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Subject[PATCH v4 11/12] binfmt_flat: add MMU-specific support
Date
Not much else to do at this point except for the different stack setups.

SuperH and Xtensa could be added to the allowed list if they implement
__put_user_unaligned() and __get_user_unaligned().

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
fs/Kconfig.binfmt | 3 ++-
fs/binfmt_flat.c | 16 +++++++++++++---
2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index 72c03354c1..4c09d93d95 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -89,7 +89,8 @@ config BINFMT_SCRIPT

config BINFMT_FLAT
bool "Kernel support for flat binaries"
- depends on !MMU && (!FRV || BROKEN)
+ depends on !MMU || ARM || M68K
+ depends on !FRV || BROKEN
help
Support uClinux FLAT format binaries.

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index aa7971ce6a..7b999aebad 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -537,7 +537,7 @@ static int load_flat_file(struct linux_binprm *bprm,
* case, and then the fully copied to RAM case which lumps
* it all together.
*/
- if ((flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP)) == 0) {
+ if (!IS_ENABLED(CONFIG_MMU) && !(flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP))) {
/*
* this should give us a ROM ptr, but if it doesn't we don't
* really care
@@ -677,7 +677,9 @@ static int load_flat_file(struct linux_binprm *bprm,
*/
current->mm->start_brk = datapos + data_len + bss_len;
current->mm->brk = (current->mm->start_brk + 3) & ~3;
+#ifndef CONFIG_MMU
current->mm->context.end_brk = memp + memp_size - stack_len;
+#endif
}

if (flags & FLAT_FLAG_KTRACE) {
@@ -870,7 +872,7 @@ static int load_flat_binary(struct linux_binprm *bprm)
{
struct lib_info libinfo;
struct pt_regs *regs = current_pt_regs();
- unsigned long stack_len;
+ unsigned long stack_len = 0;
unsigned long start_addr;
int res;
int i, j;
@@ -884,7 +886,9 @@ static int load_flat_binary(struct linux_binprm *bprm)
* pedantic and include space for the argv/envp array as it may have
* a lot of entries.
*/
- stack_len = PAGE_SIZE * MAX_ARG_PAGES - bprm->p; /* the strings */
+#ifndef CONFIG_MMU
+ stack_len += PAGE_SIZE * MAX_ARG_PAGES - bprm->p; /* the strings */
+#endif
stack_len += (bprm->argc + 1) * sizeof(char *); /* the argv array */
stack_len += (bprm->envc + 1) * sizeof(char *); /* the envp array */
stack_len = ALIGN(stack_len, FLAT_STACK_ALIGN);
@@ -912,6 +916,11 @@ static int load_flat_binary(struct linux_binprm *bprm)

set_binfmt(&flat_format);

+#ifdef CONFIG_MMU
+ res = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
+ if (!res)
+ res = create_flat_tables(bprm, bprm->p);
+#else
/* Stash our initial stack pointer into the mm structure */
current->mm->start_stack =
((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
@@ -921,6 +930,7 @@ static int load_flat_binary(struct linux_binprm *bprm)
res = transfer_args_to_stack(bprm, &current->mm->start_stack);
if (!res)
res = create_flat_tables(bprm, current->mm->start_stack);
+#endif
if (res)
return res;

--
2.7.4
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