Skip to contentSkip to conversation

casts in TLB macros

PATCH Applied Andrew Isaacson 3 participants 5 messages Aug 17, 2005 MIPS

lore
Share & tools
lore

Andrew Isaacson

author
#0 lore raw

PATCH 1/1 casts in TLB macros

Fix three cases where macro arguments are not parenthesized, leading to incorrect operator precedence when called with an expression as the argument. This causes incorrect evaluation of

    write_c0_entrylo0(pte_val(*ptep++) >> 6)

when pte_t is 64 bits - the pte value is cast to (unsigned int) first, then the shift is done, losing the top 32 bits.

Also, this does not add an extra set of parentheses surrounding the (cast)(value) pair, as there's no danger of precedence problems to avoid given the high precedence of the cast operator and that this is the terminal macro in this macro trail.

Signed-off-by Andrew Isaacson <[email protected]>
 include/asm-mips/pgtable-32.h |    2 +-
include/asm-mips/mipsregs.h +3 -3
Index: linux-2.6.13-rc5/include/asm-mips/mipsregs.h
===================================================================
@@ -693,13 +693,13 @@
 	if (sel == 0)							\
 		__asm__ __volatile__(					\
 			"mtc0\t%z0, " #register "\n\t"			\
-			: : "Jr" ((unsigned int)value));		\
+			: : "Jr" (unsigned int)(value));		\
 	else								\
 		__asm__ __volatile__(					\
 			".set\tmips32\n\t"				\
 			"mtc0\t%z0, " #register ", " #sel "\n\t"	\
 			".set\tmips0"					\
-			: : "Jr" ((unsigned int)value));		\
+			: : "Jr" (unsigned int)(value));		\
 } while (0)
 
 #define __write_64bit_c0_register(register, sel, value)			\

@@ -748,7 +748,7 @@
 do {									\
 	__asm__ __volatile__(						\
 		"ctc0\t%z0, " #register "\n\t"				\
-		: : "Jr" ((unsigned int)value));			\
+		: : "Jr" (unsigned int)(value));			\
 } while (0)
 
 /*
#1 lore raw

include/asm-mips/mipsregs.h line 754

Quoted 9 lines · Andrew Isaacson
include/asm-mips/mipsregs.h +1 -1
@@ -748,7 +748,7 @@
 do {									\
 	__asm__ __volatile__(						\
 		"ctc0\t%z0, " #register "\n\t"				\
-		: : "Jr" ((unsigned int)value));			\
+		: : "Jr" (unsigned int)(value));			\
 } while (0)
 
 /*

I'm surprised it works, but please don't drop the outer brackets in asm
operands anyway. Otherwise it's an obvious fix, thanks.

Maciej

Applied
#2 lore raw
In reply to Andrew Isaacson
Quoted 11 lines · Andrew Isaacson

Fix three cases where macro arguments are not parenthesized, leading to incorrect operator precedence when called with an expression as the argument. This causes incorrect evaluation of

    write_c0_entrylo0(pte_val(*ptep++) >> 6)

when pte_t is 64 bits - the pte value is cast to (unsigned int) first, then the shift is done, losing the top 32 bits.

Also, this does not add an extra set of parentheses surrounding the (cast)(value) pair, as there's no danger of precedence problems to avoid given the high precedence of the cast operator and that this is the terminal macro in this macro trail.

Thanks, applied,

Ralf

author
#3 lore raw
Quoted 9 lines · Ralf Baechle
Quoted 7 lines · Andrew Isaacson

Fix three cases where macro arguments are not parenthesized, leading to incorrect operator precedence when called with an expression as the argument. This causes incorrect evaluation of

    write_c0_entrylo0(pte_val(*ptep++) >> 6)

when pte_t is 64 bits - the pte value is cast to (unsigned int) first, then the shift is done, losing the top 32 bits.

Quoted 6 lines
Quoted 4 lines

Also, this does not add an extra set of parentheses surrounding the (cast)(value) pair, as there's no danger of precedence problems to avoid given the high precedence of the cast operator and that this is the terminal macro in this macro trail.

Thanks, applied,

Thank *you* for being smarter than me about the parenthesis...

(The patch I sent out was lacking the outer parens, and I used the following plan for world domination:
1. notice problem, cut patch
2. go to dinner
3. test compile something unrelated by accident
4. send patch to mailing list
5. profit!)

-andy

#4 lore raw
Quoted 7 lines · Andrew Isaacson

(The patch I sent out was lacking the outer parens, and I used the following plan for world domination:
1. notice problem, cut patch
2. go to dinner
3. test compile something unrelated by accident
4. send patch to mailing list
5. profit!)

5) reminds me of Clausen Profit System Online, see
http://members.optusnet.com.au/clausen/profit/

Ralf