From 26a9a418237c0b06528941bca693c49c8d97edbe Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 19 May 2009 11:25:35 -0700 Subject: [PATCH] Avoid ICE in get_random_int() with gcc-3.4.5 Martin Knoblauch reports that trying to build 2.6.30-rc6-git3 with RHEL4.3 userspace (gcc (GCC) 3.4.5 20051201 (Red Hat 3.4.5-2)) causes an internal compiler error (ICE): drivers/char/random.c: In function `get_random_int': drivers/char/random.c:1672: error: unrecognizable insn: (insn 202 148 150 0 /scratch/build/linux-2.6.30-rc6-git3/arch/x86/include/asm/tsc.h:23 (set (reg:SI 0 ax [91]) (subreg:SI (plus:DI (plus:DI (reg:DI 0 ax [88]) (subreg:DI (reg:SI 6 bp) 0)) (const_int -4 [0xfffffffffffffffc])) 0)) -1 (nil) (nil)) drivers/char/random.c:1672: internal compiler error: in extract_insn, at recog.c:2083 and after some debugging it turns out that it's due to the code trying to figure out the rough value of the current stack pointer by taking an address of an uninitialized variable and casting that to an integer. This is clearly a compiler bug, but it's not worth fighting - while the current stack kernel pointer might be somewhat hard to predict in user space, it's also not generally going to change for a lot of the call chains for a particular process. So just drop it, and mumble some incoherent curses at the compiler. Tested-by: Martin Knoblauch Cc: Matt Mackall Cc: Ingo Molnar Signed-off-by: Linus Torvalds --- drivers/char/random.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index b2ced39d76b2..8c7444857a4b 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1673,7 +1673,7 @@ unsigned int get_random_int(void) int ret; keyptr = get_keyptr(); - hash[0] += current->pid + jiffies + get_cycles() + (int)(long)&ret; + hash[0] += current->pid + jiffies + get_cycles(); ret = half_md4_transform(hash, keyptr->secret); put_cpu_var(get_random_int_hash); -- 2.39.5