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xtensa_sim_console: fix simcall

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simcall must be in the volatile asm so that gcc does not optimize it
out. It also needs "memory" clobber to make sure data passed through
memory buffer is actually written back before the simcall.

Change-Id: I410b7348bf605d0d08f81ec5395f6cb144f33a43
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
This commit is contained in:
Max Filippov 2017-02-15 13:55:48 -08:00 • committed by Andrew Boie
commit 0ad868a58c
1 changed files with 3 additions and 2 deletions
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5
drivers/console/xtensa_sim_console.c
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@ -25,9 +25,10 @@ static int console_out(int c)
register int ret_err __asm__ ("a3"); register int ret_err __asm__ ("a3");
buf[0] = (char)c; buf[0] = (char)c;
__asm__ ("simcall" __asm__ volatile ("simcall"
: "=a" (ret_val), "=a" (ret_err) : "=a" (ret_val), "=a" (ret_err)
: "a" (a2), "a" (a3), "a" (a4), "a" (a5)); : "a" (a2), "a" (a3), "a" (a4), "a" (a5)
: "memory");
return c; return c;
} }
#endif #endif