linux-kernel - [PATCH] drm/amd/pm: avoid large variable on kernel stack

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Message-Id: <20221215163649.386750-1-arnd@kernel.org>
Date:   Thu, 15 Dec 2022 17:36:31 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Evan Quan <evan.quan@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>
Cc:     Arnd Bergmann <arnd@...db.de>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, Kenneth Feng <kenneth.feng@....com>,
        Hawking Zhang <Hawking.Zhang@....com>,
        Yang Wang <KevinYang.Wang@....com>,
        Chengming Gui <Jack.Gui@....com>,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: [PATCH] drm/amd/pm: avoid large variable on kernel stack

From: Arnd Bergmann <arnd@...db.de>

The activity_monitor_external[] array is too big to fit on the
kernel stack, resulting in this warning with clang:

drivers/gpu/drm/amd/amdgpu/../pm/swsmu/smu13/smu_v13_0_7_ppt.c:1438:12: error: stack frame size (1040) exceeds limit (1024) in 'smu_v13_0_7_get_power_profile_mode' [-Werror,-Wframe-larger-than]

Use dynamic allocation instead. It should also be possible to
have single element here instead of the array, but this seems
easier.

Fixes: 334682ae8151 ("drm/amd/pm: enable workload type change on smu_v13_0_7")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 .../drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c  | 21 ++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c b/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c
index c270f94a1b86..7eba854e09ec 100644
--- a/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c
+++ b/drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_7_ppt.c
@@ -1439,7 +1439,7 @@ static int smu_v13_0_7_get_power_limit(struct smu_context *smu,
 
 static int smu_v13_0_7_get_power_profile_mode(struct smu_context *smu, char *buf)
 {
-	DpmActivityMonitorCoeffIntExternal_t activity_monitor_external[PP_SMC_POWER_PROFILE_COUNT];
+	DpmActivityMonitorCoeffIntExternal_t *activity_monitor_external;
 	uint32_t i, j, size = 0;
 	int16_t workload_type = 0;
 	int result = 0;
@@ -1447,6 +1447,12 @@ static int smu_v13_0_7_get_power_profile_mode(struct smu_context *smu, char *buf
 	if (!buf)
 		return -EINVAL;
 
+	activity_monitor_external = kcalloc(sizeof(activity_monitor_external),
+					    PP_SMC_POWER_PROFILE_COUNT,
+					    GFP_KERNEL);
+	if (!activity_monitor_external)
+		return -ENOMEM;
+
 	size += sysfs_emit_at(buf, size, "                              ");
 	for (i = 0; i <= PP_SMC_POWER_PROFILE_WINDOW3D; i++)
 		size += sysfs_emit_at(buf, size, "%-14s%s", amdgpu_pp_profile_name[i],
@@ -1459,15 +1465,17 @@ static int smu_v13_0_7_get_power_profile_mode(struct smu_context *smu, char *buf
 		workload_type = smu_cmn_to_asic_specific_index(smu,
 							       CMN2ASIC_MAPPING_WORKLOAD,
 							       i);
-		if (workload_type < 0)
-			return -EINVAL;
+		if (workload_type < 0) {
+			result = -EINVAL;
+			goto out;
+		}
 
 		result = smu_cmn_update_table(smu,
 					  SMU_TABLE_ACTIVITY_MONITOR_COEFF, workload_type,
 					  (void *)(&activity_monitor_external[i]), false);
 		if (result) {
 			dev_err(smu->adev->dev, "[%s] Failed to get activity monitor!", __func__);
-			return result;
+			goto out;
 		}
 	}
 
@@ -1495,7 +1503,10 @@ do {													\
 	PRINT_DPM_MONITOR(Fclk_BoosterFreq);
 #undef PRINT_DPM_MONITOR
 
-	return size;
+	result = size;
+out:
+	kfree(activity_monitor_external);
+	return result;
 }
 
 static int smu_v13_0_7_set_power_profile_mode(struct smu_context *smu, long *input, uint32_t size)
-- 
2.35.1