driver: respect stack frame limit

svec_fpga_app_init() declares too many local buffers that are allocated on the stack. On some versions of GCC this is detected and reported, causing a warning that is promoted to an error. Example: svec-core-fpga.c:710:1: error: the frame size of 1968 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] Since apparently it is not a very good idea to increase the stack frame size limit [1], the solution implemented here is to switch to dynimically allocating the biggest buffer (struct resource res[]). [1]: https://gcc.gnu.org/onlinedocs/gccint/Stack-Checking.html#Stack-Checking "The maximum size of a stack frame, in bytes. GCC will generate probe instructions in non-leaf functions to ensure at least this many bytes of stack are available. If a stack frame is larger than this size, stack checking will not be reliable and GCC will issue a warning. The default is chosen so that GCC only generates one instruction on most systems. You should normally not change the default value of this macro." Signed-off-by: Dimitris Lampridis <dimitris.lampridis@cern.ch>

driver: respect stack frame limit
svec_fpga_app_init() declares too many local buffers that are allocated on the stack. On some versions of GCC this is detected and reported, causing a warning that is promoted to an error. Example: svec-core-fpga.c:710:1: error: the frame size of 1968 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] Since apparently it is not a very good idea to increase the stack frame size limit [1], the solution implemented here is to switch to dynimically allocating the biggest buffer (struct resource res[]). [1]: https://gcc.gnu.org/onlinedocs/gccint/Stack-Checking.html#Stack-Checking "The maximum size of a stack frame, in bytes. GCC will generate probe instructions in non-leaf functions to ensure at least this many bytes of stack are available. If a stack frame is larger than this size, stack checking will not be reliable and GCC will issue a warning. The default is chosen so that GCC only generates one instruction on most systems. You should normally not change the default value of this macro." Signed-off-by: Dimitris Lampridis <dimitris.lampridis@cern.ch>
181ad487 · Dimitris Lampridis · 9ec20cf1 · 181ad487
Commit 181ad487 authored Mar 03, 2020 by Dimitris Lampridis
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Showing with 19 additions and 12 deletions

svec-core-fpga.c software/kernel/svec-core-fpga.c +19 -12

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--- a/software/kernel/svec-core-fpga.c
+++ b/software/kernel/svec-core-fpga.c
@@ -648,22 +648,26 @@ static int svec_fpga_app_init(struct svec_fpga *svec_fpga)
 #define SVEC_FPGA_APP_RES_N (32 - SVEC_FPGA_APP_IRQ_BASE + 1)
 	struct vme_dev *vdev = to_vme_dev(svec_fpga->dev.parent);
 	unsigned int res_n = SVEC_FPGA_APP_RES_N;
-	struct resource res[SVEC_FPGA_APP_RES_N] = {
-		[0] = {
-			.name = "app-mem",
-			.flags = IORESOURCE_MEM,
-		},
-	};
+	struct resource *res;
 	struct platform_device *pdev;
 	struct irq_domain *vic_domain;
 	char app_name[SVEC_FPGA_APP_NAME_MAX];
 	unsigned long app_offset;
-	int err, fn = svec_fpga->function_nr;
+	int err = 0, fn = svec_fpga->function_nr;
+
+	res = kzalloc(SVEC_FPGA_APP_RES_N * sizeof(struct resource), GFP_KERNEL);
+	if (!res) {
+		return -ENOMEM;
+	}
+
+	res[0].name  = "app-mem";
+	res[0].flags = IORESOURCE_MEM;

 	app_offset = svec_fpga_csr_app_offset(svec_fpga);
 	if (!app_offset) {
 		dev_warn(&svec_fpga->dev, "Application not found\n");
-		return 0;
+		err = 0;
+		goto err_free;
 	}

 	svec_fpga_metadata_get(&svec_fpga->meta_app,
@@ -695,18 +699,21 @@ static int svec_fpga_app_init(struct svec_fpga *svec_fpga)
 	err = svec_fpga_app_id_build(svec_fpga, app_offset,
 				     app_name, SVEC_FPGA_APP_NAME_MAX);
 	if (err)
-		return err;
+		goto err_free;
 	svec_fpga_app_restart(svec_fpga);
 	pdev = platform_device_register_resndata(&svec_fpga->dev,
 						 app_name, PLATFORM_DEVID_AUTO,
 						 res, res_n,
 						 NULL, 0);
-	if (IS_ERR(pdev))
-		return PTR_ERR(pdev);
+	err = IS_ERR(pdev);
+	if (err)
+		goto err_free;

 	svec_fpga->app_pdev = pdev;

-	return 0;
+err_free:
+	kfree(res);
+	return err;
 }

 static void svec_fpga_app_exit(struct svec_fpga *svec_fpga)