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Commit 3fd3a74f authored by Carlos O'Donell's avatar Carlos O'Donell Committed by Kyle McMartin
Browse files

[PARISC] Use FIXUP_BRANCH_CLOBBER to asm clobber list 



Joel Soete noticed correctly that the fixup's clobbers must be listed
as the ASM clobbers. FIXUP_BRANCH in unaligned.c has a new macro which
lists all the clobbers in the fixup, we use this throughout the file
to simplify the process of listing clobbers in the future.

A missing "r1" clobber is added to our uaccess.h for the 64-bit
__put_kernel_asm. Interestingly this is a pretty serious bug since gcc
generates pretty good use of r1 as a temporary and the uses of
__put_kernel_asm are varied and dangerous if r1 is scratched during
an invalid write.

Signed-off-by: default avatarJoel Soete <soete.joel@tiscali.be>
Signed-off-by: default avatarCarlos O'Donell <carlos@parisc-linux.org>
Signed-off-by: default avatarKyle McMartin <kyle@parisc-linux.org>
parent c8224e00

arch/parisc/kernel/unaligned.c

+10 −8
Original line number Diff line number Diff line
@@ -43,6 +43,8 @@ 
	"\tldil L%%" #lbl ", %%r1\n"			\

	"\tldo R%%" #lbl "(%%r1), %%r1\n"		\

	"\tbv,n %%r0(%%r1)\n"

/* If you use FIXUP_BRANCH, then you must list this clobber */

#define FIXUP_BRANCH_CLOBBER "r1"



/* 1111 1100 0000 0000 0001 0011 1100 0000 */

#define OPCODE1(a,b,c)	((a)<<26|(b)<<12|(c)<<6)
@@ -157,7 +159,7 @@ static int emulate_ldh(struct pt_regs *regs, int toreg) 
"	.previous\n"

	: "=r" (val), "=r" (ret)

	: "0" (val), "r" (saddr), "r" (regs->isr)

	: "r20" );

	: "r20", FIXUP_BRANCH_CLOBBER );



	DPRINTF("val = 0x" RFMT "\n", val);
@@ -202,7 +204,7 @@ static int emulate_ldw(struct pt_regs *regs, int toreg, int flop) 
"	.previous\n"

	: "=r" (val), "=r" (ret)

	: "0" (val), "r" (saddr), "r" (regs->isr)

	: "r19", "r20" );

	: "r19", "r20", FIXUP_BRANCH_CLOBBER );



	DPRINTF("val = 0x" RFMT "\n", val);
@@ -253,7 +255,7 @@ static int emulate_ldd(struct pt_regs *regs, int toreg, int flop) 
"	.previous\n"

	: "=r" (val), "=r" (ret)

	: "0" (val), "r" (saddr), "r" (regs->isr)

	: "r19", "r20" );

	: "r19", "r20", FIXUP_BRANCH_CLOBBER );

#else

    {

	unsigned long valh=0,vall=0;
@@ -287,7 +289,7 @@ static int emulate_ldd(struct pt_regs *regs, int toreg, int flop) 
"	.previous\n"

	: "=r" (valh), "=r" (vall), "=r" (ret)

	: "0" (valh), "1" (vall), "r" (saddr), "r" (regs->isr)

	: "r19", "r20" );

	: "r19", "r20", FIXUP_BRANCH_CLOBBER );

	val=((__u64)valh<<32)|(__u64)vall;

    }

#endif
@@ -335,7 +337,7 @@ static int emulate_sth(struct pt_regs *regs, int frreg) 
"	.previous\n"

	: "=r" (ret)

	: "r" (val), "r" (regs->ior), "r" (regs->isr)

	: "r19" );

	: "r19", FIXUP_BRANCH_CLOBBER );



	return ret;

}
@@ -389,7 +391,7 @@ static int emulate_stw(struct pt_regs *regs, int frreg, int flop) 
"	.previous\n"

	: "=r" (ret)

	: "r" (val), "r" (regs->ior), "r" (regs->isr)

	: "r19", "r20", "r21", "r22", "r1" );

	: "r19", "r20", "r21", "r22", "r1", FIXUP_BRANCH_CLOBBER );



	return 0;

}
@@ -450,7 +452,7 @@ static int emulate_std(struct pt_regs *regs, int frreg, int flop) 
"	.previous\n"

	: "=r" (ret)

	: "r" (val), "r" (regs->ior), "r" (regs->isr)

	: "r19", "r20", "r21", "r22", "r1" );

	: "r19", "r20", "r21", "r22", "r1", FIXUP_BRANCH_CLOBBER );

#else

    {

	unsigned long valh=(val>>32),vall=(val&0xffffffffl);
@@ -495,7 +497,7 @@ static int emulate_std(struct pt_regs *regs, int frreg, int flop) 
"	.previous\n"

	: "=r" (ret)

	: "r" (valh), "r" (vall), "r" (regs->ior), "r" (regs->isr)

	: "r19", "r20", "r21", "r1" );

	: "r19", "r20", "r21", "r1", FIXUP_BRANCH_CLOBBER );

    }

#endif

include/asm-parisc/uaccess.h

+7 −2
Original line number Diff line number Diff line
@@ -172,7 +172,11 @@ struct exception_data { 
/*

 * The "__put_user/kernel_asm()" macros tell gcc they read from memory

 * instead of writing. This is because they do not write to any memory

 * gcc knows about, so there are no aliasing issues.

 * gcc knows about, so there are no aliasing issues. These macros must

 * also be aware that "fixup_put_user_skip_[12]" are executed in the

 * context of the fault, and any registers used there must be listed

 * as clobbers. In this case only "r1" is used by the current routines.

 * r8/r9 are already listed as err/val.

 */



#ifdef __LP64__
@@ -183,7 +187,8 @@ struct exception_data { 
		"\t.dword\t1b,fixup_put_user_skip_1\n"	    \

		"\t.previous"                               \

		: "=r"(__pu_err)                            \

		: "r"(ptr), "r"(x), "0"(__pu_err))

		: "r"(ptr), "r"(x), "0"(__pu_err)	    \

	    	: "r1")



#define __put_user_asm(stx,x,ptr)                           \

	__asm__ __volatile__ (                              \