESTART(elf_bss + qemu_host_page_size - 1); /* What we have mapped so far */
-
- /* Map the last of the bss segment */
- if (last_bss > elf_bss) {
- target_mmap(elf_bss, last_bss - elf_bss,
- PROT_READ | PROT_WRITE | PROT_EXEC,
- MAP_FIXED | MAP_PRIVATE | MAP_ANON, -1, 0);
- }
free(elf_phdata);
- *interp_load_addr = load_addr;
- return ((abi_ulong) interp_elf_ex->e_entry) + load_addr;
+ *interp_load_addr = baddr;
+ return ((abi_ulong) interp_elf_ex->e_entry) + rbase;
}
static int symfind(const void *s0, const void *s1)
@@ -521,6 +457,10 @@ found:
}
continue;
}
+#if defined(TARGET_ARM) || defined(TARGET_MIPS)
+ /* The bottom address bit marks a Thumb or MIPS16 symbol. */
+ syms[i].st_value &= ~(target_ulong)1;
+#endif
i++;
}
@@ -560,26 +500,119 @@ found:
syminfos = s;
}
+/* Check the elf header and see if this a target elf binary. */
+int is_target_elf_binary(int fd)
+{
+ uint8_t buf[128];
+ struct elfhdr elf_ex;
+
+ if (lseek(fd, 0L, SEEK_SET) < 0) {
+ return 0;
+ }
+ if (read(fd, buf, sizeof(buf)) < 0) {
+ return 0;
+ }
+
+ elf_ex = *((struct elfhdr *)buf);
+ bswap_ehdr(&elf_ex);
+
+ if ((elf_ex.e_type != ET_EXEC && elf_ex.e_type != ET_DYN) ||
+ (!elf_check_arch(elf_ex.e_machine))) {
+ return 0;
+ } else {
+ return 1;
+ }
+}
+
+static int
+load_elf_sections(const struct elfhdr *hdr, struct elf_phdr *phdr, int fd,
+ abi_ulong rbase, abi_ulong *baddrp)
+{
+ struct elf_phdr *elf_ppnt;
+ abi_ulong baddr;
+ int i;
+ bool first;
+
+ /*
+ * Now we do a little grungy work by mmaping the ELF image into
+ * the correct location in memory. At this point, we assume that
+ * the image should be loaded at fixed address, not at a variable
+ * address.
+ */
+ first = true;
+ for (i = 0, elf_ppnt = phdr; i < hdr->e_phnum; i++, elf_ppnt++) {
+ int elf_prot = 0;
+ abi_ulong error;
+
+ /* XXX Skip memsz == 0. */
+ if (elf_ppnt->p_type != PT_LOAD) {
+ continue;
+ }
+
+ if (elf_ppnt->p_flags & PF_R) {
+ elf_prot |= PROT_READ;
+ }
+ if (elf_ppnt->p_flags & PF_W) {
+ elf_prot |= PROT_WRITE;
+ }
+ if (elf_ppnt->p_flags & PF_X) {
+ elf_prot |= PROT_EXEC;
+ }
+
+ error = target_mmap(TARGET_ELF_PAGESTART(rbase + elf_ppnt->p_vaddr),
+ (elf_ppnt->p_filesz +
+ TARGET_ELF_PAGEOFFSET(elf_ppnt->p_vaddr)),
+ elf_prot,
+ (MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE),
+ fd,
+ (elf_ppnt->p_offset -
+ TARGET_ELF_PAGEOFFSET(elf_ppnt->p_vaddr)));
+ if (error == -1) {
+ perror("mmap");
+ exit(-1);
+ } else if (elf_ppnt->p_memsz != elf_ppnt->p_filesz) {
+ abi_ulong start_bss, end_bss;
+
+ start_bss = rbase + elf_ppnt->p_vaddr + elf_ppnt->p_filesz;
+ end_bss = rbase + elf_ppnt->p_vaddr + elf_ppnt->p_memsz;
+
+ /*
+ * Calling set_brk effectively mmaps the pages that we need for the
+ * bss and break sections.
