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author | Trent Piepho <tpiepho@kymetacorp.com> | 2015-12-03 01:24:56 +0000 |
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committer | Sascha Hauer <s.hauer@pengutronix.de> | 2015-12-04 08:15:23 +0100 |
commit | de7a09bb4326fd9f014303a45e3ad5a729ac3a3c (patch) | |
tree | 89a1af10769eac300fdae00b1928991cfab1cd1f /arch/arm/lib | |
parent | acc017737f8ec65740be798e8daea257eb86f0aa (diff) | |
download | barebox-de7a09bb4326fd9f014303a45e3ad5a729ac3a3c.tar.gz barebox-de7a09bb4326fd9f014303a45e3ad5a729ac3a3c.tar.xz |
ARM: Remove kernel booting call for thumb2 mode
The asm code to do the actual call into the kernel (or another
barebox) when compiled in thumb2 mode isn't necessary. gcc generates
a perfectly good calling sequence from a normal function pointer call.
If it didn't, the code in bootstrap_boot() that uses a function
pointer to jump to the 2nd stage barebox from an xloader wouldn't
work.
It appears to be allowed that the call to kernel() could return, as
neither start_linux() nor kernel() are marked noreturn, and there is
code after calls to start_linux().
The asm code has a bug in this case, as it uses bx and not blx, and
thus doesn't set the link register. Since it's a tail call, this
would be okay, but only if the LR value from the start of
start_linux() (and the callee-saved registers) are restored
beforehand, which isn't done. The gcc generated call sequence will do
this.
Signed-off-by: Trent Piepho <tpiepho@kymetacorp.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'arch/arm/lib')
-rw-r--r-- | arch/arm/lib/armlinux.c | 12 |
1 files changed, 0 insertions, 12 deletions
diff --git a/arch/arm/lib/armlinux.c b/arch/arm/lib/armlinux.c index 16879f8e59..47b9bd33ed 100644 --- a/arch/arm/lib/armlinux.c +++ b/arch/arm/lib/armlinux.c @@ -277,17 +277,5 @@ void start_linux(void *adr, int swap, unsigned long initrd_address, __asm__ __volatile__("mcr p15, 0, %0, c1, c0" :: "r" (reg)); } -#ifdef CONFIG_THUMB2_BAREBOX - __asm__ __volatile__ ( - "mov r0, #0\n" - "mov r1, %0\n" - "mov r2, %1\n" - "bx %2\n" - : - : "r" (architecture), "r" (params), "r" (kernel) - : "r0", "r1", "r2" - ); -#else kernel(0, architecture, params); -#endif } |