@@ -112,6 +112,9 @@ config BINFMT_FLAT_ARGVP_ENVP_ON_STACK
config BINFMT_FLAT_OLD_ALWAYS_RAM
bool
+config BINFMT_FLAT_NO_TEXT_DATA_GAP
+ bool
+
config BINFMT_FLAT_OLD
bool "Enable support for very old legacy flat binaries"
depends on BINFMT_FLAT
@@ -74,6 +74,12 @@
#define MAX_SHARED_LIBS (1)
#endif
+#ifdef CONFIG_BINFMT_FLAT_NO_TEXT_DATA_GAP
+#define DATA_GAP_WORDS (0)
+#else
+#define DATA_GAP_WORDS (MAX_SHARED_LIBS)
+#endif
+
struct lib_info {
struct {
unsigned long start_code; /* Start of text segment */
@@ -559,7 +565,10 @@ static int load_flat_file(struct linux_binprm *bprm,
* case, and then the fully copied to RAM case which lumps
* it all together.
*/
- if (!IS_ENABLED(CONFIG_MMU) && !(flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP))) {
+ if (!IS_ENABLED(CONFIG_MMU) &&
+ !IS_ENABLED(CONFIG_BINFMT_FLAT_NO_TEXT_DATA_GAP) &&
+ !(flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP))) {
+
/*
* this should give us a ROM ptr, but if it doesn't we don't
* really care
@@ -576,7 +585,7 @@ static int load_flat_file(struct linux_binprm *bprm,
goto err;
}
- len = data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
+ len = data_len + extra + DATA_GAP_WORDS * sizeof(unsigned long);
len = PAGE_ALIGN(len);
realdatastart = vm_mmap(NULL, 0, len,
PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, 0);
@@ -591,7 +600,7 @@ static int load_flat_file(struct linux_binprm *bprm,
goto err;
}
datapos = ALIGN(realdatastart +
- MAX_SHARED_LIBS * sizeof(unsigned long),
+ DATA_GAP_WORDS * sizeof(unsigned long),
FLAT_DATA_ALIGN);
pr_debug("Allocated data+bss+stack (%u bytes): %lx\n",
@@ -622,7 +631,7 @@ static int load_flat_file(struct linux_binprm *bprm,
memp_size = len;
} else {
- len = text_len + data_len + extra + MAX_SHARED_LIBS * sizeof(u32);
+ len = text_len + data_len + extra + DATA_GAP_WORDS * sizeof(u32);
len = PAGE_ALIGN(len);
textpos = vm_mmap(NULL, 0, len,
PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE, 0);
@@ -638,7 +647,7 @@ static int load_flat_file(struct linux_binprm *bprm,
realdatastart = textpos + ntohl(hdr->data_start);
datapos = ALIGN(realdatastart +
- MAX_SHARED_LIBS * sizeof(u32),
+ DATA_GAP_WORDS * sizeof(u32),
FLAT_DATA_ALIGN);
reloc = (__be32 __user *)
@@ -714,7 +723,7 @@ static int load_flat_file(struct linux_binprm *bprm,
ret = result;
pr_err("Unable to read code+data+bss, errno %d\n", ret);
vm_munmap(textpos, text_len + data_len + extra +
- MAX_SHARED_LIBS * sizeof(u32));
+ DATA_GAP_WORDS * sizeof(u32));
goto err;
}
}
Commit 2217b9826246 ("binfmt_flat: revert "binfmt_flat: don't offset the data start"") restored offsetting the start of the data section by a number of words defined by MAX_SHARED_LIBS. As a result, since MAX_SHARED_LIBS is never 0, a gap between the text and data sections always exists. For architectures which cannot support a such gap between the text and data sections (e.g. riscv nommu), flat binary programs cannot be executed. To allow an architecture to request contiguous text and data sections, introduce the config option CONFIG_BINFMT_FLAT_NO_TEXT_DATA_GAP. Using this new option, the macro DATA_GAP_WORDS is conditionally defined in binfmt_flat.c to MAX_SHARED_LIBS for architectures tolerating the text-to-data gap (CONFIG_BINFMT_FLAT_NO_TEXT_DATA_GAP disabled case) and to 0 when CONFIG_BINFMT_FLAT_NO_TEXT_DATA_GAP is enabled. DATA_GAP_WORDS is used in load_flat_file() to calculate the data section length and start position. An architecture enabling CONFIG_BINFMT_FLAT_NO_TEXT_DATA_GAP also prevents the use of the separate text/data load case (when the flat file header flags FLAT_FLAG_RAM and FLAT_FLAG_GZIP are not set with NOMMU kernels) and forces the use of a single RAM region for loading (equivalent to FLAT_FLAG_RAM being set). Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> --- fs/Kconfig.binfmt | 3 +++ fs/binfmt_flat.c | 21 +++++++++++++++------ 2 files changed, 18 insertions(+), 6 deletions(-)