288 lines
8.1 KiB
Diff
288 lines
8.1 KiB
Diff
From 57d5e1c07b40e56f6209e7b806208818464f8e8d Mon Sep 17 00:00:00 2001
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From: Nathan Lynch <nathanl@linux.ibm.com>
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Date: Sat, 12 Aug 2023 13:27:39 -0500
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Subject: [PATCH 5/6] librtas/vpd: prefer /dev/papr-vpd when available
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Change rtas_get_vpd() to prefer the /dev/papr-vpd character device
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expected in Linux v6.8.
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On the first invocation of rtas_get_vpd(), probe for the new ABI and
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initialize an internal function pointer according to the result. Use
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pthread_once() to ensure that this probe step is performed atomically
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and only once. It would not make sense to re-probe (and potentially
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update the implementation) on every call, since the implementations
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differ in the way state for the call sequence is maintained.
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Assuming the new ABI is available: upon first call to rtas_get_vpd(),
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open /dev/papr-vpd and obtain a file descriptor using the
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PAPR_VPD_CREATE_HANDLE ioctl() command. This file descriptor is a
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reference to the VPD returned from a complete ibm,get-vpd call
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sequence. Subsequent calls sequentially read the VPD from the fd,
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which is closed once EOF is reached.
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To existing users of rtas_get_vpd(), the new implementation is
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indistinguishable from the old one, with one exception:
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* When using the rtas() syscall on current systems, RTAS advances the
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sequence number by a fixed interval on each call in a sequence. This
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is visible in the values returned in the 'seq_next' out parameter.
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* When using /dev/papr-vpd, the value returned in 'seq_next' does not
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change between calls; librtas treats it as a "handle" for a sequence
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in progress.
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In PAPR there is no meaning attached to the value returned in the
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'seq_next' out parameter, and there is no requirement that it must
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change or increment on each call. No user should be relying on the
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behavior of this aspect of the interface to judge the status of a
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sequence.
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I have verified that an unmodified vpdupdate command from a distro
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lsvpd package works correctly when linked to a librtas.so with this
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change. This is the primary (and perhaps only) user of rtas_get_vpd().
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For now, carry a copy of the kernel uapi header.
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Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
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Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
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---
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Makefile.am | 5 +-
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librtas_src/papr-vpd.h | 22 ++++++
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librtas_src/vpd.c | 155 ++++++++++++++++++++++++++++++++++++-----
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3 files changed, 162 insertions(+), 20 deletions(-)
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create mode 100644 librtas_src/papr-vpd.h
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diff --git a/Makefile.am b/Makefile.am
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index d0cabfb..89a6eaa 100644
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--- a/Makefile.am
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+++ b/Makefile.am
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@@ -26,7 +26,7 @@ LIBRTAS_AGE = 0
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LIBRTAS_LIBRARY_VERSION = $(LIBRTAS_CURRENT):$(LIBRTAS_REVISION):$(LIBRTAS_AGE)
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lib_LTLIBRARIES += librtas.la
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-librtas_la_LDFLAGS = -version-info $(LIBRTAS_LIBRARY_VERSION)
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+librtas_la_LDFLAGS = -version-info $(LIBRTAS_LIBRARY_VERSION) -lpthread
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librtas_la_SOURCES = \
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librtas_src/vpd.c \
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librtas_src/ofdt.c \
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@@ -37,7 +37,8 @@ librtas_la_SOURCES = \
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library_include_HEADERS += librtas_src/librtas.h
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noinst_HEADERS += \
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librtas_src/internal.h \
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- librtas_src/papr-miscdev.h
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+ librtas_src/papr-miscdev.h \
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+ librtas_src/papr-vpd.h
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# See "Updating library version information" in the libtool manual for
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# how to maintain these values. They are *not* tied to the release
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diff --git a/librtas_src/papr-vpd.h b/librtas_src/papr-vpd.h
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new file mode 100644
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index 0000000..b57cf30
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--- /dev/null
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+++ b/librtas_src/papr-vpd.h
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@@ -0,0 +1,22 @@
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+// SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note
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+#ifndef _UAPI_PAPR_VPD_H_
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+#define _UAPI_PAPR_VPD_H_
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+
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+#include <asm/ioctl.h>
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+#include "papr-miscdev.h"
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+
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+struct papr_location_code {
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+ /*
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+ * PAPR+ 12.3.2.4 Converged Location Code Rules - Length
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+ * Restrictions. 79 characters plus nul.
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+ */
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+ char str[80];
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+};
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+
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+/*
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+ * ioctl for /dev/papr-vpd. Returns a VPD handle fd corresponding to
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+ * the location code.
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+ */
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+#define PAPR_VPD_IOC_CREATE_HANDLE _IOW(PAPR_MISCDEV_IOC_ID, 0, struct papr_location_code)
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+
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+#endif /* _UAPI_PAPR_VPD_H_ */
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diff --git a/librtas_src/vpd.c b/librtas_src/vpd.c
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index b2689fb..544560f 100644
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--- a/librtas_src/vpd.c
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+++ b/librtas_src/vpd.c
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@@ -1,33 +1,33 @@
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// SPDX-License-Identifier: LGPL-2.1-or-later
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// Support for accessing IBM Power systems Vital Product Data (VPD)
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-// via the rtas() syscall.
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+// via /dev/papr-vpd or the legacy rtas() syscall.