+ */
+ set_brk(start_bss, end_bss);
+ padzero(start_bss, end_bss);
+ }
+
+ if (first) {
+ baddr = TARGET_ELF_PAGESTART(rbase + elf_ppnt->p_vaddr);
+ first = false;
+ }
+ }
+
+ if (baddrp != NULL) {
+ *baddrp = baddr;
+ }
+ return 0;
+}
+
int load_elf_binary(struct bsd_binprm *bprm, struct target_pt_regs *regs,
struct image_info *info)
{
struct elfhdr elf_ex;
struct elfhdr interp_elf_ex;
int interpreter_fd = -1; /* avoid warning */
- abi_ulong load_addr, load_bias;
- int load_addr_set = 0;
+ abi_ulong load_addr;
int i;
- struct elf_phdr * elf_ppnt;
+ struct elf_phdr *elf_ppnt;
struct elf_phdr *elf_phdata;
- abi_ulong elf_bss, k, elf_brk;
- int retval;
- char * elf_interpreter;
- abi_ulong elf_entry, interp_load_addr = 0;
- abi_ulong start_code, end_code, start_data, end_data;
+ abi_ulong elf_brk;
+ int error, retval;
+ char *elf_interpreter;
+ abi_ulong baddr, elf_entry, et_dyn_addr, interp_load_addr = 0;
abi_ulong reloc_func_desc = 0;
load_addr = 0;
- load_bias = 0;
elf_ex = *((struct elfhdr *) bprm->buf); /* exec-header */
bswap_ehdr(&elf_ex);
@@ -618,16 +651,10 @@ int load_elf_binary(struct bsd_binprm *bprm, struct target_pt_regs *regs,
bswap_phdr(elf_phdata, elf_ex.e_phnum);
elf_ppnt = elf_phdata;
- elf_bss = 0;
elf_brk = 0;
elf_interpreter = NULL;
- start_code = ~((abi_ulong)0UL);
- end_code = 0;
- start_data = 0;
- end_data = 0;
-
for (i = 0; i < elf_ex.e_phnum; i++) {
if (elf_ppnt->p_type == PT_INTERP) {
if (elf_interpreter != NULL) {
@@ -714,94 +741,45 @@ int load_elf_binary(struct bsd_binprm *bprm, struct target_pt_regs *regs,
info->mmap = 0;
elf_entry = (abi_ulong) elf_ex.e_entry;
- /* Do this so that we can load the interpreter, if need be. We will
- change some of these later */
+ /* XXX Join this with PT_INTERP search? */
+ baddr = 0;
+ for (i = 0, elf_ppnt = elf_phdata; i < elf_ex.e_phnum; i++, elf_ppnt++) {
+ if (elf_ppnt->p_type != PT_LOAD) {
+ continue;
+ }
+ baddr = elf_ppnt->p_vaddr;
+ break;
+ }
+
+ et_dyn_addr = 0;
+ if (elf_ex.e_type == ET_DYN && baddr == 0) {
+ et_dyn_addr = ELF_ET_DYN_LOAD_ADDR;
+ }
+
+ /*
+ * Do this so that we can load the interpreter, if need be. We will
+ * change some of these later
+ */
info->rss = 0;
setup_arg_pages(bprm, info, &bprm->p, &bprm->stringp);
info->start_stack = bprm->p;
- /* Now we do a little grungy work by mmaping the ELF image into
- * the correct location in memory. At this point, we assume that
- * the image should be loaded at fixed address, not at a variable
- * address.
- */
+ info->elf_flags = elf_ex.e_flags;
+ error = load_elf_sections(&elf_ex, elf_phdata, bprm->fd, et_dyn_addr,
+ &load_addr);
for (i = 0, elf_ppnt = elf_phdata; i < elf_ex.e_phnum; i++, elf_ppnt++) {
- int elf_prot = 0;
- int elf_flags = 0;
- abi_ulong error;
-
- if (elf_ppnt->p_type != PT_LOAD)
+ if (elf_ppnt->p_type != PT_LOAD) {
continue;
-
- if (elf_ppnt->p_flags & PF_R) elf_prot |= PROT_READ;
- if (elf_ppnt->p_flags & PF_W) elf_prot |= PROT_WRITE;
- if (elf_ppnt->p_flags & PF_X) elf_prot |= PROT_EXEC;
- elf_flags = MAP_PRIVATE | MAP_DENYWRITE;
- if (elf_ex.e_type == ET_EXEC || load_addr_set) {
- elf_flags |= MAP_FIXED;
- } else if (elf_ex.e_type == ET_DYN) {
- /* Try and get dynamic programs out of the way of the default mmap
- base, as well as whatever program they might try to exec. This
- is because the brk will follow the loader, and is not movable. */
