Commit d72500f9 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/64s/syscall: Fix ptrace syscall info with scv syscalls 



The scv implementation missed updating syscall return value and error
value get/set functions to deal with the changed register ABI. This
broke ptrace PTRACE_GET_SYSCALL_INFO as well as some kernel auditing
and tracing functions.

Fix. tools/testing/selftests/ptrace/get_syscall_info now passes when
scv is used.

Fixes: 7fa95f9a ("powerpc/64s: system call support for scv/rfscv instructions")
Cc: stable@vger.kernel.org # v5.9+
Reported-by: default avatar"Dmitry V. Levin" <ldv@altlinux.org>
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Reviewed-by: default avatarDmitry V. Levin <ldv@altlinux.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210520111931.2597127-2-npiggin@gmail.com
parent 5665bc35

arch/powerpc/include/asm/ptrace.h

+26 −19
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#ifndef _ASM_POWERPC_PTRACE_H

#define _ASM_POWERPC_PTRACE_H



#include <linux/err.h>

#include <uapi/asm/ptrace.h>

#include <asm/asm-const.h>
@@ -152,25 +153,6 @@ extern unsigned long profile_pc(struct pt_regs *regs); 
long do_syscall_trace_enter(struct pt_regs *regs);

void do_syscall_trace_leave(struct pt_regs *regs);



#define kernel_stack_pointer(regs) ((regs)->gpr[1])

static inline int is_syscall_success(struct pt_regs *regs)

{

	return !(regs->ccr & 0x10000000);

}



static inline long regs_return_value(struct pt_regs *regs)

{

	if (is_syscall_success(regs))

		return regs->gpr[3];

	else

		return -regs->gpr[3];

}



static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)

{

	regs->gpr[3] = rc;

}



#ifdef __powerpc64__

#define user_mode(regs) ((((regs)->msr) >> MSR_PR_LG) & 0x1)

#else
@@ -235,6 +217,31 @@ static __always_inline void set_trap_norestart(struct pt_regs *regs) 
	regs->trap |= 0x1;

}



#define kernel_stack_pointer(regs) ((regs)->gpr[1])

static inline int is_syscall_success(struct pt_regs *regs)

{

	if (trap_is_scv(regs))

		return !IS_ERR_VALUE((unsigned long)regs->gpr[3]);

	else

		return !(regs->ccr & 0x10000000);

}



static inline long regs_return_value(struct pt_regs *regs)

{

	if (trap_is_scv(regs))

		return regs->gpr[3];



	if (is_syscall_success(regs))

		return regs->gpr[3];

	else

		return -regs->gpr[3];

}



static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)

{

	regs->gpr[3] = rc;

}



#define arch_has_single_step()	(1)

#define arch_has_block_step()	(true)

#define ARCH_HAS_USER_SINGLE_STEP_REPORT

arch/powerpc/include/asm/syscall.h

+26 −16
Original line number Diff line number Diff line
@@ -41,12 +41,18 @@ static inline void syscall_rollback(struct task_struct *task, 
static inline long syscall_get_error(struct task_struct *task,

				     struct pt_regs *regs)

{

	if (trap_is_scv(regs)) {

		unsigned long error = regs->gpr[3];



		return IS_ERR_VALUE(error) ? error : 0;

	} else {

		/*

		 * If the system call failed,

		 * regs->gpr[3] contains a positive ERRORCODE.

		 */

		return (regs->ccr & 0x10000000UL) ? -regs->gpr[3] : 0;

	}

}



static inline long syscall_get_return_value(struct task_struct *task,

					    struct pt_regs *regs)
@@ -58,11 +64,14 @@ static inline void syscall_set_return_value(struct task_struct *task, 
					    struct pt_regs *regs,

					    int error, long val)

{

	if (trap_is_scv(regs)) {

		regs->gpr[3] = (long) error ?: val;

	} else {

		/*

	 * In the general case it's not obvious that we must deal with CCR

	 * here, as the syscall exit path will also do that for us. However

	 * there are some places, eg. the signal code, which check ccr to

	 * decide if the value in r3 is actually an error.

		 * In the general case it's not obvious that we must deal with

		 * CCR here, as the syscall exit path will also do that for us.

		 * However there are some places, eg. the signal code, which

		 * check ccr to decide if the value in r3 is actually an error.

		 */

		if (error) {

			regs->ccr |= 0x10000000L;
@@ -72,6 +81,7 @@ static inline void syscall_set_return_value(struct task_struct *task, 
			regs->gpr[3] = val;

		}

	}

}



static inline void syscall_get_arguments(struct task_struct *task,

					 struct pt_regs *regs,