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-#include <endian.h>
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+#include <errno.h>
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+#include <fcntl.h>
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+#include <inttypes.h>
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+#include <limits.h>
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#include <linux/types.h>
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#include <linux/unistd.h>
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-#include <stdint.h>
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+#include <pthread.h>
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+#include <search.h>
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+#include <stdarg.h>
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+#include <stdbool.h>
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+#include <stdlib.h>
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#include <string.h>
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+#include <sys/ioctl.h>
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+#include <sys/stat.h>
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#include <sys/syscall.h>
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+#include <unistd.h>
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#include "internal.h"
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#include "librtas.h"
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+#include "papr-vpd.h"
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-/**
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- * rtas_get_vpd
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- * @brief Interface to the ibm,get-vpd rtas call
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- *
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- * @param loc_code location code
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- * @param workarea additional args to rtas call
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- * @param size
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- * @param sequence
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- * @param seq_next
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- * @param bytes_ret
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- * @return 0 on success, !0 otherwise
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- */
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-int rtas_get_vpd(char *loc_code, char *workarea, size_t size,
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- unsigned int sequence, unsigned int *seq_next,
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- unsigned int *bytes_ret)
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+static int
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+get_vpd_syscall_fallback(const char *loc_code, char *workarea, size_t size,
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+ unsigned int sequence, unsigned int *seq_next,
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+ unsigned int *bytes_ret)
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{
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uint32_t kernbuf_pa;
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uint32_t loc_pa = 0;
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@@ -79,3 +79,122 @@ int rtas_get_vpd(char *loc_code, char *workarea, size_t size,
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workarea, size, sequence, status, *seq_next, *bytes_ret);
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return rc ? rc : status;
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}
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+
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+static bool get_vpd_can_use_chardev(void)
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+{
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+ struct stat statbuf;
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+
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+ if (stat("/dev/papr-vpd", &statbuf))
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+ return false;
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+
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+ if (!S_ISCHR(statbuf.st_mode))
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+ return false;
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+
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+ if (close(open("/dev/papr-vpd", O_RDONLY)))
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+ return false;
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+
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+ return true;
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+}
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+
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+#define DEVPATH "/dev/papr-vpd"
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+
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+static int vpd_fd_new(const char *loc_code)
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+{
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+ const int devfd = open(DEVPATH, O_WRONLY);
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+ struct papr_location_code lc = {};
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+ int fd = -1;
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+
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+ if (devfd < 0)
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+ return -1;
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+
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+ if (!loc_code)
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+ loc_code = "";
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+
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+ if (sizeof(lc.str) < strlen(loc_code))
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+ goto close_devfd;
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+
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+ strncpy(lc.str, loc_code, sizeof(lc.str));
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+ fd = ioctl(devfd, PAPR_VPD_IOC_CREATE_HANDLE, &lc);
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+close_devfd:
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+ close(devfd);
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+ return fd;
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+}
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+
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+static int
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+get_vpd_chardev(const char *loc_code, char *workarea, size_t size,
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+ unsigned int sequence, unsigned int *seq_next,
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+ unsigned int *bytes_ret)
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+{
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+ int fd = (sequence == 1) ? vpd_fd_new(loc_code) : (int)sequence;
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+
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+ /*
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+ * Ensure we return a fd > 0 in seq_next.
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+ */
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+ if (fd == 1) {
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+ int newfd = dup(fd);
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+ close(fd);
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+ fd = newfd;
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+ }
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+
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+ if (fd < 0)
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+ return -3; /* Synthesize ibm,get-vpd "parameter error" */
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+
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+ int rtas_status = 0;
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+ ssize_t res = read(fd, workarea, size);
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+ if (res < 0) {
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+ rtas_status = -1; /* Synthesize ibm,get-vpd "hardware error" */
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+ close(fd);
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+ } else if (res == 0 || res < (ssize_t)size) {
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+ rtas_status = 0; /* Done with sequence, no more data */
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+ close(fd);
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+ if (seq_next)
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+ *seq_next = 1;
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+ if (bytes_ret)
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+ *bytes_ret = res;
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+ } else {
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+ rtas_status = 1; /* More data available, call again */
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+ if (seq_next)
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+ *seq_next = fd;
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+ if (bytes_ret)
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+ *bytes_ret = res;
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+ }
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+
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+ return rtas_status;
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+}
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+
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+static int (*get_vpd_fn)(const char *loc_code,
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+ char *workarea,
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+ size_t size,
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+ unsigned int sequence,
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+ unsigned int *seq_next,
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+ unsigned int *bytes_ret);
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+
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+static void get_vpd_fn_setup(void)
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+{
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+ get_vpd_fn = get_vpd_can_use_chardev() ?
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+ get_vpd_chardev : get_vpd_syscall_fallback;
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+}
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+
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+/**
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+ * rtas_get_vpd
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+ * @brief Interface to the ibm,get-vpd rtas call
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+ *
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+ * @param loc_code location code
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+ * @param workarea additional args to rtas call
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+ * @param size
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+ * @param sequence
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+ * @param seq_next
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+ * @param bytes_ret
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+ * @return 0 on success, !0 otherwise
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+ */
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+int rtas_get_vpd(char *loc_code, char *workarea, size_t size,
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+ unsigned int sequence, unsigned int *seq_next,
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+ unsigned int *bytes_ret)
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+{
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+ static pthread_once_t get_vpd_fn_once = PTHREAD_ONCE_INIT;
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+
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+ pthread_once(&get_vpd_fn_once, get_vpd_fn_setup);
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+
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+ return get_vpd_fn(loc_code, workarea, size, sequence,
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+ seq_next, bytes_ret);
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+}
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--
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2.43.0
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