- /* NOTE: for qemu, we do a big mmap to get enough space
- without hardcoding any address */
- error = target_mmap(0, ET_DYN_MAP_SIZE,
- PROT_NONE, MAP_PRIVATE | MAP_ANON,
- -1, 0);
- if (error == -1) {
- perror("mmap");
- exit(-1);
- }
- load_bias = TARGET_ELF_PAGESTART(error - elf_ppnt->p_vaddr);
}
-
- error = target_mmap(TARGET_ELF_PAGESTART(load_bias + elf_ppnt->p_vaddr),
- (elf_ppnt->p_filesz +
- TARGET_ELF_PAGEOFFSET(elf_ppnt->p_vaddr)),
- elf_prot,
- (MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE),
- bprm->fd,
- (elf_ppnt->p_offset -
- TARGET_ELF_PAGEOFFSET(elf_ppnt->p_vaddr)));
- if (error == -1) {
- perror("mmap");
- exit(-1);
- }
-
- if (!load_addr_set) {
- load_addr_set = 1;
- load_addr = elf_ppnt->p_vaddr - elf_ppnt->p_offset;
- if (elf_ex.e_type == ET_DYN) {
- load_bias += error -
- TARGET_ELF_PAGESTART(load_bias + elf_ppnt->p_vaddr);
- load_addr += load_bias;
- reloc_func_desc = load_bias;
- }
- }
- k = elf_ppnt->p_vaddr;
- if (k < start_code)
- start_code = k;
- if (start_data < k)
- start_data = k;
- k = elf_ppnt->p_vaddr + elf_ppnt->p_filesz;
- if (k > elf_bss)
- elf_bss = k;
- if ((elf_ppnt->p_flags & PF_X) && end_code < k)
- end_code = k;
- if (end_data < k)
- end_data = k;
- k = elf_ppnt->p_vaddr + elf_ppnt->p_memsz;
- if (k > elf_brk) elf_brk = k;
- }
-
- elf_entry += load_bias;
- elf_bss += load_bias;
- elf_brk += load_bias;
- start_code += load_bias;
- end_code += load_bias;
- start_data += load_bias;
- end_data += load_bias;
+ if (elf_ppnt->p_memsz > elf_ppnt->p_filesz)
+ elf_brk = MAX(elf_brk, et_dyn_addr + elf_ppnt->p_vaddr +
+ elf_ppnt->p_memsz);
+ }
+ if (error != 0) {
+ perror("load_elf_sections");
+ exit(-1);
+ }
if (elf_interpreter) {
elf_entry = load_elf_interp(&interp_elf_ex, interpreter_fd,
@@ -817,6 +795,9 @@ int load_elf_binary(struct bsd_binprm *bprm, struct target_pt_regs *regs,
exit(-1);
return 0;
}
+ } else {
+ interp_load_addr = et_dyn_addr;
+ elf_entry += interp_load_addr;
}
free(elf_phdata);
@@ -829,20 +810,11 @@ int load_elf_binary(struct bsd_binprm *bprm, struct target_pt_regs *regs,
bprm->p = target_create_elf_tables(bprm->p, bprm->argc, bprm->envc,
bprm->stringp, &elf_ex, load_addr,
- load_bias, interp_load_addr, info);
+ et_dyn_addr, interp_load_addr, info);
info->load_addr = reloc_func_desc;
info->start_brk = info->brk = elf_brk;
- info->end_code = end_code;
- info->start_code = start_code;
- info->start_data = start_data;
- info->end_data = end_data;
info->start_stack = bprm->p;
-
- /* Calling set_brk effectively mmaps the pages that we need for the bss and break
- sections */
- set_brk(elf_bss, elf_brk);
-
- padzero(elf_bss, elf_brk);
+ info->load_bias = 0;
info->entry = elf_entry;
--
2.32.0
next prev parent reply other threads:[~2021-09-07 22:29 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-07 21:52 [PULL 00/42] bsd-user updates to run hello world imp
2021-09-07 21:52 ` [PULL 01/42] bsd-user: remove sparc and sparc64 imp
2021-09-07 21:52 ` [PULL 02/42] bsd-user: add copyright header to elfload.c imp
2021-09-07 21:52 ` [PULL 03/42] bsd-user: Add Stacey's copyright to main.c imp
2021-09-07 21:52 ` [PULL 04/42] bsd-user: add license to bsdload.c imp
2021-09-07 21:52 ` [PULL 05/42] bsd-user: style nits: bsdload.c whitespace to qemu standard imp
2021-09-07 21:52 ` [PULL 06/42] bsd-user: Remove all non-x86 code from elfload.c imp
