[dpdk-dev] [PATCH 2/2] eal: use base address hint to reserve space for mem config

[Anatoly Burakov <anatoly.burakov@intel.com>]

Currently, mem config will be mapped without using the virtual
area reservation infrastructure, which means it will be mapped
at an arbitrary location. This may cause failures to map the
shared config in secondary process due to things like PCI
whitelist arguments allocating memory in a space where the
primary has allocated the shared mem config.

Fix this by using virtual area reservation to reserve space for
the mem config, thereby avoiding the problem and reserving the
shared config (hopefully) far away from any normal memory
allocations.

Cc: stable@dpdk.org

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 lib/librte_eal/freebsd/eal/eal.c | 27 +++++++++++++++++++++------
 lib/librte_eal/linux/eal/eal.c   | 30 ++++++++++++++++++++++--------
 2 files changed, 43 insertions(+), 14 deletions(-)

diff --git a/lib/librte_eal/freebsd/eal/eal.c b/lib/librte_eal/freebsd/eal/eal.c
index d53f0fe69..fb43c00fd 100644
--- a/lib/librte_eal/freebsd/eal/eal.c
+++ b/lib/librte_eal/freebsd/eal/eal.c
@@ -219,7 +219,8 @@ eal_parse_sysfs_value(const char *filename, unsigned long *val)
 static int
 rte_eal_config_create(void)
 {
-	void *rte_mem_cfg_addr;
+	size_t cfg_len = sizeof(*rte_config.mem_config);
+	void *rte_mem_cfg_addr, *mapped_mem_cfg_addr;
 	int retval;
 
 	const char *pathname = eal_runtime_config_path();
@@ -236,7 +237,7 @@ rte_eal_config_create(void)
 		}
 	}
 
-	retval = ftruncate(mem_cfg_fd, sizeof(*rte_config.mem_config));
+	retval = ftruncate(mem_cfg_fd, cfg_len);
 	if (retval < 0){
 		close(mem_cfg_fd);
 		mem_cfg_fd = -1;
@@ -254,15 +255,29 @@ rte_eal_config_create(void)
 		return -1;
 	}
 
-	rte_mem_cfg_addr = mmap(NULL, sizeof(*rte_config.mem_config),
-				PROT_READ | PROT_WRITE, MAP_SHARED, mem_cfg_fd, 0);
-
-	if (rte_mem_cfg_addr == MAP_FAILED){
+	/* reserve space for config */
+	rte_mem_cfg_addr = eal_get_virtual_area(NULL, &cfg_len,
+			sysconf(_SC_PAGESIZE), EAL_VIRTUAL_AREA_ADDR_IS_HINT,
+			0);
+	if (rte_mem_cfg_addr == NULL) {
 		RTE_LOG(ERR, EAL, "Cannot mmap memory for rte_config\n");
 		close(mem_cfg_fd);
 		mem_cfg_fd = -1;
 		return -1;
 	}
+
+	/* remap the actual file into the space we've just reserved */
+	mapped_mem_cfg_addr = mmap(rte_mem_cfg_addr,
+			cfg_len, PROT_READ | PROT_WRITE,
+			MAP_SHARED | MAP_FIXED, mem_cfg_fd, 0);
+	if (mapped_mem_cfg_addr == MAP_FAILED) {
+		RTE_LOG(ERR, EAL, "Cannot remap memory for rte_config\n");
+		munmap(rte_mem_cfg_addr, cfg_len);
+		close(mem_cfg_fd);
+		mem_cfg_fd = -1;
+		return -1;
+	}
+
 	memcpy(rte_mem_cfg_addr, &early_mem_config, sizeof(early_mem_config));
 	rte_config.mem_config = rte_mem_cfg_addr;
 
diff --git a/lib/librte_eal/linux/eal/eal.c b/lib/librte_eal/linux/eal/eal.c
index 34db78753..ed0ebcc8e 100644
--- a/lib/librte_eal/linux/eal/eal.c
+++ b/lib/librte_eal/linux/eal/eal.c
@@ -305,7 +305,8 @@ eal_parse_sysfs_value(const char *filename, unsigned long *val)
 static int
 rte_eal_config_create(void)
 {
-	void *rte_mem_cfg_addr;
+	size_t cfg_len = sizeof(*rte_config.mem_config);
+	void *rte_mem_cfg_addr, *mapped_mem_cfg_addr;
 	int retval;
 
 	const char *pathname = eal_runtime_config_path();
@@ -330,7 +331,7 @@ rte_eal_config_create(void)
 		}
 	}
 
-	retval = ftruncate(mem_cfg_fd, sizeof(*rte_config.mem_config));
+	retval = ftruncate(mem_cfg_fd, cfg_len);
 	if (retval < 0){
 		close(mem_cfg_fd);
 		mem_cfg_fd = -1;
@@ -348,13 +349,26 @@ rte_eal_config_create(void)
 		return -1;
 	}
 
-	rte_mem_cfg_addr = mmap(rte_mem_cfg_addr, sizeof(*rte_config.mem_config),
-				PROT_READ | PROT_WRITE, MAP_SHARED, mem_cfg_fd, 0);
-
-	if (rte_mem_cfg_addr == MAP_FAILED){
-		close(mem_cfg_fd);
-		mem_cfg_fd = -1;
+	/* reserve space for config */
+	rte_mem_cfg_addr = eal_get_virtual_area(rte_mem_cfg_addr, &cfg_len,
+			sysconf(_SC_PAGESIZE), EAL_VIRTUAL_AREA_ADDR_IS_HINT,
+			0);
+	if (rte_mem_cfg_addr == NULL) {
 		RTE_LOG(ERR, EAL, "Cannot mmap memory for rte_config\n");
+		close(mem_cfg_fd);
+		mem_cfg_fd = -1;
+		return -1;
+	}
+
+	/* remap the actual file into the space we've just reserved */
+	mapped_mem_cfg_addr = mmap(rte_mem_cfg_addr,
+			cfg_len, PROT_READ | PROT_WRITE,
+			MAP_SHARED | MAP_FIXED, mem_cfg_fd, 0);
+	if (mapped_mem_cfg_addr == MAP_FAILED) {
+		munmap(rte_mem_cfg_addr, cfg_len);
+		close(mem_cfg_fd);
+		mem_cfg_fd = -1;
+		RTE_LOG(ERR, EAL, "Cannot remap memory for rte_config\n");
 		return -1;
 	}
 
-- 
2.17.1