Commit 882136fb authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/32s: Simplify calculation of segment register content 



segment register has VSID on bits 8-31.
Bits 4-7 are reserved, there is no requirement to set them to 0.

VSIDs are calculated from VSID of SR0 by adding 0x111.

Even with highest possible VSID which would be 0xFFFFF0,
adding 16 times 0x111 results in 0x1001100.

So, the reserved bits are never overflowed, no need to clear
the reserved bits after each calculation.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/ddc1cfd2ec8f3b2395c6a4d7f2b0c1aa1b1e64fb.1622708530.git.christophe.leroy@csgroup.eu
parent 863771a2

arch/powerpc/include/asm/book3s/32/mmu-hash.h

+23 −19
Original line number Diff line number Diff line
@@ -115,28 +115,32 @@ extern s32 patch__flush_hash_B; 
#include <asm/reg.h>

#include <asm/task_size_32.h>



#define UPDATE_TWO_USER_SEGMENTS(n) do {		\

	if (TASK_SIZE > ((n) << 28))			\

		mtsr(val1, (n) << 28);			\

	if (TASK_SIZE > (((n) + 1) << 28))		\

		mtsr(val2, ((n) + 1) << 28);		\

	val1 = (val1 + 0x222) & 0xf0ffffff;		\

	val2 = (val2 + 0x222) & 0xf0ffffff;		\

} while (0)

static __always_inline void update_user_segment(u32 n, u32 val)

{

	if (n << 28 < TASK_SIZE)

		mtsr(val + n * 0x111, n << 28);

}



static __always_inline void update_user_segments(u32 val)

{

	int val1 = val;

	int val2 = (val + 0x111) & 0xf0ffffff;



	UPDATE_TWO_USER_SEGMENTS(0);

	UPDATE_TWO_USER_SEGMENTS(2);

	UPDATE_TWO_USER_SEGMENTS(4);

	UPDATE_TWO_USER_SEGMENTS(6);

	UPDATE_TWO_USER_SEGMENTS(8);

	UPDATE_TWO_USER_SEGMENTS(10);

	UPDATE_TWO_USER_SEGMENTS(12);

	UPDATE_TWO_USER_SEGMENTS(14);

	val &= 0xf0ffffff;



	update_user_segment(0, val);

	update_user_segment(1, val);

	update_user_segment(2, val);

	update_user_segment(3, val);

	update_user_segment(4, val);

	update_user_segment(5, val);

	update_user_segment(6, val);

	update_user_segment(7, val);

	update_user_segment(8, val);

	update_user_segment(9, val);

	update_user_segment(10, val);

	update_user_segment(11, val);

	update_user_segment(12, val);

	update_user_segment(13, val);

	update_user_segment(14, val);

	update_user_segment(15, val);

}



#endif /* !__ASSEMBLY__ */