On Thu, Apr 7, 2011 at 10:29, Andreas Schwab <schwab@xxxxxxxxxxxxxx> wrote:
Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> writes:
Isn't there a reason it was read-write on m68k, like the table may be changed
at runtime (to install rootkits :-)? Have to check what the other arches do...
Initially the syscall_table in Linux has always been writable, bb152f53
("x86/x86_64: mark rodata section read-only: make some datastructures
const") made it read-only on x86. ÂApparently nobody bothered to do the
equivalent change on m68k (I don't think anything makes the kernel text
segment write protected anyway).
11 arches still store it in "data", including the 4 using the new
asm-generic/unistd.h
framework. 9 use "rodata" and 6 use "text".
The constness of C "extern" declarations doesn't necessarily matches the
actual sections.
alpha: .data
arm: presumably .text?
avr32: .section .rodata,"a",@progbits
blackfin: .section .l1.data / .data
cris: .section .rodata,"a"
frv: .section .rodata
h8300: .section .text
ia64: .rodata
extern unsigned long sys_call_table[NR_syscalls];
m32r: .section .rodata,"a"
m68k: .data (mmu), .text (nommu)
m68knommu: .text
microblaze: .section .rodata,"a"
mips: presumably .text?
mn10300: .data
extern const unsigned long sys_call_table[];
parisc: .section .rodata,"a"
powerpc: presumably .text?
extern unsigned long *sys_call_table;
static void *spu_syscall_table[] (SPU in CBEA)
s390: .section .rodata, "a"
extern const unsigned int sys_call_table[];
score: void *sys_call_table[__NR_syscalls[] = { ... }
sh: .data
extern const unsigned long sys_call_table[];
sh64: .section .data, "aw"
sparc: .data
extern const unsigned int sys_call_table[];
sparc64: .text
tile: void *sys_call_table[__NR_syscalls] = { ... }
void *compat_sys_call_table[__NR_syscalls] = { ... }
um: extern syscall_handler_t *sys_call_table[];
unicore32: void *sys_call_table[__NR_syscalls] = { ... }
x86: .section .rodata,"a"
extern const unsigned long sys_call_table[];
const sys_call_ptr_t
sys_call_table[__NR_syscall_max+1] = { ... }
xtensa: syscall_t sys_call_table[__NR_syscall_count] = { ... }
Gr{oetje,eeting}s,
            Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
             Â Â -- Linus Torvalds
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