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sh: boot kernel with SR.BL set

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Update the SH kernel to keep SR.BL set until the VBR
register has been initialized. Useful to allow boot
of the kernel even though exceptions are pending.

Without this patch there is a window of time when
exceptions such as NMI are enabled but no exception
handlers are installed.

This patch modifies both the zImage loader and the
actual kernel to boot with BL=1, but the zImage
loader is modfied in such a way that the init_sr
value is unchanged to not break the zImage loader
provided by kexec.

Tested on sh7724 Ecovec and on the SH4AL-DSP core
included in sh7372.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Magnus Damm 2010-09-24 09:05:38 +00:00 committed by Paul Mundt
parent 4c62c595c2
commit 68a1aed703
3 changed files with 7 additions and 2 deletions
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4
arch/sh/boot/compressed/head_32.S
View File

@ -91,7 +91,9 @@ bss_start_addr:
end_addr:
.long _end
init_sr:
.long 0x400000F0 /* Privileged mode, Bank=0, Block=0, IMASK=0xF */
.long 0x500000F0 /* Privileged mode, Bank=0, Block=1, IMASK=0xF */
kexec_magic:
.long 0x400000F0 /* magic used by kexec to parse zImage format */
init_stack_addr:
.long stack_start
decompress_kernel_addr:

2
arch/sh/kernel/head_32.S
View File

@ -330,7 +330,7 @@ ENTRY(_stext)
#if defined(CONFIG_CPU_SH2)
1: .long 0x000000F0 ! IMASK=0xF
#else
1: .long 0x400080F0 ! MD=1, RB=0, BL=0, FD=1, IMASK=0xF
1: .long 0x500080F0 ! MD=1, RB=0, BL=1, FD=1, IMASK=0xF
#endif
ENTRY(stack_start)
2: .long init_thread_union+THREAD_SIZE

3
arch/sh/kernel/traps_32.c
View File

@ -802,6 +802,9 @@ void __cpuinit per_cpu_trap_init(void)
: /* no output */
: "r" (&vbr_base)
: "memory");
/* disable exception blocking now when the vbr has been setup */
clear_bl_bit();
}
void *set_exception_table_vec(unsigned int vec, void *handler)