mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-15 17:28:15 +00:00
54841ab50c
The hush shell dynamically allocates (and re-allocates) memory for the
argument strings in the "char *argv[]" argument vector passed to
commands. Any code that modifies these pointers will cause serious
corruption of the malloc data structures and crash U-Boot, so make
sure the compiler can check that no such modifications are being done
by changing the code into "char * const argv[]".
This modification is the result of debugging a strange crash caused
after adding a new command, which used the following argument
processing code which has been working perfectly fine in all Unix
systems since version 6 - but not so in U-Boot:
int main (int argc, char **argv)
{
while (--argc > 0 && **++argv == '-') {
/* ====> */ while (*++*argv) {
switch (**argv) {
case 'd':
debug++;
break;
...
default:
usage ();
}
}
}
...
}
The line marked "====>" will corrupt the malloc data structures and
usually cause U-Boot to crash when the next command gets executed by
the shell. With the modification, the compiler will prevent this with
an
error: increment of read-only location '*argv'
N.B.: The code above can be trivially rewritten like this:
while (--argc > 0 && **++argv == '-') {
char *arg = *argv;
while (*++arg) {
switch (*arg) {
...
Signed-off-by: Wolfgang Denk <wd@denx.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
208 lines
5.4 KiB
C
208 lines
5.4 KiB
C
#include <exports.h>
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#ifndef GCC_VERSION
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#define GCC_VERSION (__GNUC__ * 1000 + __GNUC_MINOR__)
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#endif /* GCC_VERSION */
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#if defined(CONFIG_I386)
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/*
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* x86 does not have a dedicated register to store the pointer to
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* the global_data. Thus the jump table address is stored in a
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* global variable, but such approach does not allow for execution
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* from flash memory. The global_data address is passed as argv[-1]
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* to the application program.
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*/
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static void **jt;
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gd_t *global_data;
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#define EXPORT_FUNC(x) \
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asm volatile ( \
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" .globl " #x "\n" \
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#x ":\n" \
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" movl %0, %%eax\n" \
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" movl jt, %%ecx\n" \
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" jmp *(%%ecx, %%eax)\n" \
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: : "i"(XF_ ## x * sizeof(void *)) : "eax", "ecx");
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#elif defined(CONFIG_PPC)
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/*
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* r2 holds the pointer to the global_data, r11 is a call-clobbered
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* register
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*/
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#define EXPORT_FUNC(x) \
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asm volatile ( \
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" .globl " #x "\n" \
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#x ":\n" \
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" lwz %%r11, %0(%%r2)\n" \
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" lwz %%r11, %1(%%r11)\n" \
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" mtctr %%r11\n" \
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" bctr\n" \
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: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r11");
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#elif defined(CONFIG_ARM)
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/*
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* r8 holds the pointer to the global_data, ip is a call-clobbered
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* register
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*/
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#define EXPORT_FUNC(x) \
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asm volatile ( \
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" .globl " #x "\n" \
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#x ":\n" \
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" ldr ip, [r8, %0]\n" \
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" ldr pc, [ip, %1]\n" \
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: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "ip");
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#elif defined(CONFIG_MIPS)
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/*
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* k0 ($26) holds the pointer to the global_data; t9 ($25) is a call-
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* clobbered register that is also used to set gp ($26). Note that the
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* jr instruction also executes the instruction immediately following
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* it; however, GCC/mips generates an additional `nop' after each asm
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* statement
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*/
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#define EXPORT_FUNC(x) \
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asm volatile ( \
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" .globl " #x "\n" \
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#x ":\n" \
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" lw $25, %0($26)\n" \
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" lw $25, %1($25)\n" \
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" jr $25\n" \
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: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "t9");
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#elif defined(CONFIG_NIOS2)
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/*
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* gp holds the pointer to the global_data, r8 is call-clobbered
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*/
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#define EXPORT_FUNC(x) \
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asm volatile ( \
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" .globl " #x "\n" \
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#x ":\n" \
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" movhi r8, %%hi(%0)\n" \
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" ori r8, r0, %%lo(%0)\n" \
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" add r8, r8, gp\n" \
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" ldw r8, 0(r8)\n" \
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" ldw r8, %1(r8)\n" \
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" jmp r8\n" \
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: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "gp");
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#elif defined(CONFIG_M68K)
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/*
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* d7 holds the pointer to the global_data, a0 is a call-clobbered
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* register
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*/
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#define EXPORT_FUNC(x) \
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asm volatile ( \
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" .globl " #x "\n" \
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#x ":\n" \
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" move.l %%d7, %%a0\n" \
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" adda.l %0, %%a0\n" \
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" move.l (%%a0), %%a0\n" \
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" adda.l %1, %%a0\n" \
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" move.l (%%a0), %%a0\n" \
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" jmp (%%a0)\n" \
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: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "a0");
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#elif defined(CONFIG_MICROBLAZE)
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/*
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* r31 holds the pointer to the global_data. r5 is a call-clobbered.