2021-09-07 21:52 ` [PULL 07/42] bsd-user: move arch specific defines out of elfload.c imp
2021-09-07 21:52 ` [PULL 08/42] bsd-user: pass the bsd_param into loader_exec imp
2021-09-07 21:52 ` [PULL 09/42] bsd-user: Fix calculation of size to allocate imp
2021-09-07 21:53 ` [PULL 10/42] bsd-user: implement path searching imp
2021-09-07 21:53 ` [PULL 11/42] bsd-user: Eliminate elf personality imp
2021-09-07 21:53 ` [PULL 12/42] bsd-user: remove a.out support imp
2021-09-07 21:53 ` [PULL 13/42] bsd-user: TARGET_NGROUPS unused in this file, remove imp
2021-09-07 21:53 ` [PULL 14/42] bsd-user: elfload: simplify bswap a bit imp
2021-09-07 21:53 ` [PULL 15/42] bsd-user: assume pthreads and support of __thread imp
2021-09-07 21:53 ` [PULL 16/42] bsd-user: add host-os.h imp
2021-09-07 21:53 ` [PULL 17/42] bsd-user: Include host-os.h from main imp
2021-09-07 21:53 ` [PULL 18/42] bsd-user: save the path to the qemu emulator imp
2021-09-07 21:53 ` [PULL 19/42] bsd-user: start to move target CPU functions to target_arch* imp
2021-09-07 21:53 ` [PULL 20/42] bsd-user: Move per-cpu code into target_arch_cpu.h imp
2021-09-07 21:53 ` [PULL 21/42] bsd-user: pull in target_arch_thread.h update target_arch_elf.h imp
2021-09-07 21:53 ` [PULL 22/42] bsd-user: Include more things in qemu.h imp
2021-09-07 21:53 ` [PULL 23/42] bsd-user: define max args in terms of pages imp
2021-09-07 21:53 ` [PULL 24/42] bsd-user: Create target specific vmparam.h imp
2021-09-07 21:53 ` [PULL 25/42] bsd-user: Add system independent stack, data and text limiting imp
2021-09-07 21:53 ` [PULL 26/42] bsd-user: *BSD specific siginfo defintions imp
2021-09-07 21:53 ` [PULL 27/42] bsd-user: Implement --seed and initialize random state imp
2021-09-07 21:53 ` [PULL 28/42] bsd-user: Move stack initializtion into a per-os file imp
2021-09-07 21:53 ` [PULL 29/42] bsd-user: Add architecture specific signal tramp code imp
2021-09-07 21:53 ` [PULL 30/42] bsd-user: elf cleanup imp
2021-09-07 21:53 ` [PULL 31/42] bsd-user: Remove dead #ifdefs from elfload.c imp
2021-09-07 21:53 ` [PULL 32/42] bsd-user: Rewrite target system call definintion glue imp
2021-09-07 21:53 ` [PULL 33/42] bsd-user: update debugging in mmap.c imp
2021-09-07 21:53 ` [PULL 34/42] bsd-user: Add target_arch_reg to describe a target's register set imp
2021-09-07 21:53 ` [PULL 35/42] bsd-user: Add target_os_user.h to capture the user/kernel structures imp
2021-09-07 21:53 ` [PULL 36/42] bsd-user: add stubbed out core dump support imp
2021-09-07 21:53 ` [PULL 37/42] bsd-user: elfload.c style catch up patch imp
2021-09-07 21:53 ` imp [this message]
2021-09-07 21:53 ` [PULL 39/42] bsd-user: move gemu_log to later in the file imp
2021-09-07 21:53 ` [PULL 40/42] bsd-user: Implement interlock for atomic operations imp
2021-09-07 21:53 ` [PULL 41/42] bsd-user: Add '-0 argv0' option to bsd-user/main.c imp
2021-09-07 21:53 ` [PULL 42/42] bsd-user: Update mapping to handle reserved and starting conditions imp
2021-09-09 15:00 ` [PULL 00/42] bsd-user updates to run hello world Peter Maydell
2021-09-09 15:12 ` Warner Losh
2021-09-09 15:21 ` Daniel P. Berrangé
2021-09-09 16:31 ` Philippe Mathieu-Daudé
2021-09-10 20:35 ` Warner Losh
2021-09-09 16:29 ` Philippe Mathieu-Daudé
2021-09-10 20:31 ` Warner Losh
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