Commit 5ce8e39f authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

x86/sgx: Remove .fixup usage 



Create EX_TYPE_FAULT_SGX which does as EX_TYPE_FAULT does, except adds
this extra bit that SGX really fancies having.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20211110101325.961246679@infradead.org
parent fedb24cd

arch/x86/include/asm/extable_fixup_types.h

+2 −0
Original line number Diff line number Diff line
@@ -48,4 +48,6 @@ 
#define	EX_TYPE_ZERO_REG		(EX_TYPE_IMM_REG | EX_DATA_IMM(0))

#define	EX_TYPE_ONE_REG			(EX_TYPE_IMM_REG | EX_DATA_IMM(1))



#define	EX_TYPE_FAULT_SGX		18



#endif

arch/x86/include/asm/sgx.h

+18 −0
Original line number Diff line number Diff line
@@ -45,6 +45,24 @@ enum sgx_encls_function { 
	EMODT	= 0x0F,

};



/**

 * SGX_ENCLS_FAULT_FLAG - flag signifying an ENCLS return code is a trapnr

 *

 * ENCLS has its own (positive value) error codes and also generates

 * ENCLS specific #GP and #PF faults.  And the ENCLS values get munged

 * with system error codes as everything percolates back up the stack.

 * Unfortunately (for us), we need to precisely identify each unique

 * error code, e.g. the action taken if EWB fails varies based on the

 * type of fault and on the exact SGX error code, i.e. we can't simply

 * convert all faults to -EFAULT.

 *

 * To make all three error types coexist, we set bit 30 to identify an

 * ENCLS fault.  Bit 31 (technically bits N:31) is used to differentiate

 * between positive (faults and SGX error codes) and negative (system

 * error codes) values.

 */

#define SGX_ENCLS_FAULT_FLAG 0x40000000



/**

 * enum sgx_return_code - The return code type for ENCLS, ENCLU and ENCLV

 * %SGX_NOT_TRACKED:		Previous ETRACK's shootdown sequence has not

arch/x86/kernel/cpu/sgx/encls.h

+5 −31
Original line number Diff line number Diff line
@@ -11,26 +11,8 @@ 
#include <asm/traps.h>

#include "sgx.h"



/**

 * ENCLS_FAULT_FLAG - flag signifying an ENCLS return code is a trapnr

 *

 * ENCLS has its own (positive value) error codes and also generates

 * ENCLS specific #GP and #PF faults.  And the ENCLS values get munged

 * with system error codes as everything percolates back up the stack.

 * Unfortunately (for us), we need to precisely identify each unique

 * error code, e.g. the action taken if EWB fails varies based on the

 * type of fault and on the exact SGX error code, i.e. we can't simply

 * convert all faults to -EFAULT.

 *

 * To make all three error types coexist, we set bit 30 to identify an

 * ENCLS fault.  Bit 31 (technically bits N:31) is used to differentiate

 * between positive (faults and SGX error codes) and negative (system

 * error codes) values.

 */

#define ENCLS_FAULT_FLAG 0x40000000



/* Retrieve the encoded trapnr from the specified return code. */

#define ENCLS_TRAPNR(r) ((r) & ~ENCLS_FAULT_FLAG)

#define ENCLS_TRAPNR(r) ((r) & ~SGX_ENCLS_FAULT_FLAG)



/* Issue a WARN() about an ENCLS function. */

#define ENCLS_WARN(r, name) {						  \
@@ -50,7 +32,7 @@ 
 */

static inline bool encls_faulted(int ret)

{

	return ret & ENCLS_FAULT_FLAG;

	return ret & SGX_ENCLS_FAULT_FLAG;

}



/**
@@ -88,11 +70,7 @@ static inline bool encls_failed(int ret) 
	asm volatile(						\

	"1: .byte 0x0f, 0x01, 0xcf;\n\t"			\

	"2:\n"							\

	".section .fixup,\"ax\"\n"				\

	"3: orl $"__stringify(ENCLS_FAULT_FLAG)",%%eax\n"	\

	"   jmp 2b\n"						\

	".previous\n"						\

	_ASM_EXTABLE_FAULT(1b, 3b)				\

	_ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_FAULT_SGX)		\

	: "=a"(ret)						\

	: "a"(rax), inputs					\

	: "memory", "cc");					\
@@ -127,7 +105,7 @@ static inline bool encls_failed(int ret) 
 *

 * Return:

 *   0 on success,

 *   trapnr with ENCLS_FAULT_FLAG set on fault

 *   trapnr with SGX_ENCLS_FAULT_FLAG set on fault

 */

#define __encls_N(rax, rbx_out, inputs...)			\

	({							\
@@ -136,11 +114,7 @@ static inline bool encls_failed(int ret) 
	"1: .byte 0x0f, 0x01, 0xcf;\n\t"			\

	"   xor %%eax,%%eax;\n"					\

	"2:\n"							\

	".section .fixup,\"ax\"\n"				\

	"3: orl $"__stringify(ENCLS_FAULT_FLAG)",%%eax\n"	\

	"   jmp 2b\n"						\

	".previous\n"						\

	_ASM_EXTABLE_FAULT(1b, 3b)				\

	_ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_FAULT_SGX)		\

	: "=a"(ret), "=b"(rbx_out)				\

	: "a"(rax), inputs					\

	: "memory");						\

arch/x86/mm/extable.c

+10 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <asm/traps.h>

#include <asm/kdebug.h>

#include <asm/insn-eval.h>

#include <asm/sgx.h>



static inline unsigned long *pt_regs_nr(struct pt_regs *regs, int nr)

{
@@ -47,6 +48,13 @@ static bool ex_handler_fault(const struct exception_table_entry *fixup, 
	return ex_handler_default(fixup, regs);

}



static bool ex_handler_sgx(const struct exception_table_entry *fixup,

			   struct pt_regs *regs, int trapnr)

{

	regs->ax = trapnr | SGX_ENCLS_FAULT_FLAG;

	return ex_handler_default(fixup, regs);

}



/*

 * Handler for when we fail to restore a task's FPU state.  We should never get

 * here because the FPU state of a task using the FPU (task->thread.fpu.state)
@@ -207,6 +215,8 @@ int fixup_exception(struct pt_regs *regs, int trapnr, unsigned long error_code, 
		return ex_handler_pop_zero(e, regs);

	case EX_TYPE_IMM_REG:

		return ex_handler_imm_reg(e, regs, reg, imm);

	case EX_TYPE_FAULT_SGX:

		return ex_handler_sgx(e, regs, trapnr);

	}

	BUG();

}