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*/
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#define EXPORT_FUNC(x) \
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asm volatile ( \
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" .globl " #x "\n" \
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#x ":\n" \
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" lwi r5, r31, %0\n" \
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" lwi r5, r5, %1\n" \
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" bra r5\n" \
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: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r5");
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#elif defined(CONFIG_BLACKFIN)
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/*
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* P3 holds the pointer to the global_data, P0 is a call-clobbered
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* register
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*/
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#define EXPORT_FUNC(x) \
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asm volatile ( \
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" .globl _" #x "\n_" \
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#x ":\n" \
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" P0 = [P3 + %0]\n" \
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" P0 = [P0 + %1]\n" \
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" JUMP (P0)\n" \
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: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "P0");
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#elif defined(CONFIG_AVR32)
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/*
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* r6 holds the pointer to the global_data. r8 is call clobbered.
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*/
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#define EXPORT_FUNC(x) \
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asm volatile( \
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" .globl\t" #x "\n" \
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#x ":\n" \
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" ld.w r8, r6[%0]\n" \
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" ld.w pc, r8[%1]\n" \
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: \
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: "i"(offsetof(gd_t, jt)), "i"(XF_ ##x) \
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: "r8");
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#elif defined(CONFIG_SH)
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/*
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* r13 holds the pointer to the global_data. r1 is a call clobbered.
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*/
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#define EXPORT_FUNC(x) \
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asm volatile ( \
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" .align 2\n" \
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" .globl " #x "\n" \
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#x ":\n" \
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" mov r13, r1\n" \
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" add %0, r1\n" \
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" mov.l @r1, r2\n" \
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" add %1, r2\n" \
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" mov.l @r2, r1\n" \
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" jmp @r1\n" \
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" nop\n" \
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" nop\n" \
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: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r1", "r2");
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#elif defined(CONFIG_SPARC)
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/*
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* g7 holds the pointer to the global_data. g1 is call clobbered.
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*/
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#define EXPORT_FUNC(x) \
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asm volatile( \
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" .globl\t" #x "\n" \
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#x ":\n" \
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" set %0, %%g1\n" \
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" or %%g1, %%g7, %%g1\n" \
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" ld [%%g1], %%g1\n" \
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" ld [%%g1 + %1], %%g1\n" \
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" jmp %%g1\n" \
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" nop\n" \
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: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "g1" );
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#else
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#error stubs definition missing for this architecture
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#endif
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/* This function is necessary to prevent the compiler from
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* generating prologue/epilogue, preparing stack frame etc.
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* The stub functions are special, they do not use the stack
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* frame passed to them, but pass it intact to the actual
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* implementation. On the other hand, asm() statements with
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* arguments can be used only inside the functions (gcc limitation)
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*/
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#if GCC_VERSION < 3004
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static
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#endif /* GCC_VERSION */
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void __attribute__((unused)) dummy(void)
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{
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#include <_exports.h>
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}
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extern unsigned long __bss_start, _end;
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void app_startup(char * const *argv)
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{
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unsigned char * cp = (unsigned char *) &__bss_start;
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/* Zero out BSS */
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while (cp < (unsigned char *)&_end) {
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*cp++ = 0;
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}
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#if defined(CONFIG_I386)
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/* x86 does not have a dedicated register for passing global_data */
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global_data = (gd_t *)argv[-1];
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jt = global_data->jt;
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#endif
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}
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#undef EXPORT_FUNC
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